13. Neurodegeneration

• neurodegeneration:

  • non specific = cell death
  • specific = disease specific pathology
• the effects of neurodegeneration depends on the site not the type of degeneration
• two main categories of neurodegenerative diseases:

  • disorders of movement and system degenerations
  • dementias
• dementia = acquired global impairment of intellect memory and personality without impairment of consciousness
• more plastic areas of the brain are more vulnerable to age and diseases
• about 13% of dementia cases are potentially reversible
• major cause of dementia = alzheimers disease
• alzheimers is a progressive dementia of long duration that increases in prevalence with age

  • irreversible
  • long term memory affected later in disease
  • many lose sense of smell
• alzheimers leads to significant atrophy of medial temporal lobe

  • creation of neurofibrillary tangles (develop in hippocampus and spread out) and plaques (develop in cortical areas and spread to limbic later on)
  • plaques don't correlate with severity
• multi-infarct dementia = vascular dementia

  • similar pathology to alzheimers
  • small infarcts in brain affecting white and grey matter - lack of O2 - disrupt function - sudden decline in cognitive abilities
• lewy body dementia has typical pathology of Parkinson's - blob of junk proteins that fills cell
• reducing risk of dementia:

  • lowering blood pressure mid life
  • oestrogen replacement during menopause
  • folic acid supplementation
• drugs that enhance cholinergic transmission have had marginal success on treating dementia

  • inhibit AChE