History-taking in the elderly with and without cognitive impairment. How useful is it?

To assess the usefulness of interviewing older adults with cognitive impairment, we analyzed data from the NIMH Epidemiologic Catchment Area Study. People aged 65 and older with cognitive impairment were twice as likely as age-matched unimpaired elders to report sufficient symptoms of psychiatric disorders to qualify for a current diagnosis (16% vs 7%), and were also more likely to qualify for a lifetime diagnosis (25% vs 15%). We considered whether this excess could be due to random responses by the impaired, but found the rank order of their symptoms very similar to that of the unimpaired. Although dementia is thought to affect recent more than remote memory, the impaired were no less likely than the unimpaired to report disorders of recent onset. We also compared the cognitively impaired and unimpaired with respect to their reliability as assessed by reinterview one year later and found no significant difference. We conclude that there is no reason to believe that the excess of disorders in the mildly impaired is an artifact caused by their poorer performance as respondents. Interviewing the elderly person with cognitive impairment is a useful way of discovering concurrent disorders that may be treatable.