May 21, 2003
The fear and anxiety that accompanies a diagnosis of Alzheimer's disease can understandably cause patients to become depressed, but a new study reports that suffering from depression even years earlier may be a harbinger of the memory-ravaging illness. The study, from researchers at the Boston University School of Medicine, appeared in the May 2003 issue of the Archives of Neurology, a medical journal.
Nobody is sure exactly what causes Alzheimer's, though researchers have identified several risk factors that may increase your chances of developing the disease. Rick factors include advancing age (the older you are, the more likely you are to develop Alzheimer's), a family history (some forms of the disease run in families), low levels of schooling and a head injury earlier in life. In addition, many people who develop Alzheimer's have bouts of depression around the time their illness is diagnosed, or as their symptoms progress. This study, which took into account these previously identified risk factors, adds to a growing body of evidence that a pattern of depression, even decades earlier, may up the risk for developing Alzheimer's.
The trial, called the Mirage Study (Multi-Institutional Research in Alzheimer's Genetic Epidemiology Study), examined nearly 2,000 people with Alzheimer's diseases, and a matching number of their unaffected relatives. Alzheimer's was most likely to develop in those men and women who had symptoms of depression within one year of the onset of the disease. But, those who exhibited symptoms of depression several years earlier were also at increased risk of developing Alzheimer's. Even those who had symptoms of depression 25 years earlier had a slightly increased risk for Alzheimer's.
The findings are consistent with results from an earlier trial, reported in the August 13, 2002 issue of the medical journal Neurology, in which researchers gave yearly neurologic and memory exams to more than 650 nuns and priests aged 65 and older for seven years. Those participants who had the greatest number of symptoms of depression at the start of the study were more likely to develop Alzheimer's disease as the study progressed. And of those who did develop Alzheimer's, those who were also depressed had a more rapid downhill course. That trial was part of the ongoing Religious Orders Study, in which researchers have been evaluating memory skills and the onset of Alzheimer's in members of a religious order over the course of many years.
Researchers speculate that in some people, Alzheimer's could be a long process that begins many years before the actual onset of memory loss, showing up as symptoms of depression, or that depression may in some way prove "toxic" to the brain. Still, more research is needed to unravel the possible link between depression and Alzheimer's. In the current Boston University study, about 14 percent of those who developed Alzheimer's had a history of depression going back some 25 years, according to surveys of family members. In comparison, 7 percent of those who had been depressed long term remained free of the disease. Being depressed or depression-free in your younger years, therefore, is by no means a guarantee that you will or will not develop Alzheimer's in old age. A propensity for depression is likely only one of many still poorly understood factors that may influence whether you later develop Alzheimer's.
Anyone with symptoms of depression should seek medical help for their condition, whether they have Alzheimer's disease or not. Symptoms of depression include:
- Feeling sad, apathetic, or hopeless for weeks to months on end.
- Loss of interest in daily activities, especially ones that used to bring pleasure.
- Poor appetite and weight loss; or increased appetite and excessive weight gain.
- Troubled sleep, waking up repeatedly during the night, or an increased need for sleep.
- Feeling anxious or agitated.
- Trouble thinking or an inability to concentrate.
- Focusing on non-serious physical complaints.
If you experience one or more of these symptoms, or other unusual changes in mood or behavior, consult your physician. Medications and therapeutic counseling are available that can provide relief.
By Toby Bilanow, Medical Writer, for www.ALZinfo.org, The Alzheimer's Information Site.
Reviewed by Samuel E. Gandy, M.D., Ph.D., Chairman of the Scientific Advisory Board, Fisher Center for Alzheimer's Research Foundation.