It is estimated that 4.5 million Americans have Alzheimer’s disease (AD). Alzheimer’s disease is the most common form of dementia , which affects a person’s memory, reasoning skills, judgment, and behavior.

What causes Alzheimer’s disease? Researchers don’t know for sure. But it is thought that a combination of factors increases the risk of AD, and this combination varies from individual to individual. Age is the most significant risk factor, but family history, blood pressure, cholesterol levels, and diet may also play a part.

New research is investigating how risk factors can be modified to protect against AD. For example, mental, physical, and social activities may play a protective role, while stress is likely to have a detrimental effect. It is interesting to note that chronic psychological distress has been associated with structural changes in an area of the brain involved in learning and memory.

A new study in the December (1 of 2) 2003 issue of Neurology looked at the effects of psychological distress on the risk of developing Alzheimer’s disease. The researchers found that people who were the most prone to distress were twice as likely to develop AD as compared to people who were the least prone.

About the Study

This study used data from the Religious Orders Study, an investigation of Alzheimer’s disease in older Catholic nuns, priests, and brothers. The participants took part in annual exams and agreed to donate their brain to the study when they died. There were 864 people eligible for this study, with an average age of 75.

Before the study began, the participants filled out questionnaires to assess their level of agreement (strongly disagree, disagree, neutral, agree, strongly agree) with a set of statements designed to assess psychological distress (i.e., “I am not a worrier,” “I often feel tense and jittery,” “I often get angry at the way people treat me”).

On average, the participants were followed for five years, during which they took part in annual clinical exams. The exams included complete neurologic assessments and detailed cognitive function testing, which included, among other things, evaluation of memory. The participants also reported their level of intellectual engagement, which is protective from AD, and depression , which may be associated with AD risk.

One concern of the researchers was that susceptibility to psychological distress may actually be a sign of existing AD, rather than a risk factor. To evaluate this possibility, the researchers examined the brains of 141 participants who died during the study to find out if those who were vulnerable to distress, but did not show signs of AD during life, had pathologic evidence of the disease in their brains.

The Findings

During the course of the study, 140 people developed Alzheimer’s disease, and their susceptibility to psychological distress was a significant predictor. Specifically, people who scored in the 90th percentile for proneness to distress were twice as likely to develop AD as people who scored in the 10th percentile.

Neither intellectual engagement nor depression affected the link between proneness to distress and AD. The autopsies also did not suggest that vulnerability to stress is a sign of AD.

How Does This Affect You?

These findings suggest that a person’s susceptibility to negative emotions (i.e., depression, anxiety ) in response to a stressful situation probably does affect their risk of developing Alzheimer’s disease. This would be consistent with a growing body of evidence supporting a link between psychological stress and chronic disease.

However, despite the autopsy results, the study was not long enough to determine whether this susceptibility was truly a risk factor for AD or just an early sign. A study that assessed people’s emotional vulnerability in midlife and followed them into their later years to see if they developed AD would be needed to make this determination.

At this time, it is not known whether a person who is prone to psychological distress can modify this response enough to lower their risk of AD or any other conditions. While certain psychological interventions, like cognitive-behavioral therapy, have been shown to ameliorate the stress response, there is currently no evidence that it can prevent or delay the onset of AD.

Emerging research, however, has indicated that the changes in the brain associated with chronic stress can be blocked by a variety of medications, including antidepressants. It may one day be possible to use these medication to prevent or treat AD in vulnerable individuals. That day cannot come soon enough.