People who have a tendency to worry or feel very stressed out may be more likely to develop Alzheimer's disease later in life, new research reports.
The relationship between stress and Alzheimer's disease also appears to be much stronger in whites than in African-Americans, the authors note in the journal Neurology.
The nature of the connection between a tendency to worry and the memory-robbing disease is still unclear, study author Dr. Robert S. Wilson of Rush University Medical Center in Chicago told Reuters Health.
However, he said that he suspects that chronic elevations of stress hormones may damage regions of the brain that regulate both behavior under stress and memory.
Wilson emphasized that this study only connects stress and Alzheimer's, and does not prove that one causes the other. The report "does not establish that distress causes dementia," Wilson noted.
But while it's too soon to recommend that people reduce their stress to help avoid Alzheimer's disease, there are many other healthy reasons to relax, he added.
"The tendency to experience psychological distress is a trait that we all have to greater or lesser degrees," Wilson noted. "Family or friends concerned about a loved one who is chronically unhappy should encourage the person to see a qualified mental health professional."
As part of the study, Wilson and his colleagues asked 1,064 white and black people at least 65 years old about their tendency toward worry and stress, then examined them 3 to 6 years later to determine if they had developed Alzheimer's disease.
They found that people who appeared prone to feeling distressed were more than twice as likely to develop Alzheimer's disease within 3 to 6 years. The relationship between stress and Alzheimer's disease was much stronger in white participants, Wilson and his team report.
Wilson added that this is the first study to examine the link between stress and Alzheimer's disease in African-Americans.
"At this point we do not have an explanation for the racial difference, but we think the finding underscores the importance of including racial and ethnic minorities in this kind of research," he noted.