In a catchment area survey, 43 patients with cognitive impairment acquired in the presenium associated with behavioural or social dysfunction, or both, were identified. Twelve of 18 carers were also interviewed. The patients were mainly in their 50s, had a high prevalence of behavioural as opposed to cognitive disorder, were frequently taking psychotropic drugs and had disorders which were largely progressive. Those living at home were as disabled as those living in residential settings. Carers were stressed but uncomplaining. The findings suggest that psychiatrists, perhaps especially old age psychiatrists, have an important role in developing services for this neglected group of people.