A new research has said that depression and behavioral changes may precede the memory declines in people who later develop Alzheimer's disease.
Researchers have known that many people with Alzheimer's experience depression, irritability, apathy and appetite loss but had not recognized 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.
According to senior author Catherine M. Roe, PhD at Washington University School of Medicine in St. Louis, there has been conflicting evidence on the relationship between Alzheimer's and depression, But they still didn't know whether some of these symptoms were due to people realizing on some level that they are having problems with memory and thinking, or were caused directly by Alzheimer's effects on the brain.
Roe and her colleagues analyzed data on 2,416 people ages 50 and older. Scientists regularly evaluated the participants for up to seven years, including how they performed in extensive tests of mental function and psychological health.
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, 4 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 than 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.
The study is published in Neurology.