Psychiatric symptoms such as depression and irritability often affect elderly Alzheimer patients as well as those suffering from other forms of dementia, according to researchers at Johns Hopkins Hospital.

Researchers developed a study to estimate the prevalence of psychiatric symptoms in 682 patients with dementia or mild cognitive impairment. The participants were evaluated with data collected over a ten-year period in four U.S. counties. A total of 362 subjects were classified as having dementia and 320 were classified as having mild cognitive impairment.

A total of 43 percent of the patients with mild cognitive impairment showed psychiatric symptoms during the previous month, with 29 percent rated as clinically significant. The most common symptoms were depression (20 percent), apathy (15 percent) and irritability (15 percent).

There were no differences in the prevalence of psychiatric symptoms between participants with Alzheimer's disease and those with other dementias, with the exception of abnormal motor behavior, which was more frequent in the Alzheimer's disease patients, the researchers reported in the Journal of the American Medical Association.

Among the patients with dementia, 75 percent showed a psychiatric symptom during the previous month, with 62 percent rated as clinically significant. Fifty-five percent showed two or more psychiatric symptoms and 44 percent showed three or more psychiatric symptoms. The most common symptoms of this group were apathy (36 percent), depression (32 percent) and agitation/aggression (30 percent).

"Neuropsychiatric symptoms occur in the majority of persons with dementia over the course of the disease," concluded the researchers. "These symptoms have serious adverse consequences and should be inquired about and treated as necessary."

Other sources: Journal of the American Medical Association