Parkinson's Disease Glossary
A guide to the scientific language of Parkinson's disease for the non- scientist
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Acetylcholine: One of the chemical
neurotransmitters in the brain and other areas of the central and peripheral
nervous system. It is highly concentrated in the basal ganglia, where it
influences movement. It is located in other regions of the brain as well, and
plays a role in memory. Drugs that block acetylcholine receptors (so-called anticholinergics)
are utilized in the treatment of PD.
Agonists: A chemical or drug that can
activate a neurotransmitter receptor. Dopamine agonists, such as pramipexole,
ropinirole, bromocriptine and apomorphine, are used in the treatment of PD.
Akinesia: Literally, means loss of
movement. It is usually interchangeably with bradykinesia (see below).
Alpha-synuclein: A protein present in nerve
terminals. The accumulation of this protein is a pathologic finding in PD. The
gene (SNCA) was the first genetic
mutation found in PD, and was called PARK1. Alpha-synuclein also accumulates in
multiple system atrophy (MSA) and in Lewy Body Disease. Alpha-synuclein appears to play a key role in
the pathogenesis of PD.
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's 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, in particular in the formation of memories involving
Anticholinergics: A type of medication that interferes
with the action of acetylcholine (see
above). Examples include:
- benztropine mesylate
- biperiden hydrochloride
- orphenadrine citrate
- procyclidine hydrochloride
- trihexyphenidyl hydrochloride.
Antagonists: Has the opposite effect
from an agonist (see above).
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.
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
Autonomic Nervous System
of the peripheral nervous system, consisting of sympathetic and parasympathetic
nerves that control involuntary actions, in particular the heart, smooth muscle
(such as bladder and blood vessels) and glands.
Autosomal: Refers to all the
chromosomes excluding the sex-related X and Y chromosomes.
Autosomal recessive: A mode of inheritance of
genetic traits located on the autosomes that only becomes manifest when two
copies of a mutated gene (two alleles) are present. In order 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 2 different abnormalities of
the same are inherited, that can result in recessive inheritance.
Axon: A nerve fiber that carries
electrical impulses from the nerve cell body to other neurons. 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 (see above) is deposited in long, thin axons, and these are called
Basal ganglia: Clusters of neurons that
include the caudate nucleus, putamen, globus pallidus and substantia nigra
which are located deep in the brain and play an important role in movement. Cell
death in the substantia nigra contributes to Parkinsonian signs.
Biomarker: An early indicator that a
person may have a disease, such as Parkinson’s. A biomarker, if present, could
indicate that the person has a disease before symptoms of that disease appear.
There is a search for biomarkers for PD. Biomarkers could be a chemical,
clinical, physiologic or imaging finding.
Blood brain barrier: The separating membrane
between the blood and the brain; a tight physical barrier that normally keeps
immune cells, chemicals and drugs out of the brain.
Bradykinesia: Literally, means slowness
of movement. It is commonly used synonymously with akinesia and hypokinesia.
Bradykinesia is a clinical hallmark of Parkinsonism.
Brain stem: The part of the brain between
the cerebral hemispheres and 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. The substantia nigra, which is damaged in
Parkinson's, is located in the midbrain of the brain stem.
Calcium: An essential mineral. Calcium
is important for neurological "signaling" and is
involved in many chemical reactions within neurons and in mitochondria function.
Calcium overload in substantia nigra has been postulated as one mechanism that
could contribute to death of these neurons.
Carbidopa: A drug given with levodopa.
Carbidopa blocks the enzyme dopa decarboxylase, thereby preventing levodopa
from being metabolized to dopamine. Because carbidopa does not penetrate the
blood brain barrier (see above), it only
blocks levodopa metabolism in the peripheral tissues and not in the brain,
thereby reducing side effects but increasing the effectiveness of levodopa.
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.
Cerebellum: Part of the hind brain;
controls smooth movements. When damaged, it results in ataxia (see above).
Cerebrospinal fluid (CSF): A watery fluid generated
within the brain's ventricles and circulates to bathe the brain and spinal cord
to cushion these from physical impact.
Chronic: (opposite: acute) Chronic
diseases are of long duration. Chronic diseases are typically of subtle onset
and slow worsening over time. The term does not imply anything about the
severity of a disease.
CNS: abbreviation of Central
Nervous System, which consists of the brain, brain stem and spinal cord.
Cognition: Mental processes including
attention, remembering, producing and understanding language, solving problems
and making decisions.
Cognitive: Relating to mental activity
such as thinking, reasoning, making judgments and remembering.
Computed tomography (CT): A medical imaging method
employing computer processing to produce images seen as slices through the
tissue. This presentation of images is known as tomography.
(catechol-O-methyltransferase): One of the enzymes that break down
dopamine, adrenaline (also called epinephrine) and noradrenaline (also called
therapeutic concept for the management of Parkinson's disease that proposes
that continuous (as opposed to discontinuous or pulsatile) stimulation of
striatal dopamine receptors will delay or prevent the onset of levodopa-related
Cytokines: A number of small proteins
that are secreted by specific cells of the immune system and carry signals
locally between cells, and thus have an effect on other cells. Higher levels of
pro-inflammatory cytokines are found in Parkinson’s brains. Unlike growth
factors, they have no specific role in cell proliferation and are primarily
linked to blood and immune cells. Cytokines have also been known to be involved
in causing cell death.
Deep Brain Stimulation
surgical treatment that involves the implantation of a medical device (electrical
stimulator) that acts as a brain pacemaker sending electrical impulses to the specific
area in which the electrode was inserted. In Parkinson’s patients the device is
typically inserted in either the subthalamic nucleus or the globus pallidus,
less often in the thalamus or pedunculopontine nucleus, depending upon the
Dementia: A decline in cognitive
function due to damage or disease in the brain beyond what might be expected
from normal aging. Areas particularly affected include memory, attention, judgment,
language, planning and problem solving.
- Alzheimer's disease dementia: The most common
form of dementia, typically presents with difficulty in remembering names and
events. May also initially include apathy and depression, and later
impaired judgment, disorientation, confusion, behavior changes and
difficulty speaking, swallowing and walking. Associated with abnormal deposits of the
protein fragment beta-amyloid (plaques) and twisted strands of the protein
tau (tangles) as well as brain nerve cell damage and death.
- Dementia with Lewy bodies (DLB): Similar, but not
identical, symptoms as in Alzheimer’s dementia. DLB commonly has a greater
occurrence of sleep disturbances, well-formed visual hallucinations, and
muscle rigidity. Associated with aggregation of alpha-synuclein in the cerebral
cortex. Lewy bodies are also a pathologic hallmark in Parkinson's disease.
The relationship of DLB and PD remains to be resolved.
- Parkinson's dementia: Presents similarly to Alzheimer’s
dementia or dementia with Lewy bodies, but is typically preceded by clinical
Parkinson's disease. Associated with alpha-synuclein aggregates that are
more likely begin in the brain stem, including the substantia nigra.
Dendrites: (from Greek meaning,
"tree”) Nerve fibers that project from the nerve cell body. Branches of
dendrites are the receiving fibers of signals coming to the neuron from other
neurons and convert these chemical signals into electrical ones to the nerve
state of low mood. Some consider it a dysfunction, while others see it as an
adaptive defense mechanism.
DJ-1: Mutations in this gene
cause an autosomal recessive form of Parkinson’s disease. The function of the
protein created by DJ-1 appears to reduce oxidative stress.
(such as carbidopa) that inhibit the metabolism of levodopa to form dopamine.
By inhibiting dopa decarboxylase only in the peripheral organs (not CNS),
levodopa concentration is increased and more can enter the brain. These drugs are
particularly useful in Parkinson’s when used with levodopa.
Dopamine: A small chemical molecule that
is one of the brain's neurotransmitters. It is found particularly in cells
within the substantia nigra. These cells project to the striatum in the basal
ganglia. Deficiency of dopamine causes symptoms of Parkinsonism.
Dopamine agonist: A compound that activates
dopamine receptors, other than dopamine. Examples include, bromocriptine mesylate
(Parlodel), pergolide (Permax), pramipexole (Mirapex), ropinirole hydrochloride
(Requip), piribedil, cabergoline, apomorphine (Apokyn), rotigotine (Neupro
patch) and lisuride. These act like dopamine, but are not actually dopamine.
They can be used in both the early and late stages of Parkinson’s disease. They
are the second most powerful type of anti-Parkinson medication after levodopa.
They can cause side effects such as sleepiness, sleep attacks, ankle swelling,
hallucinations and impulse control problems, more commonly than levodopa does.
Dopaminergic pathways: Neural pathways in the
brain which utilize dopamine as their neurotransmitter. There are four major
groups: the nigrostriatal, mesocortical, mesolimbic and tuberoinfundibular
- Nigrostriatal: Connects the substantia nigra to
the striatum. Involved heavily in Parkinson’s.
- Mesocortical: Connects the ventral tegmental area
(adjacent to the substantia nigra) to the cerebral cortex. Closely
associated with the mesolimbic pathway.
- Mesolimbic: Connects ventral tegmental area to nucleus
accumbens, amygdala & hippocampus and prefrontal cortex. Along with
the mesocortical pathway, is involved in memory, motivation, emotional
response, reward and addiction. Can cause hallucinations and schizophrenia
if not functioning properly.
- Tuberoinfundibular: from hypothalamus to
pituitary gland involved in hormonal regulation, maternal behavior
(nurturing), pregnancy and sensory processes.
Dysarthria: Impaired speech function.
Dyskinesia: Abnormal involuntary
Dysphagia: Difficulty in swallowing.
Embryonic stem (ES) cells: see stem cells
Entacapone: A Parkinson’s drug that is
used alongside levodopa and carbidopa. It inhibits the enzyme COMT, decreasing the
breakdown of levodopa.
Festination: An involuntary quickening of
the gait; the acceleration of gait
noted in Parkinsonism and similar disorders, literally means "chasing the center
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
principal inhibitory neurotransmitter in human brain. GABA neurons are rich in the
striatum, globus pallidus, substantia nigra and cerebellum.
GDNF: see growth factors
Gene therapy: The insertion of genes into
an individual's cells and tissues to treat hereditary diseases where deleterious
mutant alleles can be replaced with functional ones. 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 (Glial cells): Non-neural cells, commonly called neuroglia or
simply glia (Greek for "glue"), that maintain homeostasis, form
myelin, and provide support and protection for the brain's neurons.
Globus pallidus: A major part of the basal
ganglia involved in movement control. Split into two main parts: the internal
globus pallidus (GPi), and the external globus pallidus (GPe). Deep brain stimulation
of the GPi is shown to have an increase in motor function in Parkinson's patients
and to reduce dyskinesia.
Glutamate: An amino acid and the main
excitatory neurotransmitter in the human brain. The major input to the striatum
is from the cerebral cortex. These corticostriatal neurons use glutamate as
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.
- Glial cell line derived nerve growth factor (GDNF): Thought
to promote the health of dopamine neurons.
- Brain-derived nerve growth factor (BDNF): Also
supports dopamine neurons.
- Fibroblast growth factor (FGF): Studies have found
a possible genetic link to Parkinson’s disease on the FGF20 gene.
- Vascular endothelial growth factor-B (VEGF-B): May
have neuroprotective affects in Parkinson’s disease.
Heterogeneity: Lacking uniformity in
composition or character. (As opposed to homogeneity, which is uniformity in
composition or character.)
Hippocampus: A complex neural structure
(shaped like a sea horse) located in the temporal lobes of the brain; involved
in memory storage and in 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
- 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
Hyperkinesia: An abnormal increase in
movement and/or muscle activity; synonymous with dyskinesia.
Hypokinesia: Literally means reduced
amplitude of movement. It is commonly used synonymously with akinesia and
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 control of digestion, the immune
system, mood, sexuality and energy storage and consumption.
Hypothalamus: A portion at the bottom of
the middle of the brain that links the limbic system to the pituitary gland and
is a master area for the autonomic nervous system.
Idiopathic: Arising from an unknown
Impulse control disorder
of psychiatric disorders characterized by an inability to control one’s
actions, in particular 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.
Leucine rich repeat kinase 2
protein created by the LRRK2 gene which when mutated can lead to Parkinson’s. Several
different disease causing LRRK2 gene variants have been found in Parkinson’s
patients, but there may also be variants within the general population that do
not necessarily cause disease.
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.
Lewy bodies: A pathologic hallmark of
Parkinson's disease and dementia with Lewy bodies. First described by Frederic Lewy,
Lewy bodies are seen microscopically as inclusions in neurons in several brain
regions, including the substantia nigra and locus ceruleus. One protein seen is
alpha-synuclein in an aggregated form. Aggregates of this protein in axons are
called Lewy neurites.
Magnetic resonance imaging
noninvasive medical imaging technique to visualize detailed internal structure
and limited function of the body. MRI provides much greater contrast between
the different soft tissues of the body than computed tomography (CT), making it
especially useful in neurological (brain), musculoskeletal, cardiovascular and
oncological (cancer-related) 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 so-called
"cheese effect" because tyramine can be found in high concentrations
in some soft cultured cheeses.
- MAO B inhibitors: These drugs (e.g. selegiline,
rasagiline) inhibit the breakdown of dopamine via MAO-B enzyme and do not
cause the "cheese effect” of hypertension.
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.
Microglia: A type of glial cell; it
provides the first immune defense mechanism in the brain and central nervous
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. (Also see: non-motor
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.
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 ceruleus, respectively. Neuromelanin gives the substantia nigra (Latin
for "black substance") its black appearance.
Neuromodulator: A chemical substance other
than a neurotransmitter, released by a neuron at a synapse and either enhances
or dampens their activities.
Neuroprotection: Mechanisms within the
nervous system that would protect neurons from dying due to a degenerative
disease or from other types of injury.
Neurotransmitter: A chemical messenger in the
nervous system that permits communication between two neuronal cells, normally
across a synapse. The neurotransmitter is released from the nerve terminals on
the axons. Examples of neurotransmitters include dopamine, acetylcholine,
adrenaline, noradrenaline, serotonin, glutamate, and GABA.
Nicotine: A stimulant that acts as an
agonist at nicotinic receptors in the brain. Smoking, which contains nicotine,
has been associated with a decreased chance of developing Parkinson’s disease.
Non-motor symptoms: Symptoms that do not
involve movement, coordination, physical tasks or mobility, including loss of
sense of smell, constipation, sleep disorders or 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)
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 the 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 4 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.
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 Parkinsonism
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.
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.
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).
Parkinsonism: A group of neurological
diseases whose features include slowness and paucity of spontaneous movement
(bradykinesia), rest tremors, 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.
PINK-1: An abbreviation for the
name of a gene that encodes serine/threonine kinase, an enzyme 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 shown to be particularly sensitive to PINK-1 mutations.
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." When
placebos provide benefit, it is called a placebo effect. Placebos are employed
in controlled clinical trials along with the active drug being tested. 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. The mechanism of how
placebos provide benefit may be associated with release of dopamine in the
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 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.
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 Parkinson-plus syndromes.
PwP: Person with Parkinson's.
Reactive oxygen species
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 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 the
eye movements. In RBD, muscles are not paralyzed so that the dreamer acts out
his or her dreams. RBD is common in people with Parkinson's disease or MSA.
Restless leg syndrome (RLS):
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.
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
large part of 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 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,
bladder/bowel function are not functioning. Bedridden.
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.
Single photon emission
computed tomography (SPECT): A nuclear medicine tomographic imaging
technique using gamma rays and able to provide 3D information, for instance on
Sleep apnea: A sleep disorder
characterized by abnormal pauses in breathing or instances of abnormally low
breathing during sleep.
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. Sodium channels may be a target for new
drugs in Parkinson's.
Stem cells: Biological 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. Problems have arisen due to the inability to stop growth,
which may cause tumor growth.
Striatum: A large cluster of nerve
cells that are part of the basal ganglia. The striatum consists of two sectors:
the caudate nucleus and the putamen. It
controls movement, balance, and walking; 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 neurons are
located within 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
reward, addiction, and 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, and nucleus accumbens), 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 from the globus pallidus interna. It sends
its output mainly to the globus pallidus externa and interna. It is a component
of the "indirect pathway" within the basal ganglia. It is
"overactive" in PD due to 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.
Synapse: The narrow space 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 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 a specific disorders
or diseases. Parkinson syndrome, also called Parkinsonism, comprise 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,
drug-induced Parkinsonism, and normal pressure hydrocephalus.
proteins: Proteins that stabilize microtubules. 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).
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 Pick's disease, progressive supranuclear
palsy (PSP) and corticobasal degeneration (CBD).
Thalamus: A midline paired
symmetrical structure situated between the cerebral cortex and brain stem, both
in terms of location and neurological connections. It relays sensory signals to
the cerebral cortex and motor signals from the cortex to the spinal cord and
T.R.A.P.: Acronym for four primary
Parkinson's disease symptoms:
- Tremor: Shaking of limb (usually hands) while they
are at rest.
- Rigidity: Muscle stiffness and resistance to
- Akinesia/bradykinesia: Slow movement or difficulty
initiating voluntary body movements; Slowed ability to start and continue
- Postural instability: Loss of postural stability
can cause falls and produce a feeling of unsteadiness.
Transcription factors: Proteins in eukaryotes (cells
which contain complex membrane-bound structures within the cell) that regulate
the transcription 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
blood pressure caused by an increase in tyramine in the blood, which forces noradrenaline/norepinephrine
out of vesicles and into circulation. This is the so-called "cheese
effect" because some fermented cheeses (and other foods) contain high
concentrations of tyramine. Normally, tyramine is broken down in the gut by
MAO-A. When this enzyme is inhibited, the tyramine in food is able to enter the
blood stream and produce its hypertensive crisis.
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
also measure improvement with various treatments. The UPDRS is made up of the
- Part I: Evaluation of mentation, behavior, motivation
- 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
UPDRS has been modified by the Movement Disorder Society to include more
non-motor features of PD. This new version is called MDS-UPDRS.
Vesicle: An organelle in a cell
that separates other 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.