Acetylcholine: neurotransmitter; synaptic transmission of signals between neurons and muscles, but also in the brain. In AD, lower than usual acetylcholine levels can be found.
Agnosia: lack of ability of recognition of objects, people, smells, sounds, and shapes; usually classified with regard to the affected sense(s).
Apagia: lack of ability of being able to swallow.
Amyloid: protein found in the brains of people with Alzheimer’s disease; deposited throughout the brain in microscopic aggregations (see: plaque). Its function is not known, neither is proven unambiguously that it is the cause (not just a marker) of dementia.
Amyloid precursor protein: (abbr.:APP) precursor of amyloid beta into which APP is cleaved by the protease activity of γ-secretases.
Antagonist: substance that counteracts or nullifies the action of another substance; as a drug: binds to a receptor without eliciting a biological response.
Aphasia: difficulty of understanding what others say and/or expressing oneself verbal; complete or near complete absence of speech (compare: see: dysphasia).
Apoptosis: main type of programmed cell death, carried out as an ordered process that confers advantages during an organism’s life cycle.
Apraxia: inability to carry out a skilled or learned motor function, not related to paralysis or lack of comprehendsion, but caused by cortical lesions.
Atrophy: decreasing in size, shrinking; here: loss of brain mass.
ß-amyloid: see: amyloid.
Behavioural symptoms: symptoms that relate to action or emotion; characteristic of the moderately severe to severe stages of AD where the patients show behavioural changes, namely: wandering, aggression, agitation, hostility, sleep disturbances.
Cognitive functions: mental functions such as memory, learning, reasoning, planning, thinking, and remembering.
Cognitive symptoms: dysfunction of cognitive functions. In AD patients, they are the defining early symptoms, namely loss of memory, confusion and aphasia.
Cyclooxygenase: (abbr.: COX) enzyme that is responsible for formation prostanoids (e.g. prostaglandins, thromboxane); COX inhibition can provide relief from inflammation and pain; well-known COX inhibitors: aspirin, ibuprofen.
Dysphasia: lack of coordination in speech; failure to coordinate words in understandable way; caused by brain lesions; not (yet) as severe as aphasia.
Dyspraxia: impaired function of any organ of the body.
Encephalopathy: any degenerative disease of the brain.
Excitotoxicity: toxic effect of excitatory neuronal action, may ultimately lead to neuronal death.
γ-secretase: enzyme that snips off pieces of the amyloid precursor protein producing fragments of amyloid.
Glutamate: amino acid neurotransmitter; highest concentration in the hippocampus where glutamate is by far the most abundant excitatory neurotransmitter; critically involved in learning and memory processes. Pathological excess of glutamate can lead to excitotoxicity, i.e. it will eventually cause neuronal death, e.g. in the situation of Alzheimer’s disease.
Hippocampus: part of the limbic system; essential for learning and memory as information is processed in the hippocampus for long-term memory storage; area of the brain where long-term potentiation takes place.
Ischemic: affected by ischemia, i.e. by a low oxygen state due to obstruction of the arterial blood supply or inadequate blood flow.
Limbic system: heterogeneous array of brain areas at or near the edge of the medial wall of the cerebral hemisphere; mainly one of its parts, the hippocampus, is essential for learning and memory functions; exerts an important influence upon the endocrine and the autonomic motor systems; affects motivational and mood states;
Long-term potentiation: increased strength of transmission at a synapse, triggered by repetitive use over more than a few minutes.
Mitochondrium: organelle of eukaryotic cells, often described as “cellular power plants”; convert organic materials into energy in the form of ATP.
MK-801: experimental non-competitive NMDA receptor antagonist.
Myoclonus: twitching or spasm of a muscle (group).
N-methyl-D-aspartate: short: NMDA; subtype of glutamate receptors, implicated in learning and memory as well as in neuronal cell death, ischemia and epilepsy.
NSAID: non-steroidal anti-inflammatory drug, i.e. analgesic, antipyretic or anti-inflammatory substance.
Neurodegeneration: gradual deterioration of brain and nerve tissue.
Nucleus basalis magnocellularis: (also: N. basalis, N. basalis of Meynert) group of cells at the base of the frontal lobe containing many cholinergic neurons.
Parietal lobe: part of the brain positioned behind the temporal lobe; integrates information coming from various senses; involved in visuo-spatial processing and manipulation of objects.
PCP: phencyclidine; non-competitive NMDA receptor antagonist.
Plaque:(also: neuritic plaque, amyloid plaque); abnormal cluster of dead or dying neurons, other brain cells (glia) and fragments of amyloid; one of the hallmarks of Alzheimer’s disease: Upon autopsy, the presence of amyloid plaques and neurofibrillary tangles is used to positively diagnose AD.
Quinolinic acid: 2,3-pyridinedicarboxylic acid, a metabolite of tryptophan; possible role in neurodegenerative disorders: Elevated levels of quinolinic acid in the cerebro-spinal fluid of AIDS patients are significantly correlated with the severity of their neuropsychological deficits.
Striatum: subcortical area of the brain, part of the basal ganglia; takes part in planning and modulation of movement pathways as well as executive functioning.
Synaptic cleft: space between the two neurons of a synapse which needs to be bridged (chemically) by neurotransmitters in order to propagate any presynaptic (electrical) signal further towards the postsynaptic neuron.
Tangles: (also: neurofibrillary tangles), accumulation of pathologically hyperphosphorylated Tau protein within neurons. Microscopically, tangles can be identified as a characteristic histolpathological hallmark of Alzheimer’s disease and is used upon autopsy to confirm the diagnosis of AD.
Temporal lobe: lobe at lateral-anterior area of the cerebrum; governs and regulates e.g. memory and recognition, sense of smell, sexual expression.
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