Emerging research suggests depression and behavioral changes may occur before memory declines in people who will go on to develop Alzheimer’s disease.
Researchers at Washington University School of Medicine said while it has been known that many people with Alzheimer’s experience depression, irritability, apathy, and appetite loss, experts did not recognize how early these symptoms appear.
Pinpointing the origins of these symptoms could be important to fully understanding Alzheimer’s effects on the brain and finding ways to counteract them.
“There has been conflicting evidence on the relationship between Alzheimer’s and depression,” said senior author Catherine M. Roe, Ph.D., assistant professor of neurology.
“We still don’t know whether some of these symptoms, such as irritability and sadness, are due to people realizing on some level that they are having problems with memory and thinking, or whether these symptoms are caused directly by Alzheimer’s effects on the brain.”
The study has been published in the journal Neurology.
Roe and colleagues analyzed data on 2,416 people ages 50 and older. Study participants were evaluated on how they performed in extensive tests of mental function and psychological health for up to seven years.
All of the participants were cognitively normal at the start, but over the course of the study, 1,218 of them developed dementia.
Those who developed dementia during the study were more likely to have mood and behavioral changes first. For example, four years into the study, 30 percent of those who would go on to develop dementia had developed depression.
In comparison, after the same period of time, only 15 percent of those who did not develop dementia during the study had become depressed. In addition, those who would go on to develop dementia were more than 12 times as likely to have delusions as those who did not develop dementia.
Alzheimer’s researchers have been working to develop markers they can use to diagnose disease before the onset of dementia. The hope is to begin treating the condition before patients develop dementia.
However, Roe cautioned that additional knowledge on how markers connect to the disease.