Dementia

Question 1

What is dementia?

Answer 1

• A chronic and progressive deterioration of cognitive function due to organic brain disease. It is irreversible and consciousness is not impaired.

Question 2

What are the different types of dementia’s you can have?

Answer 2

1. Alzheimer’s disease (50%) - degeneration of the cerebral cortex, with cortical atrophy and reduction in acetylcholine production
    Degeneration of neurons in cortex
    Aetiology not completely known but associated with beta amyloid plaques (outside neuron) and Tau tangles (inside neuron)
    Over time this causes brain atrophy – gyri get narrows and sulci get wider and ventricles get larger
    Types: sporadic and familial
    Insidious onset, episodic memory loss, language impairment
2. Vascular Dementia (25%) - Infarction of small and medium sized vessels- essentially mini strokes (strokes/TIAs)
    Neuronal death- location specific deficit- Step wise decline
    Focal, motor and gait signs
3. Lewy Body Dementia (15%) - deposition of abnormal proteins (Lewy bodies) within the brain stem and neocortex
    Onset of cognitive impairment before Parkinsonian symptoms
    Visual hallucinations and fluctuating cognition
4. Frontotemporal Dementia - specific degeneration of the frontal and temporal lobes
    Reduced hygiene, personality change, poor planning, aphasia
   Alzheimer’s > Vascular > Lewy Body > Frontotemporal (may coexist)

Question 3

Summarise the epidemiology of dementia

Answer 3

• Prevalence increases with age
• Prevalence of 20% in patients aged > 80 yrs

Question 4

What are the presenting symptoms of dementia?

Answer 4

• All dementias
  o Progressive loss of memory and cognitive function
  1. Alzheimer’s disease - insidious onset
  o Starts with short term memory loss
  o Then motor skills decline
  o Then language affected
  o Then long term memory
  o Then disoriented
  2. Vascular dementia - step-wise decline
  3. Lewy Body dementia - fluctuating levels of consciousness, hallucinations, falls and Parkinsonian symptoms
  4. Frontotemporal dementia - behavioural changes and intellectual changes

Question 5

What are the 5 As of Alzheimer’s dementia?

Answer 5

Amnesia: remembering
Anomia: Naming
Apraxia: Doing
Agnosia: Recognising
Aphasia: Speaking

Question 6

What Investigations are used to diagnose/ monitor dementia?

Answer 6

Bedside:
1. Cognitive Assessment → Mini-Mental State Examination (MMSE, patient who scores 24 points or less is generally considered to have dementia)
24-30 (no cognitive impairment), 18-23 (mild cognitive impairment), 0-17 (severe cognitive impairment)
2. +/- MoCA and ACE assessment

Labs:
1. Blood Screen (primary care - to exclude reversible causes) → FBC, U&E, LFTs, calcium, glucose, TFTs (hypothyroidism), vitamin B12 and folate levels

Imaging:
(CT/MRI/PET - secondary care)
- Narrowed gyri, widened sulci, dilated ventricles, medial temporal vol loss & Cortical and hippocampal atrophy in Alzheimer’s on MRI
- Amlyloid plaques in Alzheimer’s in PET scan
- Lacunar infarcts (white areas on MRI) in Vascular
- Metabolic disorders and atrophy in frontal and temporal lobes in Frontotemporal
- Also look for reversible causes such as subdural haematoma.
- Lewy Body Dementia ⇒ SPECT (DATscan)

Question 7

How is dementia managed?

Answer 7

1. 1st Line (mild-moderate Alzheimer’s) → acetylcholinesterase inhibitors (donepezil, rivastigmine - if hallucinations one of main symptoms, galantamine)
   - Prolonged QT = contraindication for acetylcholinesterase inhibitors
2. 2nd Line (or for severe Alzheimer’s) → memantine (NMDA receptor antagonist, leading to decreased glutamate induced excitotoxicity)
   - Avoid antipsychotics in Lewy Body Dementia ⇒ may cause irreversible parkinsonism
3. Non-Pharmacological Treatment
   - Cognitive Stimulation Therapy → improve memory and problem solving skills
   - Cognitive Rehabilitation