Dementia

The commonest aetiologies of dementia are: Alzheimer’s disease, Vascular and Lewy body dementia.

– These conditions are difficult to diagnose and there are many assessment tools e.g. GPCOG, abbreviated mental test score (AMTS) and the mini-mental state examination (MMSE)

Investigation pathway:

– 1st do a cognitive assessment e.g. MOCA

– Exclude reversible causes – do FBC, U&E, LFTs, calcium, glucose, TFT, Vit B12 and folate (2)

– Imaging – CT head (structural causes) and MRI (vasculature changes) 

Alzheimer’s disease

The number one cause of dementia in the UK is Alzheimer’s disease. The disease is characterised by a progression degeneration of the cortex and typically occurs sporadically and in the elderly.

– Early onset AD can be seen in families (autosomal dominant mutation in presenilin) + Down’s syndrome

– Pathogenesis of the disease is controversial however it is known that the degradation product of amyloid precursor protein, B-amyloid peptide accumulates, giving rise to amyloid plaques.

– In addition, tau proteins are know to coalesce to form neurofibrillary tangles destroying ACh neurones

Symptoms:

– Memory loss (loss of memory is slow and progressive- beginning with short-term memory and later affecting long term episodic memory)

– Learned motor and language skills lost over time

– Changes in behaviour (aggression) and personality

Diagnosis:

This is based on clinical suspicion once other diseases have been ruled out

Management:

Vascular Dementia

This is one of the most common types of dementia which occurs due to degeneration of the brain secondary to cardiovascular risk factors

– It leads to multifocal infarction in parts of the brain over a period of time leading to cognitive decline

Symptoms:

Memory loss over time

Patients may have a stepwise deterioration (e.g. after TIA/cardiovascular event)

Diagnosis:

CT/MRI scan

Management:

Control cardiovascular risk factors e.g. diabetes management, hypertension

Do not use drugs that are used in Alzheimer’s disease (e.g. AChE inhibitors)

A type of dementia which is related to Lewy Body deposition in the substantia nigra, limbic and neocortical areas. This leads to features of both Alzheimer’s disease and Parkonsons

Symptoms:

Triad of decreasing memory + Visual hallucinations + Parkinsonism ie bradycardia or rigidity

– REM sleep behaviour disorder. 

This is a type of frontotemporal dementia which classically affect the frontal and temporal lobe.

– It accounts for 20% of the cases of young onset dementia and is the third most common type of dementia.

– Pick bodies (round aggregates of tau protein) collect in the lobes and cause destruction of neurones.

Symptoms:

– Gives early personality change + impaired social conduct + disinhibition + increased appetite

– Age of onset before 65 + progresses slowly though there is preserved memory/visuospatial skill