It is neither practical nor essential to perform all the screening tests in every patient with dementia. The presenting features should guide investigations.
DEMENTIA Suspected cause
Alzheimer's disease -
Appropriate investigations without neurological signs or systemic illness with neurological signs
(gait disturbance and incontinence)
with neurological signs and systemic symptoms and signs with 'stroke risk factors' (page 236)
with poor nutrition with metabolic and endocrine symptoms and signs with history of head trauma
Degenerative disease, -
e.g. Huntington's chorea
Normal pressure hydrocephalus -Frontal lobe tumour
Inflammatory disease, — e.g. Demyelinating disease (page 499) Vasculitis & collagen vascular disease
Infective disease, -
Metabolic and endocrine disease
Confirmation: pathology (biopsy)
CT/MR scan Genetics Confirmation: pathology (biopsy or post mortem)
Confirmation: CSF pressure monitoring (tumour-biopsy)
Serum autoantibodies Evoked responses CSF (immunology) CT/MR scan
Serum antibodies (viral) VDRL, TPHA HIV status CSF examination CT/MR scan
Serum Bt (thiamine) Red cell transketolase (thiamine)
Serum Bn2 Serum folate
Neuropsychometric testing is performed:
- to diagnose early dementia
- to separate true dementia from pseudodementia
- to monitor progress or trials of treatment.
When the reason for dementia is unclear, comprehensive investigation is essential to ensure that treatable nutritional, infective, metabolic and structural causes are not overlooked.
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