Glossary

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D

DC inhibitors:
Drugs that block decarboxylase, one type of enzyme that breaks down dopamine. Also called AADC inhibitors, they include carbidopa and benserazide.

Decarboxylase:
A category or subclass of enzymes that removes or eliminates a molecule of carbon dioxide from a carboxylic group. Carbidopa is an inhibitor of the decarboxylation of levodopa.

Deep brain stimulation:
A surgical procedure that involves implanting a device into the brain that blocks the brain signals that cause tremor.

Degenerative:
(1) Describes a gradual wearing away or breaking down of cells/tissue in the body, characteristic of diseases such as Alzheimer's and multiple sclerosis, as well as the general process of aging. (2) Marked by or pertaining to deterioration; particularly, deterioration of the function or structure of tissue or changes from a higher to a lower or less functionally active form.

Delirium:
A state of frenzied excitement or wild enthusiasm.

Delusions:
(1) A condition in which the patient has lost touch with reality and experiences hallucinations and misperceptions. (2) Delusions are fixed beliefs about events or circumstances that have no basis in reality.

Dementia:
According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), dementia can be diagnosed if the patient has impaired memory and at least one of the following cognitive deficits: To be diagnosed as dementia, these cognitive deficits must significantly affect a person's social or occupational functioning and represent a significant decline from previous levels of functioning. And the deficits must not result exclusively from delirium. Delirium comes on suddenly, and in addition to memory impairment, is characterized by attention deficits, impaired consciousness, and perceptual problems like hallucinations or delusions.

Dementia-nuchal dystonia:
Another name for Progressive Supranuclear Palsy.

Demyelination:
A process in which the myelin around nerve cells gets stripped away, leaving the nerve cell bare and susceptible to temporary and permanent damage.

Dendrite:
The relatively narrow, branching projections that extend from the cell bodies of neurons. Nerve cells may contain multiple dendrites, which are stimulated by neurotransmitters, receive impulses from the nerve fibers (axons) of other neurons, and convey them toward their nerve cell bodies.

Dentatorubropallidoluysian atrophy (DRPLA):
A rare genetic disorder that is most commonly described in Japan. Associated symptoms may become apparent in adolescence or adulthood. Early-onset disease may be characterized by rapidly progressive neurodegenerative changes, including seizures, cognitive impairment, and brief, "shock-like" muscle spasms of certain muscles or muscle groups (myoclonus). Late-onset disease may be associated with progressively impaired control of voluntary movement (ataxia) and symptoms often seen in Huntington's disease (HD), including chorea and gradual loss of thought processing and acquired intellectual abilities (dementia). Brain imaging studies typically reveal degenerative changes of the globus pallidus and specialized nerve cell clusters within the cerebellum (dentate nucleus). Similar to HD, the disorder may result from abnormally long sequences or "repeats" of particular coded instructions (unstable expanded CAG repeats) within a gene (located on chromosome 12). Also known as DRPLA, Dentatorubral-Pallidoluysian Atrophy or Naito-Oyanagi Disease.

Deprenyl:
(Eldepryl, Selegiline, Jumex) A drug that slows the breakdown of chemicals like dopamine by inhibiting the action of certain enzymes. It increase effects of dopamine in the brain.

Detoxification:
The process the liver uses to break down harmful substances in the body, such as toxins, drugs, and waste products, to render them harmless and eliminate them from the body.

DHEA:
An important hormone produced in the adrenal glands, the body's primary source for the production of the sex hormone testosterone. Peak levels of DHEA are reached in an individual's early to mid-20s. Optimal levels are associated with increased energy, healthy immune and cardiovascular function, improved memory and elevated mood.

DHEA-S:
The sulfate form of the hormone DHEA. The body stores over 95% of DHEA in the sulfate form, DHEA-S.

Dietician:
An individual trained in diet and nutrition.

Differential diagnosis:
Distinguishing between two or more diseases and conditions with similar symptoms by systematically comparing and contrasting their clinical findings, including physical signs, symptoms, as well as the results of laboratory tests and other appropriate diagnostic procedures.

Diosgenin:
A saponin found in the roots of plants such as the yam. In the laboratory, parts of diosgenin can be cleaved in order to make certain steroids. Our body is not known to have the proper enzymes to convert diosgenin into pregnenolone, progesterone, or DHEA. Therefore, ingesting wild-yam extracts will not lead to DHEA production.

Disease-modifying therapy:
Targets harmful immune responses in MS. It can change the course of MS by slowing it down. Studies show that disease-modifying therapy is most helpful when taken early in the course of MS.

Diuretics:
Medications that promote the excretion of urine. Such medications are often prescribed to help reduce excess fluid levels in the body, such as associated with chronic heart failure, high blood pressure (hypertension), or certain kidney (renal) or liver (hepatic) disorders. Diuretics help to remove excess water from the body by increasing the amount that is excreted as urine.

DME:
Durable medical equipment. Medical supplies that are durable, not disposable. Insurance companies use this term often. Examples of DME include walkers, wheelchairs.

DNA:
Deoxyribonucleic acid. DNA is a spiraling, ladder-like (helical) molecule that is the carrier of the genetic code. Nucleic acids are the primary components of the chromosomes within the nuclei of cells. DNA is also found in mitochondria, the rod-like structures outside the nuclei of cells that function as a primary source of cellular energy.

Docosahexaenoic acid (DHA):
A member of the Omega-3 family of essential fatty acids. The body makes DHA from the primary Omega-3, alpha linolenic acid. DHA is found in high quantities in cold-water fish and marine animals.

Dopa Decarboxylase:
An enzyme present in the body that converts levodopa to dopamine.

Dopa Decarboxylase Inhibitors:
Drugs that block the conversion of levodopa to dopamine outside the brain. These include carbidopa and benserazide.

Dopamine:
A chemical substance in the brain, a neurotransmitter essential to the proper functioning of the central nervous system. It regulates movement, balance, walking and tells your muscles what to do. Dopamine assists in the effective transmission of electrochemical messages from one nerve cell to the next. It is deficient in the basal ganglia and Substantia Nigra of a person with Parkinson's disease and this keeps muscles from working properly.

Dopamine Agonist (DA):
Drugs that mimic the effects of dopamine and stimulate the dopamine receptors. DAs combine with dopamine receptors to mimic dopamine actions. Such medications stimulate dopamine receptors and produce dopamine-like effects.

Dopamine Autoreceptor:
A type of dopamine receptor that acts like a thermostat, preventing excess dopamine release as levels rise.

Dopamine Receptor:
A molecule on a receiving nerve cell (neuron) that is sensitive (or receptive) to stimulation (arousal) by dopamine or a dopamine agonist. At least five types have been identified including D1, D2, D3 receptors and the dopamine autoreceptor.

Dopamine Receptor Antagonist:
A pharmacologic agent that binds to and blocks the action of dopamine receptors, essentially hindering receptor activity by preventing stimulation by dopamine.

Dopamine Transporter:
Dopamine is a chemical in the body that allows one nerve cell to send a message or signal to another nerve cell and helps to control movement. After dopamine finishes sending its message, a substance called a dopamine transporter carries the dopamine back from the nerve ending to the cell that produced it so that the dopamine can be reused. The number of dopamine transporters is a sign of the number of nerve endings that produce or release dopamine.

Dopaminergic:
(1) An adjective used to describe a chemical, a drug, or a drug effect related to dopamine. (2)Having the effect of dopamine or related to dopamine-producing cells.

Dopaminergic drug:
A dopaminergic drug is any drug that has the effect of dopamine. Levodopa is converted in the body to dopamine, and dopamine agonists mimic the effects of dopamine at the receptors.

Dopaminergic Dysfunction:
Malfunction of dopamine receptors.

Double-Blind:
(1)A research study where neither the researchers nor the volunteers know who's getting the medicine and who's getting the placebo until the code is broken at the end of the study. (2)A clinical experiment in which neither the patients nor the researchers are aware of which patients are receiving the active treatment and which are receiving placebo.

DRPLA
Dentatorubral-Pallidoluysian atrophy (DRPLA) is a progressive disorder of ataxia, choreoathetosis, and dementia or character changes in adults and ataxia, myoclonus, epilepsy, and progressive intellectual deterioration in children. The age of onset is from one to 62 years with a mean age of onset of 30 years. The clinical presentation varies depending on the age of onset. The cardinal features in adults are ataxia, choreoathetosis, and dementia. Cardinal features in children are mental retardation, behavioral changes, myoclonus, and epilepsy. Also known as Dentatorubral-Pallidoluysian Atrophy or Naito-Oyanagi Disease.

Drug:
As defined by the Food, Drug and Cosmetic Act, drugs are "articles (other than food) intended for the use in the diagnosis, cure, mitigation, treatment, or prevention of disease in man or other animals, or to affect the structure or any function of the body of man or other animals."

Drug Holiday:
A 3 to 14 day withdrawal of a drug after long term treatment.

Drug Induced Parkinsonism:
Parkinson's symptoms which have been caused by drugs used to treat other conditions, e.g., neuroleptic drugs, and reserpine, used to be used to treat hypertension

Drug Product:
A consumer focused drug dosage form (e.g. tablet, capsule, or solution) that contains the active drug ingredient usually combined with inactive filler ingredients.

Duodenum:
The duodenum is the part of the small intestine that is connected to the stomach.
Durable Medical Equipment (DME):
Equipment that is primarily serving a medical purpose, is able to withstand repeated use, and is appropriate for use in the home; for example, wheelchairs, oxygen equipment and hospital beds. To be covered by Medicare, durable medical equipment must be prescribed by a doctor. Many types of adaptive equipment are not covered.

Durable Medical Equipment Medicare Administrative Contractor (DME MAC):
A private insurance company that has a contract with Medicare to process durable medical equipment (DME) claims. DME MACs follow Medicare national guidelines to decide on a local level what types of equipment should be covered on a case-by-case basis, and how much Medicare will pay for the equipment. There are four DME MACs in the United States, each covering several states. Any questions regarding your DME coverage should be directed to your local DME MAC for answers. You can reach your local DME MAC by calling 800-MEDICARE (800-633-4227).

Durable Medical Equipment Regional Carrier (DMERC):
The former name of DME MACs (Durable Medical Equipment Medicare Administrative Contractors), until September 2007.

Dysarthria:
(1) Disordered or impaired articulation of speech due to disturbances of muscular control, usually resulting from damage to the central or peripheral nervous system. Dysarthria is associated with certain neurodegenerative disorders, such as Parkinson's disease or Huntington's disease; cerebral palsy; brain tumors or stroke; or certain types of brain surgery. (2) Speech difficulties caused when the muscles associated with speech are affected. (3) Difficulty in forming words or speaking them because of weakness of the muscles used in speaking or because of disruption in the neuromotor stimulus patterns required for accuracy and speed of speech.

Dysbiosis:
The state of a disordered microbial ecology that causes disease. It may exist in the oral cavity, gastrointestinal tract or vaginal cavity. In dysbiosis, normally harmless bacteria, yeasts, and protozoa trigger disease by altering the nutrition or immune responses of their host.

Dysfunction:
Body parts or body systems that either don’t function the way they should if they were healthy or have difficulty doing what they are supposed to do.

Dysesthesias:
Unpleasant sensations that are produced in response to normal stimuli.

Dysinsulinemia:
A state characterized by abnormal insulin levels in the blood.

Dyskinesia:
An abnormal involuntary movement that results in jerky or repetitive motions. Dyskinesias are common in many neurologic movement disorders including late Parkinson's disease (PD), restless legs syndrome, etc. Dystonia, athetosis, and chorea are types of dyskinesia.

Dyskinesias:
Abnormal neuromuscular conditions characterized by disorganized or excessive movement (also known as hyperkinesia). Forms of dyskinesia include sudden, brief, "shock-like" muscle contractions (myoclonus); involuntary, rhythmic, oscillatory movements of a body part (tremor); rapid involuntary jerky movements (chorea); relatively slow writhing motions (athetosis); or abrupt, purposeless, simple or complex muscle movements or vocalizations (motor or vocal tics).

Dyskinesias While Awake (DWA):
Uncontrolled, sporadic movements of the legs and, in some cases, the arms. These movements may be very rapid (myoclonic) or quite slow and prolonged (dystonic); they usually disappear upon voluntary action. Some researchers suspect that these movements may represent a wakeful form of periodic limb movements in sleep (PLMS).

Dysphagia:
(1) Difficulty in swallowing. Dysphagia may be associated with esophageal obstruction as well as certain neurodegenerative or motor disorders involving the esophagus.(2) A swallowing disorder that is characterized by difficulty in oral preparation for the swallow or moving material from the mouth to the stomach. This also includes problems in positioning food in the mouth.

Dysphasia:
Language disorder; the inability to speak words which one has in mind or to think of correct words; or inability to understand spoken or written words.

Dyspraxia:
Partial loss of the ability to coordinate and perform certain purposeful movements and gestures in the absence of motor or sensory impairments.

Dystonia:
(1) A neurologic movement disorder characterized by sustained muscle contractions, resulting in repetitive, involuntary, twisting or writhing movements and unusual postures or positioning. Dystonia may be limited to specific muscle groups (focal dystonia), such as dystonia affecting muscles of the neck (cervical dystonia or spasmodic torticollis) or the eyes, resulting in closure of the eyelids (blepharospasm). Dystonia is associated with certain underlying genetic disorders, such as dystonia musculorum deformans, dopa-responsive dystonia, and paroxysmal kinesigenic and paroxysmal non-kinesigenic dystonic choreoathetosis. The condition may result from the use of certain medications, lack of oxygen during or immediately after birth, or other causes of brain trauma. (2) Involuntary spasms of muscle contraction that cause abnormal movements and postures. May appear as a side effect of long term drug treatment in Parkinson's and may worsen in response to stress. (3) The condition of sustained contractions or spasms of muscles of the shoulders, neck, and trunk. It frequently causes twisting and repetitive movements or abnormal postures. Often this is due to disease involving the basal ganglia of the brain.

Dystonic:
Referring to dystonia; sudden jerky or repetitive movemfor OAents and muscle spasms due to impaired muscle tone and abnormal muscle rigidity.

Dystrophin:
A protein; a chemical substance made by muscle fibers.

DYT-1 dystonia:
The DYT-1 gene regulates or "encodes" production of a protein called torsinA. Although its specific function is not know, torrsinA appears to be related to a class of proteins that enable cells to recover from injury or stress. The change, or mutation, that causes DYT-1 dystonia involves one of a pair of three basic chemical "building blocks" of DNA. These are called guanine, adenine, and guanine, or "GAG" trinucleotides and are part of the genetic code within the DYT-1 gene. The specific mutation that occurs in DYT-1 dystonia is an absence, or deletion, of GAG. This relatively tiny change in the blueprint for torsinA apparently causes critical changes in the function of the protein and may lead to the symptoms of dystonia.

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Document last modified:06/18/08 07:13:20 AM