Summary: A new study provides more evidence that depression may be a risk factor for Alzheimer’s.
People with dementia often report they suffered from depression before they developed serious problems with memory and thinking. Study after study has shown a link between depression and memory loss. Researchers continue to debate whether depression increases the risk of developing serious memory loss or is simply a sign of brain changes underlying Alzheimer’s or other dementias.
Dr. Robert Wilson, Professor of Neurological Sciences and Psychology at Rush University Medical Center, studies the neurobiology of the connection between depression and dementia. In an article in a recent issue of the Archives of General Psychiatry, he and his colleagues provide more evidence that depression may be a risk factor for Alzheimer’s.
The scientists looked at the medical histories of over 900 older Catholic priests, nuns and monks to see whether those who developed Alzheimer’s had increased symptoms of depression shortly before the onset of their dementia. They found no increase, on average, in symptoms of depression before or after a diagnosis of Alzheimer’s in the 190 study participants who did develop the disease.
Although it would be understandable for someone to be depressed because of memory loss, the results of this study suggest that neither the diagnosis of memory loss nor the experience of memory loss necessarily causes depression.
Evidence that depression is a risk factor for memory loss is actually good news, because there are things you can do to reduce depression and thereby reduce your risk of memory loss.
“We are examining the brains of individuals from the Religous Orders Study who had different levels of depression (and other negative emotions) in the last years of life,” Dr. Wilson explains. “We are looking for changes that have been identified in parts of the limbic system (a part of the brain that regulates emotions and memory) of animals subjected to chronic stress (for example, changes in the receptors for stress hormones). If these changes also occur in humans, they could explain why depression is associated with loss of cognition, and they might suggest novel ways of trying to delay the symptoms of dementia. For example, in animals, stress-related damage to the brain is reduced by a number of things including antidepressants, exercise, and certain dietary changes.”
Unlike many Alzheimer’s researchers, Dr. Wilson isn’t really focused on plaques and tangles. “An exciting development in Alzheimer’s research has been that a number of lifestyle and personality factors appear to affect the risk of developing dementia but do not seem to be related to the pathologic lesions in the brain that we traditionally associate with Alzheimer’s and other forms of dementia,” he says.
Dr. Wilson currently has a grant from the U.S. National Institute on Aging for this work. Along with other researchers, he worries about future funding. “Understanding how these risk factors are working is going to be very important if we are going to make progress in disease prevention,” he says. “How quickly this happens will depend on how much the government supports this research. I would encourage concerned families to lobby their elected officials about federal funding of dementia research.”