Cognitive Disorders Of Old Age Notes

Cognitive disorders of old age

Domains of age related decline

• Working memory

• Processing speed

• Long term memory

• Reasoning

But not all cognitive domains are affected by ageing

• Crystallised intelligence

• Semantic memory- fact store

• Skill learning- mirror drawing but it takes longer

Old age diseases

• Amnesia

• Dementia

• Delerium

Old age + Brain atrophy

• Hippocampal atrophy – this results in normal learning but impaired transfer

• Required for binding/compressing irrelevant information, allowing the subject to focus on relevant features

• Individuals with hippocampal atrophy can’t use the previously learned info and so treat the new problem as if it’s completely new

Changes in brain activity with ageing

• Overactivity in older relative to younger subjects- this could be due to additional recruitment of neural activity to maintain performance

• Hemispheric asymmetry reduction in older adults- due to de-differentiation where there is loss of regional specificity

• Posterior-anterior shift in aging (more activitiy) in the frontal regions of the brain)- dynamic ongoing process of plasticity

Dementia

• Definition: Set of symptoms including memory loss, mood changes and problems with communicating and reasoning

• Diagnosis

  • Multiple cognitive deficits- e.g memory and executive function

  • Functional impairment- no longer able to carry out activities of daily living

  • Clear consciousness

  • Change from previous level

  • Long duration >6 months

• Types of dementia

  • Alzheimer’s disease:

    • 60%

    • caused by amyloid plaques, tau tangles

    • medial temporal lobe, parietal lobes, sometimes frontal; hippocampal memory deficits

    • Primary episodic deficit

  • Fronto-temporal dementia

    • 5-20%

    • tau, TDP-43, FUS

    • frontal variant (behaviour)- drastic personality changes, temporal variant (semantic/aphasia)-language difficulties

  • Vasular dementia

    • 5-15%

    • vascular pathology

    • Step wise preogression

  • Dementia with lewy bodies

    • 2-8%

    • Lewy bodies

    • motor symptoms similar to Parkinosim (tremor, rigid muscles, no facial expression), sleep disturbance, visual hallucinations, fluctuating deficits (good and bad days)

• Comparisons

  • AD vs FTD : AD worse on epidosodic memory; FTD fluency tasks worse

    • Pyramids and palm trees test

      • FTD due loss of semantic memory- fail to associate palm trees with pyramids

      • AD fail to remember what they came across before

  • AD vs VaD

    • Difficult as VaD can be anywhere

    • Memory deficit in both cases although worse in AD

    • Some suggestion that perception-emotion recognition is differentially impaired in VaD

  • AD vs DLB

    • DLB-memory is intact but more visual deficit

  • However all types of dementia reveal that the standard neuropsych tests have a lot of overlap. Diagnostic boundaries not clear

• Tests for dementia

  • ...

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