Other types of dementia
Vascular dementia (multiple infarct dementia):
Intellectual decline due to an ischaemic injury to the brain. Second most common form of dementia. The cognitive decline is the result of additive effect of infarcts loss of brain tissue. Abrupt onset. Higher risk in those with diabetes mellitus, hypertension, ischaemic heart disease, stroke (increases risk 9x), smoking, falls, hyperlipidemia, early urinary incontinence ( importance of primary prevention in these populations). Deterioration is selective – some functions can remain intact, depending on location of infarcts. Similar clinical features to Alzheimer's, but onset more abrupt and has a more fluctuating course. Symptoms often develop in a stepwise fashion.
2) Two or more of:
i) Focal neurological signs
ii) Onset was abrupt, stepwise or associated with a stroke
iii) CT or MRI shows multiple infarcts
Management – not possible to reverse damage that has already occurred, but further damage may be preventable by addressing risk factors (eg control of hypertension and diabetes; anticoagulants).
Dementia associated with Lewy Body Disease
Lewy bodies (eosinophilic intracytoplasmic neuronal inclusions) are commonly associated with Parkinson’s disease. Lewy body dementia was first described in 1961 – as a diagnosis, it is increasing in incidence, but still may be poorly understood. Clinically similar to Alzheimer’s disease - loss of memory, language and reasoning and other higher brain functions. Confusion tends to fluctuate; visual hallucinations may occur.
Two of the following are needed for diagnosis of probable Lewy Body Dementia:
• fluctuating cognition with variations in attention and alertness
• recurrent visual hallucinations (usually well formed and in great detail)
• motor features of Parkinsonism
No definitive treatment, but have high sensitivity to antipsychotics
Other uncommon causes of dementia:
• toxins (eg lead)
• Vitamin deficiencies (eg B12, B1, B6)
• endocrine (eg hypo- or hyperthyroidism, hyperparathyroidism, Cushing’s disease)
• metabolic conditions (eg hyponatraemia, renal failure)
• Huntingtons disease
• vasculopathies affecting the brain
• CNS infections (eg Creutzfeldt-Jacob, AIDS)
• CNS lesions