The first epidemiologic study of dementia in the United States has corroborated the findings of previous research in a United Kingdom population-based study, as well as several U.S. studies of specific demented patients. Researchers conclude that mental and behavioral disturbances are core components of dementia, regardless of the cause of the dementia, or the stage of advancement.

The study, by lead author Constantine G. Lyketsos, M.D., an associate professor of psychiatry at Johns Hopkins University Medical School, appears in the May issue of the American Journal of Psychiatry. Lyketsos and his colleagues looked at 5,092 residents of Cache County, Utah. They represented 90 percent of the county’s population aged 65 or older.

Of the more than 5,000 elderly residents, 329 who screened positive for dementia and 673 who screened negative for dementia underwent comprehensive examinations. Each was given the Neuropsychiatric Inventory, a widely used method for identification and classification of mental and behavioral disturbances associated with dementia.

Of the 329 subjects with dementia, 65 percent had Alzheimer’s disease, 19 percent exhibited vascular dementia, and 16 percent had another DSM-IV dementia diagnosis. Slightly more than 60 percent of the demented population exhibited one or more mental or behavioral disturbances in the month prior to the screening.

The researchers rated each of the study participants in the 10 domains identified by the Neuropsychiatric Inventory: delusions, hallucinations, agitation, depression, anxiety, elation, apathy, disinhibition, irritability, and aberrant motor behavior.

The point prevalence for any of the 10 disturbances was 61 percent, with apathy being the most common at nearly 30 percent. Depression, agitation, or aggression was present in one out of four subjects with dementia. The prevalence of all 10 disturbances was much higher in the demented population than in those without dementia. These findings are consistent with previous studies of Alzheimer’s disease populations. The authors noted, however, that because the study looked at prevalence only in the previous month, the cumulative prevalence of each disturbance over the course of the dementia is probably much higher

Lyketsos and his colleagues found no consistent differences among their subjects with Alzheimer’s versus vascular dementia. There was a modest indication that depression occurred more frequently in vascular dementia, and delusions and hallucinations occurred more often in Alzheimer’s subjects. This also would be consistent with previous reports.

Several disturbances, which included delusions, anxiety, apathy, irritability, and disinhibition, were reported at all stages of dementia. Aggression/agitation and aberrant motor behavior became more common as dementia progressed.

The study provides important data from a large, heterogenous population that mirrors results in smaller populations with dementia. The authors concluded that although dementia is defined by its cognitive aspects, it appears that almost all individuals with dementia exhibit mental and behavioral disturbances through the course of their dementia. These disturbances drastically add to the morbidity of dementia and must, according to the authors, be addressed as an integral part of any treatment plan.

The authors call for much needed research that explores complex treatments and focuses on a broader range of outcomes.