Adults who frequently feel negative emotions such as depression and anxiety may be twice as likely to develop Alzheimer’s disease as adults who are least likely to experience such distress, according to an article in the December 9th issue of Neurology.

The current work was part of a larger American study on aging involving older men and women within a large religious community (Roman Catholic nuns, priests, and brothers). Researchers tested 797 people (average age, 75 years) at baseline and then on an annual basis. Participants were evaluated on their level of vulnerability to stress with a rating scale that has been proven validity. Participants rated their level of agreement (strongly disagree, disagree, etc.) with statements such as “I am not a worrier,” “I often feel tense and jittery,” and “I often get angry at the way people treat me.”

“People differ in their tendency to experience psychological distress, and this is a stable personality trait throughout adulthood,” said lead author Robert S. Wilson, PhD. “Since chronic stress has been associated with changes in the hippocampal area of the brain and problems with learning and memory, we wanted to test the theory that psychological distress may affect the risk of developing Alzheimer’s disease.”

Wilson said the findings are important because evidence has shown that many of the adverse effects of stress on the brain can be blocked by drugs, including antidepressants. “But much more research is needed before we can determine whether the use of antidepressants could help reduce the risk of Alzheimer’s disease,” he said.

During an average of 4.9 years follow-up, 140 people in the study developed Alzheimer’s disease. People in the 90th percentile for distressing emotions were twice as likely to develop Alzheimer’s disease as those in the 10th percentile.
Proneness to stress was related to decline in episodic memory, which was tested by asking participants to recall a list of words or a story. Problems with episodic memory are typical in people with Alzheimer’s disease. Episodic memory ability declined 10 times faster in those evaluated as high in distress than in people low in distress.

The researchers also evaluated participants on their level of symptoms of depression. Because symptoms of depression are manifestations of psychological distress, the researchers analyzed the test data while controlling for symptoms of depression, but the results were not changed.

The researchers also measured participants’ level of cognitive activity by asking them how often they did stimulating activities such as reading a book. To see whether cognitive activity could account for the relationship between distress and Alzheimer’s disease, the researchers analyzed the data while controlling for cognitive activity, but the results were not changed.

To investigate whether proneness to distress was an early sign of Alzheimer’s disease rather than a risk factor, the researchers studied the brains of 141 participants who died during the course of the study. Of those, 57 met the criteria for probable Alzheimer’s disease. The researchers found that vulnerability to distress was not related to measures of Alzheimer’s disease pathology such as plaques and tangles in the brain.

“This result suggests that stress proneness is a co-factor leading to dementia in Alzheimer’s disease, but these results need to be confirmed,” said John C.S. Breitner, MD, MPH, who wrote an editorial accompanying the study.