Depression, anxiety, irritability and changes in appetite are among the earliest symptoms of Alzheimer’s disease, and may occur even before serious memory problems become evident, a new study reports. The study adds to a growing body of evidence that Alzheimer’s is a multi-year process and that behavioral and mood changes, along with problems with memory and thinking skills, may begin years before a diagnosis of Alzheimer’s is made.

“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, of Washington University School of Medicine.

The study, published in Neurology, the medical journal of the American Academy of Neurology, looked at 2,416 people age 50 and older who had no cognitive problems at the study’s start. Participants were recruited from 34 Alzheimer’s disease centers across the United States.

The participants were followed for up to seven years. During that time, 1,198 people retained healthy memory and thinking skills. They were compared with 1,218 who developed Alzheimer’s or other forms of dementia.

The researchers found that symptoms of depression were likely to increase with aging, but that they were twice as likely in those later diagnosed with dementia. Thirty percent of people who would develop dementia had depression within the first four years of the study, compared to 15 percent of those who did not develop dementia

Those who went on to develop dementia were also more likely to develop behavioral and mood changes such as apathy, appetite changes and irritability sooner than those who remained dementia-free.

As Alzheimer’s progresses, behavioral problems like agitation, aggression and psychosis typically become more prominent. But this study shows that behavioral changes may occur in the earliest stages of Alzheimer’s.

“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,” Dr. Roe said.  People who are developing memory problems may, understandably, become anxious, agitated or depressed because they feel that their mind is slipping. It is also possible that the same process that kills brain cells in Alzheimer’s disease may also trigger depression and other psychological problems. “More research is needed to identify the relationship between these two conditions,” Dr. Roe said.

By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by William J. Netzer, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.

Source: Mary Clare Masters, MD, John C. Morris, MD, Catherine M. Roe, PhD: “Noncognitive” Symptoms of Early Alzheimer Disease: A Longitudinal Analysis. Neurology Vol. 84, pages 1-6, 2015.