Depression in the elderly increases the risk of subsequent mental impairment and can act as a predictor of future intellectual decline, University of Rochester Medical Center psychiatrists and researchers have found.
"We can't conclude that treatment or prevention of depression would reduce or prevent cognitive decline but these findings certainly raise the possibility and that would be our hope," said Jeffrey M. Lyness, M.D., professor of psychiatry, associate chair for education in the Department of Psychiatry and senior author of an article on the research.
This is the first study to analyze simultaneously the roles of depression and intellectual dysfunction over time in a large group of older people. The researchers followed more than 700 patients over two years for the study that was published in The American Journal of Psychiatry.
The researchers looked at loss of so-called executive functions that involve high-level mental processes, such a making decisions, organizing, planning and doing a series of things in sequence.
"You can have a good memory and good language skills but if you lose executive function, you can't do very well in daily life," Lyness said.
Participants, who were 65 years of age and older, were recruited from private practices and University-affiliated clinics in Monroe County, New York. Trained interviewers questioned participants in their homes or in research offices at the Medical Center. They also reviewed each patient's primary care medical chart, recording information about mood and cognitive symptoms, disorders, or treatments as well as active and past medical problems and current medications.
The patient interviews included assessments of cognition, functional status, and depression. Additional interviews and chart reviews were conducted one year after the initial interview and then again two years later. Sophisticated methods of statistical analysis were used to review the results.
"Not every elderly person who is depressed becomes intellectually impaired, but depression raises the risk of executive dysfunction," Lyness said. "We began to see it at the one-year mark and it was clear after two years."
Physicians who treat older patients should be aware of the increased risk of loss of mental functions for depressed patients, the researchers concluded.
"The next step is to study whether treatment or prevention of depression can prevent decline in executive function," Lyness said.
In addition to Lyness, the authors of the article include: Xingjia Cui, M.D., M.P.H., M.S., who was a resident in psychiatry at the Medical Center and now works at the Veterans Affairs Medical Center in Canandaigua; Xin Tu, Ph.D., professor of biostatistics and professor of psychiatry; Deborah A. King, Ph.D., associate professor of psychiatry, and Eric D. Caine, M.D., chair of the Department of Psychiatry. The article was published in the August issue of the journal. A follow-up discussion of the results will appear in an upcoming issue.