June 11, 2007 -- People who often feel negative emotions may be more likely to develop memory problems as they age, according to a new study.
The researchers included Robert S. Wilson, PhD, who is the senior neuropsychologist at the Rush Alzheimer's Disease Center at Chicago's Rush University.
Wilson's team pooled data from two studies on aging. One study featured Catholic nuns, priests, and brothers from across the U.S. The other study included older adults in Chicago.
Together, the studies included 1,256 people who were nearly 77 years old, on average.
When the studies started, none of the participants had memory problems or dementia. They completed surveys about their negative emotions.
Every year for up to 12 years, participants got medical checkups and took mental skills tests.
During that time, 482 participants -- 38% -- developed mild cognitive impairment, which is marked by memory problems that aren't severe enough for dementia diagnosis.
People who were prone to psychological distress (negative emotions) were more likely to develop mild cognitive impairment than their more upbeat peers.
Those with the highest degree of psychological distress were about 42% more likely to develop mild cognitive impairment than those with the lowest level of psychological distress.
The results held when the researchers considered participants' depression and age. The pattern was somewhat stronger in men than women; the reason for that finding isn't clear.
Participants only completed the survey about their negative emotions once, when the studies started. So it's not clear if they suffered more (or less) psychological distress over time.
However, people's basic tendency toward negative emotions doesn't shift drastically over time, the researchers note. So Wilson's team assumed that participants maintained basically the same amount of psychological distress throughout the follow-up period.
"People differ in how they tend to experience and deal with negative emotions and psychological distress, and the way people respond tends to stay the same throughout their adult lives," Wilson says in an American Academy of Neurology news release.
"These findings suggest that, over a lifetime, chronic experience of stress affects the area of the brain that governs stress response. Unfortunately, that part of the brain also regulates memory," says Wilson.
The study appears in the journal Neurology's June 12 edition.