Depression and other behaviour changes set in before memory problems show up, in people who later develop Alzheimer's disease, reveals a new study published in the January 14, 2015, online issue of 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."
The study was supported by the Longer Life Foundation, National Institute on Aging, Fred Simmons and Olga Mohan and the Washington University Knight Alzheimer's Disease Research Center.
The American Academy of Neurology, an association of more than 28,000 neurologists and neuroscience professionals, is dedicated to promoting the highest quality patient-centered neurologic care. A neurologist is a doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system such as Alzheimer's disease, stroke, migraine, multiple sclerosis, brain injury, Parkinson's disease and epilepsy.