Brain & Ageing

• Define ageing


  The failure to maintain homeostasis under physiological stress
• Characteristics of ageing

  • Progressive loss of physiological integrity
  • Leading to impaired function
  • increase vulnerability to death
• Physiological changes with ageing

  • neuronal loss
  • formation of neurofibrillary tangles of aggregates of hyper-phosphorylated tau proteins inside neurons
  • formation of senile plaques, e.g. beta amyloids from tissue degeneration. it deposits at the extracellular space between neutrons of brain
• 2 types of intelligence

  • Fluid intelligence: Ability to improve organisation of information, generate new hypothesis, and reasoning & abstraction. Decreases with age.
  • Crystallised intelligence: Ability to apply previous experiences with new conditions. Increases with age.
• State the effects of aging on memory

  with increasing age, it takes more time & effort to encode information
• Main effect of aging on brain volume

  • brain volume decreases after 65 years old
  • there is greater decrease in white matter than grey matter
  • the decrease in white matter & cognitive impairment leads to decrease in speed of mental processes, attention, concentration, executive function, and visual spatial skills
• Give 3 biochemical changes in ageing

  1. cholinergic neurons, there is decrease in cholinergic neurotransmitters causing deterioration of cognition associated with age & Alzheimer's disease
  2. dopaminergic neurons, there is steady decline in dopaminergic cells in substantia nigra with age. This leads to shuffling gait & stooped posture
  3. noradrenergic neurons, decrease in noradrenergic neurons causes attention decline. B2 receptors decline with age in cerebral cortex, this increases incidence of depression in elderly
• 3 major functional changes in ageing

  • reduction in speed of attention, executive function
  • learning capacity & problem solving skills slows down
  • muscle weakness & wasting
  • increase risk of falls