TUESDAY, June 12, 2007 (HealthDay News) -- If you want your mind to stay healthy into your golden years, don't worry, be happy.
That could be the message of new research that shows those prone to worry, anxiety or depression are more likely to develop mild cognitive impairment (MCI), a condition often considered a precursor to the more-debilitating Alzheimer's disease.
"MCI is now recognized as a very early sign of incipient Alzheimer's disease," said Robert S. Wilson, lead author of the study and a neuropsychologist at the Rush Alzheimer's Disease Center in Chicago. "We found that among healthy elderly people without evidence of cognitive dysfunction at the beginning of the study, chronic distress predicted the development of MCI."
"This is consistent with 20 years of literature on the subject," added Dr. Sam Gandy, chairman of the Alzheimer's Association's medical and scientific advisory council and director of the Farber Institute for Neurosciences at Thomas Jefferson University in Philadelphia.
But moving from these findings to knowledge that can really help individuals could be problematic.
"Quantifying stress is like quantifying mental activity," Gandy said. "These are things that are very difficult to standardize and quantify and measure from one human to the next. It's a big challenge to get to something specific."
"The most important implications are down the road," Wilson added.
For now, even stressed people shouldn't get more stressed by the research, another expert advised.
"Fifty percent of individuals who have mild cognitive impairment do not go on to develop dementia," said Dr. Gary J. Kennedy, director of geriatric psychiatry at Montefiore Medical Center in New York City. "It's not what's called a stable, highly reliable diagnosis. People should not be alarmed by the study."
The study findings are published in the June 12 issue of Neurology.
Wilson and his colleagues had hypothesized that distress might play a role in the beginnings of Alzheimer's.
The authors used data from two larger studies -- the Religious Orders Study and the Memory and Aging Project -- to explore the relationship between psychological distress and mild cognitive impairment.
At the beginning of the study, 1,256 participants with no signs of cognitive impairment completed a test designed to assess how prone they were to distress and negative emotions. They were asked their degree of agreement with such statements as "I am not a worrier," "I often feel tense and jittery," and "I often get angry at the way people treat me."
Participants were further evaluated every year for 12 years.
During that time, 482 people -- 38 percent -- developed mild cognitive impairment.
Those who most often experienced negative emotions were more than 40 percent more likely to develop mild cognitive impairment than those who were least prone to these emotions. This suggests that chronic psychological distress is a risk factor for mild cognitive impairment, the researchers said.
And the findings were independent of depression. "We do think depression is somehow associated with an increased risk of dementia, but this [study] controlled for depression," Kennedy said.
It's unclear why this might be the case.
"If this is a vulnerability factor for developing Alzheimer's, the big question is how is it working, what's the neurobiology connecting this," Wilson said. "If we could understand the mechanism, it could open up new avenues for preventing or at least delaying the onset of symptoms."
And scientists may have the answer one day. According to Wilson, all participants in the study have agreed to donate their brains for autopsy after they die.
The Alzheimer's Association has more on mild cognitive impairment.