Parkinson's Disease Glossary

Acetylcholine:

One of the chemical neurotransmitters in the brain and other areas of the central and peripheral nervous system. It is found in the basal ganglia, where it influences movement located in different regions of the brain as well, and plays a role in walking, memory, and vision. Drugs that block acetylcholine receptors (socalled anticholinergics) are occasionally utilized in the treatment of PD while drugs that enhance its activity (acetylcholinesterase inhibitors) can be used to treat some of the gait and hallucinatory problems seen in PD.

Acetylcholinesterase Inhibitors:

A drug that inhibits the enzyme that breaks down acetylcholine resulting in increased activity of the chemical neurotransmitter acetylcholine. Used to treat mild to moderate dementia in Parkinson's disease as well as some of the gait problems

Agonist:

A chemical or drug that can activate a neurotransmitter receptor. Dopamine agonists, such as pramipexole, ropinirole, rotigotine, and apomorphine, are used in the treatment of PD.

Aggregate:

A whole formed by the combination of several elements. In Parkinson's disease, there is a clumping of many proteins inside neurons, including alpha-synuclein. Lewy bodies are a kind of aggregate found in PD.

Akinesia:

Literally, means loss of movement also described as a difficulty with initiating voluntary movements. It is commonly used interchangeably with bradykinesia; however, bradykinesia means slow movement.

Alpha-synuclein:

A protein present in nerve cells (as well as other cells in the body). The accumulation and aggregation of this protein is a pathologic finding in PD. The first genetic mutation found in PD was discovered in the gene for alpha-synuclein (SNCA) and was called PARK1. Alpha-synuclein also accumulates in multiple system atrophy (MSA) and Lewy Body Disease (LBD). Alpha-synuclein seems to play a key role in the pathogenesis of PD and is important for some nerve functions such as releasing neurotransmitters.

Alexander Technique: 

This technique is a form of complementary therapy, pioneered at the turn of the century by FM Alexander. The principal aim is to help improve health by teaching people to stand and move more efficiently.

Amantadine:

A medication used to treat Parkinson's disease as a single therapy or with L-DOPA and other medications. It has both an anti-Parkinson effect and an anti-dyskinesia effect.

Amygdala: 

An almond-shaped nucleus located deep in the brain's medial temporal lobe in animals. It is involved in fear and anxiety responses, and the formation of memories involving emotion.

Anhedonia:

Decreased ability or inability to experience pleasure.

Anosmia:

Total loss of the sense of smell. See also Hyposmia

Antagonists: 

Has the opposite effect from an agonist. Antagonists block neurotransmitter receptors. Dopamine antagonists can worsen Parkinson's symptoms and can cause drug-induced Parkinsonism. Virtually all antipsychotic drugs have dopamine antagonist action as do some anti-sickness medications.

Anticholinergics: 

A type of medication that interferes with the action of acetylcholine. It is sometimes used in younger patients with PD who have a lot of tremors. They are not recommended for use in the elderly because they can cause confusion. One example is trihexyphenidyl hydrochloride.

Antisense oligonucleotides (ASOs): 

A new treatment designed to stop the RNA that converts a bit of DNA (gene) into the protein. For example, an ASO against alpha-synuclein would target the alpha-synuclein RNA and stop it from being made into a protein thus reducing the levels of alpha-synuclein.

Apathy:

Lack of interest, enthusiasm, or concern

Apomorphine: 

A type of dopamine agonist, which is highly powerful and effective but also causes unpleasant effects, such as nausea. A pump delivering apomorphine can be used in more advanced stages of the disease or it can also be used intermittently where it is given as rescue injections in patients who suddenly go "off."

Astrocytes:

They are major non-neuronal support cells in the brain. Among other things, they secrete growth factors that help neurons grow and communicate. They can also pump glutamate, a neurotransmitter that, in excess, can cause neurotoxicity.

Ataxia:

Inability to coordinate voluntary muscle movements; unsteady movements and staggering gait.

ATP13A2 (PARK 9):

A gene that codes for a form of the ATPase enzyme. When mutated, this gene may cause a form of early-onset Parkinson's.

Autonomic Nervous System (ANS):

Part of the peripheral nervous system, consisting of sympathetic and parasympathetic nerves that control involuntary actions, in particular the heartbeat, blood pressure, and the bladder and gut as well as some sexual functions.

Autonomic Dysfunction:

Any abnormal functioning of the autonomic nervous system resulting in problems with bodily functions such as bowel and bladder control, blood pressure control, sweating, drooling, and so forth. Examples of autonomic dysfunction issues are constipation, urinary incontinence, and orthostatic hypotension (low blood pressure when standing).

Autophagy: 

The segregation and disposal of damaged organelles within a cell. This is a normal physiological process in the body. It maintains normal functioning by protein degradation and turnover of the destroyed cell organelles for new cell formation. During cellular stress, the process of autophagy is increased. Cellular stress is caused when there is a deprivation of nutrients and/or growth factors. Autophagy may provide an alternate source of intracellular building blocks and substrates that may generate energy to enable continuous cell survival. Dysfunctional autophagy can lead to the building of damaged organelles and misfolded proteins in the cell.

Autosomes/autosomal: 

Refers to all the chromosomes excluding the sex-related X and Y chromosomes.

Axon:

The part of the nerve that carries electrical impulses from the nerve cell body to other neurons both throughout the limbs (peripheral nervous system) and brain/spinal cord (central nervous system). Thick axons tend to be through the brain and spinal cord; they are surrounded by a protective fatty sheath called myelin (in multiple sclerosis the myelin is damaged). Thin axons tend to be unmyelinated. In PD, alpha-synuclein is deposited in long, thin axons, and these are called Lewy neurites.

Basal Ganglia: 

A collection of structures deep within the brain that consist of the caudate nucleus, putamen, globus pallidus, subthalamic nucleus, and substantia nigra that play an important role in movement and some forms of thinking. Dopamine cell death in the substantia nigra contributes to Parkinsonian signs.

Big data:

A term for data sets that are so large or complex that traditional data processing applications are inadequate.

Biomarker: 

A marker, typically in bodily fluids (e.g. blood, CSF), that can be used to either diagnose or track disease and/or help divide patients up into different subgroups. Of late there has been much interest in finding biomarkers that could indicate that the person has a disease before symptoms of that disease appear.

Autosomal recessive:

A mode of inheritance of genetic traits located on the autosomes that only manifests when two copies of a mutated gene (two alleles) are present. For a particular trait to be expressed, both parents must have the particular mutated allele or gene, and both must pass it to the offspring who then manifests the genetic disease. Some genetic forms of PD are autosomal recessive, such as from the genes known as PARKIN, PINK1, and DJ1. In some cases, the gene of interest is missing. In others, there are abnormalities and if two different abnormalities of the same gene are inherited, that can result in recessive inheritance.

Blood-brain barrier: 

The selectively permeable structure that separates the circulating blood from the brain; it forms a tight physical barrier that normally keeps immune cells, and some chemicals and drugs out of the brain. Formed of astrocyte end feet, endothelial cells of the blood vessels, and pericytes.

Braak Staging:

A method to classify the degree of pathology in Parkinson's disease on brain autopsy, based on the idea that more brain regions contain alpha-synuclein pathology as Parkinson's disease progresses over time. There is also a (different) Braak staging for Alzheimer's disease.

Bradykinesia:

Literally, means slowness of movement. It is commonly (but erroneously) used synonymously with akinesia and hypokinesia. Bradykinesia is a clinical hallmark of Parkinsonism.

Bradyphrenia:

Slowness of thought common to many brain disorders.

Brain stem: 

The lower part of the brain that lies between the two cerebral hemispheres and the top of the spinal cord. The three parts of the brain stem are the medulla oblongata, pons, and midbrain. The brain stem is a vital structure that is a passageway between the brain and spinal cord, and it contains neurons involved in sleep and wakefulness, as well as the main centers that command vital functions such as respiration and heart function. The substantia nigra, which is damaged in Parkinson's, is located at the top of the brainstem, in the midbrain.

C-Abl:

A gene implicated in the processes of cell differentiation, cell division, cell adhesion, and stress response.

Calcium:

An essential mineral. Calcium is important for normal neurotransmission between nerve cells and is involved in many chemical reactions within neurons and in mitochondrial function. Calcium overload in the substantia nigra has been postulated as one mechanism that could contribute to the death of these neurons.

Carbidopa:

A drug given with levodopa. Carbidopa blocks the enzyme dopa decarboxylase, thereby preventing levodopa from being metabolized to dopamine in the body. Because carbidopa does not penetrate the blood-brain barrier, it only blocks levodopa metabolism in the peripheral tissues and not in the brain, thereby reducing side effects, but increasing the effectiveness of levodopa in the brain.

Carer/Care Partner:

A name used to describe anyone who provides help or support of any kind to a relative or friend.

Caudate nucleus:

A nucleus located in the basal ganglia important in learning and memory. It is one component of the basal ganglia called the striatum. The other component is the putamen.

Cell therapy: 

The use of cells transplanted into an individual as a treatment for disease. These cells can be derived from the same person's body, taken from another individual, or grown from stem cells in the laboratory. For Parkinson's disease, clinical trials are looking at whether dopamine cells can be transplanted into the brain to replace those lost as part of the disease.

Central Nervous System (CNS): 

Consists of the brain, brain stem, and spinal cord.

Duodopa:

An advanced Parkinson's therapy. It is a new means of delivering a particular form of L-dopa via a pump directly in the small intestines.

Dysarthria: 

Impaired speech articulation. It is very common in Parkinson's and needs to be distinguished from dysphasia, which is a problem in understanding and producing speech.

Dysbiosis: 

A imbalance between the types of organisms present in a person's natural microflora, especially that of the gut, thought to contribute to a range of conditions of ill health.

Dyskinesia: 

Abnormal involuntary movements; also, sometimes called hyperkinesia and typically caused in advancing Parkinson's by L-dopa drugs.

Dysphagia: 

Difficulty in swallowing

Dystonia: 

Characterized by persistent or intermittent contractions of opposing muscles causing abnormal movements or postures. It should not be confused with dyskinesia. It is most seen first thing in the morning in Parkinson's in the foot when the patient is OFF. It can be seen occasionally as a result of L-dopa medication.

Embryonic stem (ES) cells: 

See stem cells

Encephalitis: 

nflammation of the brain. See neuroinflammation.

Entacapone: 

A Parkinson's drug that is used alongside levodopa and carbidopa. It inhibits the enzyme COMT, decreasing the breakdown of levodopa.

Exosomes:

A subtype of extracellular vesicles (EVs), which are small ball-like structures produced by all living cells (human and bacterial) and can be found in all sorts of body fluids such as blood urine, and CSF and cultured medium of cell cultures. They are formed inside the cell and are released outside the cell carrying lipids, proteins, or other contents. Their vehicle-like properties have the potential to deliver therapeutic or detrimental cellular cargo.

Executive Dysfunction: 

A deficit in executive functioning that may occur in Parkinson's disease and may have a dopaminergic basis. Executive functioning allows the completion of tasks using higherlevel mental skills such as planning, organization, memory, flexible thinking, and self-regulation.

Festination: 

An involuntary quickening of the gait; the acceleration of gait noted in Parkinsonism and similar disorders, means "chasing the center of gravity.

Foscarbidopa/Foslevodopa: 

Prodrugs of carbidopa/levodopa that are used in a subcutaneous infusion pump (like an insulin pump) in some parts of the world. It is not yet approved worldwide.

Freezing of Gait (FOG):

The sudden brief inability to walk or to continue walking which typically occurs in narrow spaces

Functional magnetic resonance imaging (fMRi):

An imaging technique designed specifically for the brain. It measures the rate at which oxygen is removed from the blood to the cells, therefore suggesting the activity of a particular area of the brain.

GABA (gamma amino butyric acid): 

The principal inhibitory neurotransmitter in the human brain. GABA neurons are rich in the striatum, globus pallidus, substantia nigra, and cerebellum.

GBA (Glucocerebrosidase):

An enzyme found within the lysosome of cells. Mutations in the GBA gene are associated with Parkinson's disease.

Gastroparesis:

Also called delayed gastric emptying, is a condition in which the stomach takes too long to empty its contents, and can affect people with PD.

GDNF:

Glial cell line Derived Neurotrophic Factor. See growth factors.

Gene therapy:

The insertion of genes into an individual's cells and tissues to replace or bolster a particular function within those cells The genes are usually placed within a non-pathogenic virus, which serves as the vector to penetrate the cells. Gene therapy can also be used to correct non-genetic deficiencies such as the loss of dopamine in Parkinson's, to modify the function of a group of cells (e.g. convert an excitatory structure to one that is inhibitory), or to provide a source of growth factors.

Genotype:

The collection of genetic material in an organism that gives rise to its characteristics.

Glia (Glia cells):

Non-neural calls of the brain, commonly called neuroglia or simply glia (Greek for "glue"), that maintain homeostasis, form myelin, and provide support and protection for the brain's neurons. Astrocytes, microglia, and oligodendrocytes are three main glial cells.

Globus pallidus:

A major part of the basal ganglia involved in movement control. It is split into two main parts: the internal globus pallidus (GPi), and the external globus pallidus (GPe). Deep brain stimulation of the GPi causes an increase in motor function in Parkinson's patients. Often patients also show a reduction in dyskinesia, probably because they require less levodopa.

Glucose:

A simple sugar that is an important energy source in living organisms and is a component of many carbohydrates. Impaired glucose metabolism has recently been associated with PD and may underline the association between type-2 diabetes and Parkinson's disease.

Glutamate: 

An amino acid and the main excitatory neurotransmitter in the human brain. The major input to the striatum is from the cerebral cortex which uses glutamate as a neurotransmitter. In PD. the loss of dopaminergic neurons can lead to high concentrations of glutamate in the basal ganglia and can cause neuronal damage.

Glycation: 

The bonding of a carbohydrate (sugar molecule or 'glycan') to a protein or lipid molecule without enzymatic regulation. See glycosylation. Abnormal glycation can occur in PD and may underline oxidative stress and inflammation.

Glycosylation:

The bonding of a carbohydrate to a protein or lipid molecule with enzymatic regulation. See glycation. Abnormal glycosylation can occur in PD and may underline oxidative stress and inflammation.

Glycosylceramide:

A type of cerebroside. Cerebrosides are a critical component in muscle and nerve cell membranes.

Growth factors: 

Naturally occurring substances (usually proteins) that help maintain the health of neurons and encourage cell growth, proliferation, and differentiation. Some growth factors are being looked at to try to promote the survival of the neural cells that are degenerating in Parkinson's of which the one that has been trialed the most is GDNF.

Gut microbiome: 

Genetic material or genes harbored by the community of microorganisms that live in the gut. See gut microbiota.

Gut microbiota: 

The complex community of microorganisms (bacteria, archaea, fungi, yeasts) that live in the digestive tracts of humans and other animals. These microorganisms can be beneficial, for example, aiding in digestion and absorption of nutrients, or harmful to health.

Heterogeneity: 

Lacking uniformity in composition or character, applied to a group under a category that seems to be diverse in other qualities. (as opposed to homogeneity, which is uniformity in composition or character). This term is most often used to describe the different types of Parkinson's disease.

Hippocampus: 

A complex neural structure (shaped like a sea horse) located in the temporal lobes of the brain; involved in memory storage, motivation, and emotion as part of the limbic system.

Hoehn and Yahr scale: 

A commonly used system for describing how the symptoms of Parkinson's disease progress. The higher the stage, the more advanced the disease.?

Stage 0: No signs of disease.

Stage 1: Unilateral symptoms only.

Stage 1.5: Unilateral and axial (midline) involvement.

Stage 2:Bilateral symptoms. No impairment of balance.

Stage 2.5: Mild bilateral disease with recovery on pull test.

Stage 3: Balance impairment. Mild to moderate disease. Physically independent.

Stage 4: Severe disability, but still able to walk or stand unassisted

Stage 5: Needing a wheelchair or bedridden unless assisted.

Hyperkinesia:

An abnormal increase in movement and/or muscle activity; sometimes used synonymously with dyskinesia.

Hypokinesia:

Means reduced amplitude of movement. It is commonly used synonymously (but erroneously) with akinesia and bradykinesia.

Hypothalamic pituitary adrenal axis (HPA):

The three primary components of the endocrine system. Made up of the hypothalamus, pituitary gland, and the adrenal cortex, the HPA has a wide range of functions from stimulating the stress response to controlling digestion, the immune system, mood, sexuality, and energy storage and consumption.

Hypothalamus:

A brain region that links the limbic system to the pituitary gland and is a master area for the autonomic nervous system as well as being important in appetite and sleep.

Idiopathic: 

Arising from an unknown cause.

Idiopathic Parkinson's disease: 

 This term is used to describe the common type of Parkinson's disease to distinguish it from other forms of Parkinsonism (also termed "Sporadic PD").

Impulse control disorder (ICD):

A set of psychiatric disorders characterized by an inability to control one's actions, particularly those that might bring harm to oneself or others. Common ICDs in patients receiving dopamine agonists are pathologic gambling, compulsive eating, compulsive shopping, and hypersexuality.

Inflammation: 

Acute inflammation is a normal part of the body's response to injury or infection. Inflammation occurs when the body releases chemicals that trigger an immune response to fight off infection or heal damaged tissue. Once the injury or infection is healed, the inflammatory process ends. Chronic inflammation is slow, long-term inflammation lasting for prolonged periods of several months to years. The extent and effects of chronic inflammation vary with the injury's cause and the body's ability to repair and overcome the damage.

Interdisciplinary care:

Multiple healthcare professionals collaborate to provide care with a common perspective, often involving joint consultations.

Induced pluripotent stem cells (iPS Cells):

Stem cells that can be generated directly from adult cells such as blood or skin cells. See stem cells.

Learned voluntary movements: 

Movements that we learn to do, like walking and talking.

Leucine-rich repeat kinase 2 (LRRK2):

A protein encoded by the LRRK2 gene which when mutated can lead to Parkinson's. Several different mutations in the LRRK2 gene have been found to cause Parkinson's disease, but there may also be variants within the general population that do not necessarily cause disease. LRRK2 is highly expressed in immune cells in the body.

Levodopa (L-DOPA):

A chemical that is the precursor to dopamine. It can pass through the blood-brain barrier (whereas dopamine cannot). Once it has entered the central nervous system, L-dopa is converted into dopamine by aromatic L-amino acid decarboxylase (DOPA decarboxylase/DDC). L-DOPA is also converted into dopamine within the peripheral nervous system, but this is usually blocked by employing peripherally active dopa decarboxylase inhibitors to avoid unwanted effects.

Lewy bodies:

A pathologic hallmark of Parkinson's disease and dementia with Lewy bodies. First described by Frederic Lewy in 1912, Lewy bodies are seen microscopically as inclusions in neurons in several brain regions, including the substantia nigra and locus coeruleus. One protein seen is alpha-synuclein in an aggregated form. Aggregates of this protein in axons are called Lewy neurites.

Lysosome:

Cell organelle containing different enzymes that can break down molecules like proteins, nucleic acids, carbohydrates, and lipids.

Magnetic resonance imaging (MRI):

A noninvasive medical imaging technique to visualize detailed internal structure and limited function of the body. MRI provides a much greater contrast between the different soft tissues of the body than computed tomography (CT), making it especially useful in neurological (brain) imaging.

MAO (monoamine oxidase):

A family of enzymes with two subtypes: MAO-A and MAO-B. These catalyze the oxidation of amine molecules (replacing the amine group with an oxygen molecule.)

-MAO-A inhibitors: Drugs that inhibit the MAO-A enzyme, which is responsible for the metabolism of dietary tyramine. MAO-A inhibitors can cause tyramine-induced hypertension, the socalled "cheese effect" because tyramine can be found in high concentrations in some soft cultured cheeses.

-MAO-B inhibitors: These drugs (e.g. selegiline, rasagiline, safinamide) inhibit the breakdown of dopamine via MAO-B enzyme and do not cause the "cheese effect" of hypertension.

MPTP (N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine):

A neurotoxin precursor of MPP+ that is taken up in dopamine nerve terminals. MPP+ damages the dopamine cells. MPTP is catalyzed to MPP+ by MAO-B. MPTP has been widely used to create an animal model of Parkinsonism by depleting substantia nigra dopamine neurons. It was discovered by accident in the early 1980s when it was accidentally manufactured in an illicit drug and led to a new form of young onset parkinsonism, with the group of affected individuals often being called the "frozen addicts".

Microbiome: 

The microorganisms (bacteria, viruses, fungi) and their collection of genes that populate a particular environment such as a barrier site where one's body is in touch with the external environment, including gut, lung, skin, etc. See gut microbiome.

Microglia: 

A type of glial cell that shares many properties with macrophages; it provides the first immune defense mechanism in the brain and central nervous system.

Micrographia: 

Cramped, small handwriting that approximately 50% of people with Parkinson's exhibit.

Mild Cognitive Impairment (MCI):

A decline in memory or intellectual functioning that is not as severe as that found in dementia

Mitochondria: 

Aspherical or elongated organelle in the cytoplasm of nearly all cells, containing genetic material and many enzymes important for cell metabolism, including those responsible for the conversion of food to usable energy. Mitochondrial dysfunction has been strongly implicated in Parkinson's disease.

Mitophagy:

The selective degradation of mitochondria by autophagy. See Mitochondria and Autophagy.

Motor skills: 

The degree of control or coordination provided by brain control of the skeletal muscles.

Motor symptoms: 

Symptoms that involve movement, coordination, physical tasks, or mobility. These include, among others: resting tremor, bradykinesia, rigidity, postural instability, freezing, micrographia, mask-like expression, unwanted accelerations, stooped posture, dystonia, impaired motor dexterity and coordination, speech problems, difficulty swallowing, muscle cramping, and drooling of saliva. See non-motor symptoms.

Movement Disorder Specialist (MDS): 

A neurologist who has a special interest in and extra training and experience with movement disorders such as Parkinson's disease.

MRI-focused ultrasound therapy:

A therapy that allows one to lesion-selective areas of the brain by focusing ultrasound on specific sites using MRI guidance. It is used in some patients instead of DBS.

Multidisciplinary care:

Care given by multiple healthcare professionals each approaching the patient from their professional perspective, often involves separate, individual consultations.

Multiple System Atrophy (MSA): 

A less common degenerative neurological disorder that causes symptoms similar to Parkinson's disease but with more widespread damage to the central nervous system. Other systems involved besides the basal ganglia include the cerebellum and autonomic systems. MSA is sometimes called a Parkinson-plus syndrome or Atypical Parkinson's. It typically does not respond well to the drugs used to treat Parkinson's.

Neuroinflammation: 

Inflammatory state of the brain or spinal cord. It could be initiated in response to several stimuli including aging, infection, traumatic brain injury, toxic metabolites, autoimmunity, or protein aggregates (for example a-synuclein-rich Lewy Bodies in Parkinson's disease). Microglia are the immune cells activated in response to these cues, but other immune cells can also participate in neuroinflammation

Neurology:

A branch of medicine dealing with the diagnosis and treatment of disorders of the nervous system.

Neuromelanin: 

The dark pigment made from oxidized metabolites of monoamine neurotransmitters including dopamine and norepinephrine, found in neurons enriched with these amines, namely the substantia nigra and locus coeruleus, respectively. Neuromelaningives thesubstantia nigra (Latin for "black substance) its black appearance.

Neuromodulator:

A chemical substance other than a neurotransmitter, released by a neuron at a synapse that either enhances or dampens their activities.

Neurological conditions:

Disorders caused by damage or malfunctioning of the brain or nervous system.

Neurologist: 

A doctor who specializes in the diagnosis, care, and treatment of disorders of the brain or nervous system.

Neuroplasticity: 

The ability of the brain to change and form new connections even with aging. It involves neurons regenerating anatomically or functionally after partial injury or changing (such as by making more numerous or more effective connections) in response to training and experience.

Neuron:

A nerve cell that is the fundamental unit of the brain and nervous system. Neurons transmit information through electrochemical signals.

Neurophysiology: 

The study of the electrical activities of the nervous system. Perhaps the best-known example is recording from the brain using an EEG in epilepsy.

Neuroprotection: 

Mechanisms within the nervous system that would protect neurons from dying due to a degenerative disease or from other types of injury.

Neuroprotective:

Serving to protect neurons from injury or degeneration or an effect that may result in salvage, recovery, or regeneration of the nervous system, its cells, structure, and function.

Neuropsychology: 

The study of how the structure and function of the brain influence behavior and cognition.

Neurosurgeon: 

A doctor who specializes in using surgery to treat disorders of the brain or nervous system

Neuroscience:

The scientific study of the nervous system that deals with the anatomy, biochemistry, molecular biology, and physiology of neurons and neural circuits.

Neurotransmitter: 

A chemical messenger in the nervous system that permits communication between two neuronal cells, often but not always across a synapse. The neurotransmitter is usually released from the nerve terminals on the axons. Examples of neurotransmitters include dopamine, acetylcholine, adrenaline, noradrenaline, serotonin, glutamate, and GABA.

Neurotrophic factors: 

A family of biomolecules that support the growth, survival, and differentiation of both developing and mature neurons.

Nicotine:

A stimulant that acts as an agonist at nicotinic receptors, which are one kind of receptor for acetylcholine. Nicotine is present in cigarette smoke and has been shown to decrease the chances of developing Parkinson's disease.

Non-motor symptoms: 

Symptoms that do not involve movement, coordination, physical tasks, or mobility, including an impaired sense of smell, constipation, sleep disturbances, mood disorders, orthostatic hypotension, bladder problems, sexual problems, excessive saliva, weight loss or gain, vision and dental problems, fatigue, depression, fear and anxiety, skin problems, and cognitive issues. See motor symptoms.

Objective measurements:

The repetition of a unit amount that maintains its size, within an allowable range of error, no matter which instrument, intended to measure the variable of interest, is used and no matter who or what relevant person or thing is measured.

Occupational therapist:

Occupational therapists are concerned with assessing a person's home or work situation and then devising ways to make them more manageable and less hazardous. They can also advise on aids and equipment and leisure activities.

Olfactory dysfunction: 

An impaired ability to detect odors, and impaired sense of smell. Thought to be an early sign of Parkinson's disease but can occur in many situations not related to Parkinson's.

Oligodendrocyte:

A type of glial cell with the major role of producing myelin, a protein that coats neuronal axons, enabling fast transfer of neuronal signaling (via action potentials).

On and Off:

The clinical states of PD while being treated with levodopa, which commonly causes clinical fluctuations after a few years of treatment. The "on" state is when the PD symptoms and signs are reduced by levodopa. The "off" state is when a patient has not taken levodopa or when its benefit has been reduced or lost. The most common type of "off" is wearing-off, due to the levodopa's benefit not lasting more than a few hours after a dose. Sudden and unpredictable "off" states can also occur but are less common. "Off" states usually will respond to another dose of levodopa. Clinical fluctuations are considered a complication of levodopa therapy.

Organoid:

A miniature, simplified version of an organ that shows realistic micro-anatomy and enables the study of the complex multicellular interactions of an organ, in the dish. They are derived from tissue, embryonic stem cells, or induced pluripotent stem cells and are now being used to model brain and other neural structures- e.g., the midbrain dopaminergic nerve cells found in the substantia nigra.

Orthostatic hypotension:

A drop in blood pressure when a person is standing. It can be a complication of medications but can sometimes be due to Parkinson's itself.

Oxidative stress: 

See Reactive Oxidative Species.

Paradoxical kinesia:

The ability to move as a response to an unexpected stimulus, occurring in a person who previously could not move so easily. Paradoxical kinesia can occur in Parkinson's disease e.g. suddenly being able to run when there is a fire.

Parkin:

A protein that is generated by the Parkin gene. With homozygous (both alleles affected) Parkin mutations (PARK2 gene), Parkinson's disease develops. It is the most common cause of juvenile-onset PD and is very slowly progressing.

Parkinson-plus syndromes: 

A group of neurodegenerative diseases featuring the classical features of Parkinsonism (rigidity, akinesia/ bradykinesia, postural instability, and less commonly tremor) with additional features that distinguish them from typical Parkinson's disease. Parkinson-plus syndromes include multiple system atrophy (MSA), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD). They do not generally respond to dopamine medications.

Parkinsonism: 

A group of neurological diseases whose features include slowness and paucity of spontaneousmovement (bradykinesia), rest tremor, rigidity of the muscles, loss of postural reflexes, flexed posture, and freezing of gait.

Parkinsonian gait: 

With bradykinesia, gait is slow, short-paced, and with a tendency to shuffle, associated with decreased arm swing. Freezing of gait can also occur in Parkinsonism.

Pathogenesis: 

The underlying biologic mechanism responsible for a disease.

Peripheral blood mononuclear cell (PBMC):

Any blood cell having a single, round nucleus, i.e., white blood cells (lymphocyte, monocyte, macrophage, natural killer cell, dendritic cell) which are a critical component in the immune system to fight infection and adapt to intruders. Many studies in PD investigating peripheral inflammation look at patient PBMCs.

Peripheral Nervous System: 

The nervous system outside the brain and spinal cord.

Phenotype:

The observable characteristics of an organism or person, such as appearance, development, and behavior. Determined by the interaction between the genotype and the environment. In Parkinson's, it means what the patient looks like to the observer.

Phosphorylation: 

A process that modifies proteins by adding one or more phosphates. For proteins that function as enzymes, this results in activating or deactivating their function.

Pill-rolling tremor: 

A characteristic tremor in Parkinson's patients where the thumb and forefinger involuntary move in a way that resembles rolling a small object such as a pill.

PINK-1:

An abbreviation for the name of a gene that encodes a particular serine/threonine kinase found in mitochondria that stops stress-related cell destruction. With homozygous (both alleles affected) PINK-1 mutations, juvenile or early-onset Parkinson's disease can develop. Lack of PINK-1 causes an overload of calcium in mitochondria and indirectly cell death. The substantia nigra is particularly sensitive to PINK-1 mutations.

Physiotherapist: 

Physiotherapists use physical means such as exercise and manipulation to help prevent or reduce stiffness in joints and restore muscle strength. They can also advise on aids and equipment to help with movement problems.

Placebo:

​A simulated or inert form of treatment without known proven benefit on a symptom or a disease. A pill serving as a placebo is colloquially called a "sugar pill". Placebos are employed in controlled clinical trials along with the active drug being tested; patients and health professionals involved in the trial do not know who receives the placebo or the drug. The difference in responses between the two drugs is considered the true effect of the active drug. Surgical trials can also utilize a placebo arm in which sham or simulated surgery is performed in the control group. Sometimes placebos provide benefits; it is called a placebo effect.

Positron emission tomography (PET): 

A medical imaging technique in which radioactive isotopes that emit gamma rays are used. The radioactive substance is incorporated into a chemically active compound (a radiotracer, which could be a substrate for an enzyme or a ligand that binds to neurotransmitter receptors) utilized by an organ in the body. The emitted gamma rays are detected by a special camera/scanner. These radioactive strikes on the camera are analyzed by a computer to produce an image to localize where that ligand is located in the organ being studied Fluorodeoxyglucose (FDG) measures the regional metabolism of glucose (sugar); fluorodopa (F-DOPA) is taken up in dopamine nerve terminals. The amount of uptake serves as a measure of the integrity of these nerve terminals. Other radiotracers may bind to neurotransmitter receptors (including those for dopamine) or to inflammatory cells, etc.

Postural instability: 

Difficulty with balance leading to a tendency to fall over.

PPMI - Parkinson's Progression Markers Initiative:

A study launched in 2010 by the Michael J Fox Foundation to find biomarkers for PD; it is a landmark observational clinical study to comprehensively evaluate people with Parkinson's disease and those at greater risk of developing the disease, as well as healthy controls.

Prodromal: 

Refers to the period before the classic manifestation of a disease leading to diagnosis.

Progressive Supranuclear Palsy (PSP):

A rare degenerative brain disorder that causes serious and progressive problems with control of gait and balance, along with complex eye movement and thinking problems. A classic manifestation of the disease is the inability to move the eyes properly. PSP is one of the Parkinsonplus syndromes, though it is associated with accumulation of Tau protein (tauopathy), rather than a-synuclein.

Protestasis: 

A combination of the words protein and homeostasis. It is the concept that there are biological pathways within cells that control the creation, folding, tracking, and degradation of proteins present within and outside the cell.

Proteosomes:

Protein complexes that degrade unneeded or damaged proteins.

Protein:

1. A class of food necessary for the growth and repair of the body tissues-sources of proteins include fish, meat, eggs, and milk. 2. Large biomolecules or macromolecules consisting of long chains of amino acid residues. Within organisms, proteins catalyze metabolic reactions (enzymes), replicate DNA, and transport molecules.

PwP:

Person with Parkinson's or People with Parkinson's.

Reactive oxygen species (ROS): 

Chemically reactive molecules containing oxygen that may trigger cell death. These are also called oxyradicals. These molecules are a cause of oxidative stress that may play a role in the pathogenesis of cell death of dopamine neurons. Oxyradicals are formed during regular cellular and mitochondrial metabolism. Defense mechanisms include naturally occurring reducing agents to neutralize the oxyradicals.

Receptor:

A protein structure typically embedded in the cell membrane with which neurotransmitters, other proteins (ligands), and drugs interact.

REM (rapid eye movement) sleep behavior disorder (RBD):

A sleep disorder that involves movement and abnormal behavior during the sleep phase with rapid eye movements - the stage of sleep in which dreaming occurs. In normal sleep, muscles are paralyzed during dreaming, except for eye movements. In RBD, muscles are not paralyzed so that the dreamer acts out his or her dreams. RBD is common in people with an alpha synucleinopathy such as Parkinson's disease or Multiple System Atrophy.

Restless leg syndrome (RLS):

A neurological disorder characterized by unpleasant sensations in the legs, like the feeling of ants crawling underneath the skin. These sensations usually occur in the late evening and during sleep. Walking around relieves the sensation, hence the term "restless legs." RLS interferes with sleep and is common in people with PD. Medications, such as dopamine agonists, levodopa, and opioids, can be effective treatments.

Rigidity:

A special type of muscle stiffness, which is one of the main symptoms of Parkinson's disease. The muscles tend to pull against each other instead of working smoothly together.

Schwab and England Activities of Daily Living (ADL) Scale:

An estimation of the abilities of a person's  degree of independence. The person (or a family member) can self-assess this as: 

-100% - Completely independent. Able to do all chores without slowness, difficulty, or impairment

-90% - Completely independent. Able to do all chores with some slowness, difficulty, or impairment. May take twice as long to complete.

-80% - Independent in most chores. Takes twice as long. Conscious of difficulty and slowing.  -70% - Not completely independent. More difficulty with chores. 3 to 4 times longer to complete chores for some. May take a large part of the day for chores.

-60% - Some dependency. Can do most chores, but very slowly and with much effort. Errors, some impossible.

-50% - More dependent. Help with 1/2 of chores. Difficulty with everything.

-40% - Very dependent. Can assist with all chores but few alone.

-30% - With effort, now and then does a few chores alone or begins alone. Much help is needed -20% - Nothing alone. Can do some slight help with some chores. Severe invalid state

-10% - Totally dependent, helpless.

-0% - Vegetative functions such as swallowing, and bladder/ bowel function are not functioning. Bedridden.

Seeding assay:

This is a relatively new technology that enables small amounts of a protein that is prone to aggregate to be amplified so that it can be better detected. This is now being looked at in Parkinson's around alpha-synuclein.

Senescence:

A process in cells that stops them from dividing. It gets activated when certain types of damage occur, sometimes referred to as biological aging. The senescence-associated secretory phenotype (SASP) is a growing area of research in neurodegenerative disease research.

Serotonin: 

A neurotransmitter that regulates mood, appetite, and sleep. It also has some cognitive functions, including memory and learning. The serotonin-containing neurons are in the brain stem. Serotonin is reduced in PD.

Shaking palsy: 

Prior term for Parkinson's disease, originally used by James Parkinson when he described this condition in 1817.

Side effects:

A reaction to drugs, which is additional to the intended therapeutic actions. These unwanted extra effects are called side effects. Side effects vary in their severity from person to person, and often disappear when the body becomes used to a particular drug.

Sign (clinical sign)/Symptom:

A finding on neurological examination- e.g. stiff muscles- to be distinguished from a symptom which is what the patient reports (unable to do fine movements with my hands).

Single photon emission computed tomography (SPECT):

A nuclear medicine tomographic imaging technique using gamma rays and able to provide 3D information, for instance on brain chemistry.

Sleep apnea:

A sleep disorder characterized by abnormal pauses in breathing or instances of abnormally low breathing during sleep. Associated with PD and increased motor symptoms in PD It can be obstructive (something is reducing air intake) or central (something is not right with the respiratory in the brain). It is diagnosed typically in sleep clinics.

Sodium channel:

Voltage-gated channels in nerve cell membranes that allow the generation of action potentials. Sodium ions are important in generating the electrical impulses that travel down the dendrites and axons. After sodium enters the cell during this process, it needs to be pumped back out, via the so-called sodium-pump, a process that requires the utilization of cellular energy.

Stem cells:

Cells found in all multicellular organisms, that can divide (through mitosis) and differentiate into diverse specialized cell types and can self-renew to produce more stem cells. They are a potential line of treatment in Parkinson's, either by directly replacing the old nigrostriatal neuronal cells or by creating growth factor-releasing cells. Stem cells are also a valuable model for research of many diseases, as stem cells can be generated from patient somatic cells that retain their genetic identity- thus you can grow nerve cells from patients with Parkinson's typically via an IPSC intermediate.

Striatum:

A large cluster of nerve cells that are part of the basal ganglia. The striatum consists of two parts: the caudate nucleus and the putamen. It controls movement, balance, and some elements of thinking; the striatum receives nerve inputs from many parts of the brain including dopamine neurons from the substantia nigra and glutamate neurons from the cerebral cortex. Acetylcholine and GABA neurons are located within the striatum. GABA neurons also send signals outside the striatum. The striatum contains the largest concentration of dopamine and acetylcholine in the brain.

Substantia nigra: 

(Latin for black substance). A brain structure located in the midbrain that plays an important role in movement. Parts of the substantia nigra appear darker than neighboring areas due to high levels of neuromelanin in dopaminergic neurons. The substantia nigra is the site of the brain's major collection of dopamine neurons, which project their axons to the striatum, the so-called nigrostriatal pathway. These neurons slowly die in PD. The substantia nigra is part of the basal ganglia; the other parts of the basal ganglia include the striatum (caudate nucleus, putamen), globus pallidus, and subthalamic nucleus. The substantia nigra is made up of two parts: the pars compacta and the pars reticulata.

- Pars compacta: The part of the substantia nigra primarily involved in Parkinson's. It contains dopamine neurons, and it is black due to the high concentration of neuromelanin within these neurons. (Parkinson's disease is characterized by the death of dopaminergic neurons in the substantia nigra pars compacta.)

-Pars reticulata: Part of the substantia nigra that serves both as the location of dendrites from the Pars compacta, receiving nerve signals to the substantia nigra, and also as an output, conveying signals to numerous other brain structures. These output neurons are mainly GABAergic neurons.

Subthalamic nucleus (STN):

​A small lens-shaped nucleus involved in movement control. As suggested by its name, the subthalamic nucleus is located below the thalamus. It is part of the basal ganglia. It receives input from the cerebral cortex and the globus pallidus interna. It sends its output mainly to the globus pallidus externa and substantia nigra pars reticulata. It is a component of the "indirect pathway" within the basal ganglia. It is "overactive" in PD due to the loss of inhibitory incoming fibers. It is a common target in deep brain stimulation for PD.

Shuffling gait: 

Refers to short, slow steps, with feet close to the ground or dragging along the ground. This gait is often seen in people with advanced Parkinson's disease.

SWEDD- Scans Without Evidence of Dopamine Deficit:

When individuals with early-stage Parkinson's disease have normal dopaminergic functional imaging scans (see DAtScan).

Synapse:

The connecting structure between two neurons (axon to dendrite) or between a neuron and a muscle. Axons release neurotransmitters at the nerve terminal. The neurotransmitter crosses the synapse to activate or inhibit another nerve cell by acting on a receptor on the dendrite.

Synaptic plasticity: 

The ability of synaptic activity to modify and adapt to changes.

Syndrome:

A group of symptoms that tend to occur together and which reflect the presence of specific disorders or diseases. Parkinson syndrome, also called Parkinsonism, comprises a group of disorders with symptoms and signs in common, such as bradykinesia, rigidity, tremor, loss of postural reflexes, flexed posture, and freezing of gait. A person with Parkinsonism does not need to have all of these but must have bradykinesia according to one diagnostic criterion. Disorders that fall within Parkinson syndrome include Parkinson's disease, atypical Parkinsonism, Parkinson Plus Syndromes (e.g., PSP, MSA), drug-induced Parkinsonism, and normal pressure hydrocephalus.

Synucleinopathy: 

A class of neurodegenerative disease resulting from pathological accumulation of alpha-synuclein in neurons (Parkinson's, Lewy Body Dementia) or a kind of glia cells called oligodendrocytes (Multiple System Atrophy).

Tau proteins: 

Proteins that stabilize microtubules, which are structural entities in axons. They are abundant in neurons in the central nervous system and are less common elsewhere. When tau proteins are defective and no longer stabilize microtubules properly, they can result in dementia (including Alzheimer's disease). This protein may also play a role in Parkinson's.

Tauopathies:

A class of neurodegenerative diseases resulting from the pathological aggregation of tau protein in so-called neurofibrillary tangles (NFT) in the human brain. Besides Alzheimer's, this is commonly seen in progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD).

Thalamotomy: 

​A now uncommon surgical procedure used to treat Parkinson's tremor in which a small portion of the brain area called the thalamus is destroyed.

Thalamus:

A midline paired symmetrical structure situated between the cerebral cortex and brain stem, both in terms of location and neurological connections. It is composed of many regions with distinct functions. For example, some thalamic regions relay sensory signals to the cerebral cortex, others relay signals from the basal ganglia to the cerebral cortex, and others relay motor signals from the cortex to the spinal cord and brain stem.

Toxicity: 

​The degree to which a chemical substance or a particular mixture of substances can damage an organism.

T.R.A.P.:

Acronym for four primary Parkinson's disease symptoms:

-Tremor: Shaking of limbs (usually hands) while they are at rest.

-Rigidity: Muscle stiffness and resistance to movement.

-Akinesia/bradykinesia: Difficulty initiating voluntary body movements/Slowed ability to start and continue movements.

-Postural instability: Loss of postural stability can cause falls and produce a feeling of unsteadiness.

Transcranial Magnetic Stimulation:

A method in which a changing magnetic field is used to cause an electric current to flow to a small region of the brain and thus briefly modulate its function.

Transcription factors: 

Proteins in eukaryotes (cells which contain complex membrane-bound structures within the cell) that regulate the transcription (i.e. the expression) of genes.

Translation:

A step in protein biosynthesis wherein the genetic code transferred from DNA to messenger RNA (mRNA) is decoded to allow the formation of a protein molecule. The process is preceded by the transcription of the DNA into the mRNA.

Tyrosine: 

An amino acid used by cells to synthesize proteins. It is also the precursor of dopamine.

Ubiquitin: 

A small regulatory protein that is composed of 76 amino acids. It is involved in the degradation of damaged proteins. In Parkinson's disease, it is believed that accumulation of damaged proteins "choke" the cell, leading to the eventual death of the cell.

Unified Parkinson's Disease Rating Scale (UPDRS):

A rating scale used to measure the severity of Parkinson's disease. The UPDRS can follow a person's worsening over time and measure improvement with various treatments. The UPDRS is made up of the following sections:

-Part I: Evaluation of mentation, behavior, motivation, and mood

-Part II: Self-evaluation of the activities of daily life (ADLs) including speech, swallowing, handwriting, dressing, hygiene, falling, salivating, turning in bed, walking, cutting food

-Part III: Clinician-scored motor evaluation

-Part IV: Measures some of the adverse effects (such as motor complications of "off" states and dyskinesias) of levodopa therapy in Parkinson's disease.

The UPDRS has been modified by the Movement Disorder Society to include more non-motor features of PD. This new version is called MDS-UPDRS.

Vagus nerve:

The vagal nerves carry signals between your brain, heart, and digestive system. They are a key part of your parasympathetic nervous system. Vagus nerve damage can lead to gastroparesis, food not moving into your intestines. Some people with vasovagal syncope faint from low blood pressure. Vagus nerve stimulation (VNS) can treat epilepsy and depression.

Ventral Tegmental Area (VTA):

A group of neurons located in the midbrain next to the substantia nigra and involved in cognition and motivation, including reward and addiction.

Vesicle:

An organelle in a cell that separates some molecules from the rest of the cell. In nerve terminals, the vesicles are called synaptic vesicles. They store neurotransmitters, which are released into the synapse when the nerve fires. 

Wearable Devices:

Devices worn on the body, incorporating computers, electronics, software, and/or sensors, often used to measure some aspect of function or physical manifestation, for example: activity trackers, accelerometers, gyroscopes,etc.

Wearing Off:

The loss of the effectiveness of Parkinson's medication between dosing resulting in the return of symptoms.