Depression and other behavior changes may be evident in individuals who will later develop Alzheimer disease, even before they start having memory problems, according to a study published online ahead of print January 14 in Neurology.

“While earlier studies have shown that an estimated 90% of people with Alzheimer disease experience behavioral or psychological symptoms such as depression, anxiety, and agitation, this study suggests that these changes begin before people even have diagnosable dementia,” said study author Catherine M. Roe, PhD, of the Washington University School of Medicine in St. Louis.

The study included 2,416 persons aged 50 and older who had no cognitive problems at their first visit to one of 34 Alzheimer disease centers in the United States. The participants were followed for as long as seven years — 1,198 people stayed cognitively normal, with no memory or thinking problems, during the study. They were compared with 1,218 people who were followed for about the same length of time but who developed dementia.

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Individuals who had developed dementia during the study also developed behavior and mood symptoms such as apathy, appetite changes, irritability, and depression sooner than did people who did not develop dementia.

About 30% of patients who would develop dementia had depression after four years in the study, compared with 15% of those who did not develop dementia.Those who developed dementia were more than twice as likely to develop depression sooner than were those without dementia.