Low Mood Linked to Alzheimer's
Study finds those who have blue moods more often are more likely to develop disease
MONDAY, Aug. 12, 2002 (HealthDayNews) -- The presence and severity of blue moods may help predict those who will be vulnerable to Alzheimer's disease as they age.
That's the finding of a new study of Catholic clergy, reported in tomorrow's issue of Neurology. Every additional depressive symptom raised the risk of Alzheimer's over the next seven years by almost 20 percent. Nuns, brothers and priests with more mood problems were also more likely to have the steepest drops in mental functioning with age.
An estimated 4 million Americans suffer from Alzheimer's, according to the Alzheimer's Association. That number is projected to soar as the population ages.
More than 19 million adults in this country have some form of depression, according to the National Mental Health Association. Of those, nearly 10 million, or about 5 percent, of people 18 and older have a major depressive disorder.
Previous research has suggested a link between depression and Alzheimer's disease. However, it hasn't been clear if mood problems promote dementia or if they are simply early signs of a fading mind.
In the latest study, Robert Wilson, of the Rush Alzheimer's Disease Center in Chicago, and his colleagues looked for a link between depression and dementia in 651 men and women participating in the Religious Orders Study. None had clinically significant cognitive problems at the beginning of the seven-year project.
Smith's group evaluated the volunteers for signs of emotional distress. Slightly more than half of the clergy, who were at least 65 years old when they started the study, reported no depression at the first interview.
The rest had varying degrees of depressive symptoms -- such as low mood or lethargy -- on a scale of zero to eight. Between 7 percent and 8 percent had a score of four or more, about 7 percent had a three, 10 percent had a two and 24 percent had a one. Only 1 percent of people in the study had symptoms of major depression.
Seven years later, 108 of the subjects had developed apparent Alzheimer's, which can only be confirmed by an autopsy.
Each point on the mood scale boosted the risk of Alzheimer's disease by 19 percent, the researchers found. It also raised their rate of cognitive loss by 24 percent.
"It's not that you just started lower. People are actually declining faster," says Dr. David A. Bennett, director of the Rush Alzheimer's Disease Center and a co-author of the study.
That suggests the blues aren't merely the first notes of Alzheimer's, but that they may somehow aggravate the risk of the disease, Bennett says.
So, too, does the fact that the association between depressive symptoms and dementia held even when the researchers excluded people with the worst scores on the initial cognitive tests.
Bennett's group is now in the process of analyzing brain samples of some of the participants who've already died, including those with Alzheimer's. This pathology evidence should help them draw firmer conclusions about the connection between depression and the disease.
"Whether or not depressive symptoms are a true risk [for Alzheimer's], so that you could intervene and reduce the risk of dementia, or whether it's an early sign, is kind of a big issue," Bennett says. "Our next series of studies is going to try to separate that."
William Thies, vice president of medical and scientific affairs for the Alzheimer's Association, agrees that "the really critical question is whether depression is due to some sort of interaction with the Alzheimer's, or is it simply the depression that's based on decreased [mental] abilities" tied to dementia. "I think that's still an open question," he adds.
However, Thies says doctors who treat people with Alzheimer's should pay attention to signs of mood problems.
"If it's something that's treatable, they may function better if their depression is treated," he says.
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