Longitudinal diagnosis of memory disorders.

Early referral for specialist assessment is becoming more common with memory disorders and dementia: the mean Mini-Mental State Examination (MMSE) score of new patients at our clinic rose from 18.7 to 20.7 between 1986 and 1990. The clinical diagnosis of mild to moderate dementia has been recognized to be difficult, but several studies have reported cross-sectional diagnosis. We examined the number of visits required to establish a clinical diagnosis of dementia in the first 125 patients attending a Memory Disorders Clinic who had at least two visits (six months apart) and the stability of the diagnoses. Just under half of the patients required at least two visits to establish the clinical diagnosis. The MMSE was not a good guide to the number of visits required but the diagnosis at the first visit remained stable in all patients who scored < or = 10/30. Sixteen per cent of patients interchanged between the categories of Alzheimer's, mixed and vascular dementias. Possible age-associated memory impairment progressed to dementia in six of eight cases, and depression to dementia in three cases. The diagnosis of mild to moderate dementia should not be restricted to a cross-sectional approach, but should involve serial clinical, psychological and affective assessments.