ABSTRACT
Research psychiatrists in the 1950s and 1960s produced remarkably consistent prevalence rates for moderate and severe dementia by interviewing subjects in a flexible, semi-structured fashion and basing their diagnoses on textbook descriptions. The prevalence of mild, moderate and severe dementia combined was 10.5 per cent and rates increased steadily with age, from 4.1 per cent in subjects aged 75-79 years to 32.6 per cent in subjects aged 90 years and over. Mild dementia is a particularly contentious area, and prevalence rates depend to a large degree on the methods used to diagnose it. Initial Cambridge Mental Disorders of the Elderly Examination (CAMDEX) interviews were conducted by psychiatrists, all of whom had practical experience in caring for elderly patients. CAMDEX diagnoses of minimal dementia posed considerable difficulties and only a small proportion of subjects had deteriorated further when seen a year later.
