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Aging of the Nervous System: Functional Changes. P.S. Timiras. Acetic acid. Choline. AChE inhibitor. Acetylcholinesterase Inhibition. Presynaptic nerve terminal. Muscarinic receptor. Postsynaptic nerve terminal. Nicotinic receptor. Acetylcholine (ACh). Acetylcholinesterase (AChE).
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Aging of the Nervous System:Functional Changes P.S. Timiras
Acetic acid Choline AChE inhibitor Acetylcholinesterase Inhibition Presynaptic nerve terminal Muscarinic receptor Postsynaptic nerve terminal Nicotinic receptor Acetylcholine(ACh) Acetylcholinesterase(AChE) Nordberg A, Svensson A-L. Drug Safety. 1998;19:465-480.
Again, in the normal aging brain the changes are relatively few. However impaired function and increased pathology do occur. Major functional deficits/ pathologies involve: Motility (e.g. Parkinson’s Disease) Senses and communication Cognition (e.g. dementias) Affect and mood (e.g. depression) Blood circulation (stroke, multi-infarct dementia) Parkinson’s Disease: Chapter 8, pp. 110-113 Dementias: Chapter 8, pp. 130-136
Control of Posture, Balance and Mobility Skeletal Muscles Bones and Joints Hormones Blood Circulation Central Nervous System • Cerebral Cortex • Basal Ganglia • Cerebellum • Vestibular-ocular & proprioceptive pathways • Limbic System • Spinal Cord
With aging, normal adult gait changes to: • Hesitant • broad based • small stepped • Stooped posture • Diminished arm swings • Turns performed en bloc • With Parkinson’s, there is also: • Rigidity • Tremors (at rest) • Akinesia (loss of power of movement) • Bradykinesia (slowed movement) • Pathology of Parkinson’s entails: • Presence of Lewy bodies • Loss of dopaminergic neurons in the substantia nigra
Definition of Dementia Dementia (from the Latin de-mens, without mind) is a clinical syndrome that refers to a global deterioration of intellectual and cognitive functions characterized by a defect of all five major mental functions: • Orientation • Memory • Intellect • Judgment • Affect But with persistence of a clear consciousness.
Dementia (cont.) • There are two types of dementia: • Reversible • Irreversible
From Table 8.10
For further information on brain plasticity in old age and factors which may enhance this plasticity, see the below papers (full texts are available on the course website under “Relevant Articles”): • Merabet LB et al. What blindness can tell us about seeing again: merging neuroplasticity and neuroprostheses. Nat Rev Neurosci 2005, 6(1) 71-77. • Adlard PA et al. Voluntary exercise decreases amyloid load in a transgenic model of Alzheimer's disease. J. Neuroscience 2005, 25(17), 4217-4221. • Colcombe S, Kramer AF. Fitness effects on the cognitive function of older adults: a meta-analytic study. Psychol Sci 2003, 14(2), 125-130. • van Praag H et al. Exercise enhances learning and hippocampal neurogenesis in aged mice. J Neuroscience 2005, 25(38), 8680-8685.