The diagnosis of dementias of the Alzheimer type.

There are a large number of people with primary degenerative dementia of the Alzheimer type throughout the world. This number will continue to increase during the next century, and will represent a major health problem for future generations. The diagnosis of the dementia is based on the presence of disturbances in higher cortical functions, cognition, language or behaviour, and the presence of apraxia and agnosia. To determine the etiology of the dementia, a number of investigations are required; these include neurological examination, use of diagnostic criteria, assessment instruments and measurement of mental functions, electroencephalography, and imaging techniques. Diagnosis is generally obvious in the middle stages of the disorder, but may be difficult or even hazardous in the early stages. This is a major handicap for research investigations. At present, emission tomography is the only technique which identifies abnormalities in the early stages of the disorder and which differentiates primary degenerative dementia from multi-infarct dementia. For the time being, this technique is still too sophisticated and costly to be used on a regular basis, but it will prove indispensable in the identification, understanding and early treatment of dementia.