Depression and other behavior changes may show up in people who will later develop Alzheimer's disease even before they start having memory problems, according to a new study published in Neurology®, the medical journal of the American Academy of Neurology.
"While earlier studies have shown that an estimated 90 percent of people with Alzheimer's 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 Washington University School of Medicine in St. Louis, Mo., and a member of the American Academy of Neurology.
The study looked at 2,416 people age 50 and older who had no cognitive problems at their first visit to one of 34 Alzheimer's disease centers across the country. The participants were followed for up to seven years. Of the participants, 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.
The people who developed dementia during the study also developed behavior and mood symptoms such as apathy, appetite changes, irritability and depression sooner than the people who did not develop dementia. For example, 30 percent of people who would develop dementia had depression after 4 years in the study, compared to 15 percent of those who did not develop dementia. Those who developed dementia were more than twice as likely to develop depression sooner than those without dementia and more than 12 times more likely to develop delusions than those without dementia.
Roe said the study adds to the conflicting evidence on depression and dementia. "We still don't know whether depression is a response to the psychological process of Alzheimer's disease or a result of the same underlying changes in the brain," she said. "More research is needed to identify the relationship between these two conditions."