According to the article, mild cognitive impairment is a less severe form of impairment than is dementia. Perhaps because of the lesser degree of severity, mild cognitive impairment is usually noticeable to the patient's family members. It may be a precursor to Alzheimer-type dementia.

Constantine G. Lyketsos, M.D., M.H.S., and colleagues studied the prevalence of neuropsychiatric symptoms in the prior month among patients with dementia and mild cognitive impairment who were enrolled in the Cardiovascular Health Study Cognition Study, a cohort study of individuals at least 65 years old randomly sampled from lists in four American communities.

Of 682 individuals with dementia or mild cognitive impairment, 43 percent of patients with mild impairment (n=138) exhibited neuropsychiatric symptoms in the previous month: Depression (20 percent), apathy (15 percent), and irritability (15 percent) were most common. Among the dementia patients, 75 percent (n=270) had a neuropsychiatric symptom in the previous month, with 55 percent (n=199) reporting two or more symptoms and 44 percent (n=159) reporting three or more disturbances in the prior month. In patients with dementia, the most common disturbances were apathy (36 percent), depression (32 percent), and agitation/aggression (30 percent).

"These findings confirm previous estimates of high prevalence of neuropsychiatric symptoms in dementia, with 60 percent of participants with dementia exhibiting clinically significant symptoms in the past month, and more than 80 percent exhibiting any symptom from the onset of cognitive impairment," write the authors.

The authors conclude: "Clinical evaluations of patients with suspected mild cognitive impairment and dementia must include specific assessment of and treatment for such symptoms. This also has significant implications for further studies of the pathophysiology and treatment of neuropsychiatric symptoms in cognitively impaired elderly people."