Research on depression and cognitive health
In the study, published in January in the journal Neurology, the researchers from the Washington University School of Medicine in St. Louis looked at data from 2,416 cognitively normal patients, each of whom entered the study over the age of 50.
The data followed these patients for seven years with scientists interviewing and testing patients on their psychological state of being and their cognitive health. Examining the data at the conclusion of seven years, the researchers found that 1,218 of the 2,416 had developed some form of dementia.
They also found that those who developed dementia were twice as likely to have developed depression before any of the common symptoms of dementia had begun. Further, those who went on to develop Alzheimer’s or another form of dementia were 12 times more likely to develop delusions.
Alzheimer’s and depression: conflicting evidence
While researchers noted that developing depression and anxiety once Alzheimer’s or dementia has set in is more often the case, it was not known if depression could be a precursor to those illnesses, which the test results seem to suggest they can be. They caution, however, that they cannot say if cognitive impairment causes depression before signs of the impairment actually occur.
The senior author of the study, Dr. Catherine Roe, an assistant professor of neurology at the university, said there are still questions to be asked about the relationship between cognitive impairment and depression. There is the hope that understanding the relationship more fully may lead to early intervention but, she said, there is work yet to be done.
“There has been conflicting evidence on the relationship between Alzheimer’s and depression,” Dr. Roe said in a statement. “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.”
