The investigation of dementia: results in 200 consecutive admissions.

200 patients admitted consecutively to the Neuropsychiatric Institute, Sydney, with the provisional diagnosis of dementia were investigated. The diagnosis was confirmed in 164 patients, 16 patients had a chronic organic brain syndrome not characterised by intellectual deterioration, and 20 patients had pseudodementing functional illnesses. A potentially reversible cause of the dementia was found in 13 patients: these comprised 11.5% of the demented patients aged 45 to 64 years and 3.8% of the demented patients aged 64 years and older. It is recommended that all patients with a provisional diagnosis of dementia be investigated early in the course of their illnesses in anticipation of the finding of a reversible dementia or a treatable pseudodementing illness.