Psychological Factors May
Raise Alzheimer's Risk

Susceptibility to psychological distress seems to be associated with the risk of Alzheimer's disease, researchers in Chicago report in the current issue of the journal Neurology.

Because chronic stressful experience is linked to structural changes in the brain and with impaired learning and memory, Dr. Robert S. Wilson and colleagues at Rush-Presbyterian-St. Luke's Medical Center hypothesized that a propensity to experience psychological distress is related to the risk of Alzheimer's disease.

To investigate, they analyzed data from the Religious Orders Study, which included 797 individuals, average age 75 years, who were free of dementia at the start of the trial. The subjects underwent complete neurologic examinations and completed a test for signs of neurosis. At annual follow-ups, the subjects also underwent a battery of 19 tests that measured mental functioning.

During an average follow-up of about five years, 140 individuals were diagnosed with Alzheimer's disease.

After adjusting the findings for age, sex, and education, Wilson's team found that each one-point increase in test score for distress-proneness was associated with a six percent increased risk of Alzheimer's disease and a seven percent decline in mental capacity. Compared with people with the lowest scores, the risk was approximately doubled in persons with the highest scores.

Episodic memory, which the investigators note is primarily mediated by formation of the hippocampus, was more affected by symptoms of neurosis than were other mental functioning systems, such as word memory, and visual and spatial ability.

The authors were surprised to see that this trait was not associated with the extent of plaques and neurofibrillary tangles in the brain, which reflects severity of Alzheimer's disease. They suggest that the association between chronic psychological distress and Alzheimer's disease "probably reflects neurobiologic mechanisms other than the pathologic hallmarks of Alzheimer's disease."

Wilson notes in a journal press release that antidepressants and other drugs may block the adverse effects of stress. "But much more research is needed before we can determine whether the use of antidepressants could help reduce the risk of Alzheimer's disease."

Regardless of whether higher scores on symptoms of neurosis are related to or are early signs of Alzheimer's disease dementia, this study demonstrates that distress-proneness predicts an increased risk of Alzheimer's disease in an elderly population, Dr. John C. S. Breitner, with the University of Washington in Seattle, and Dr. Paul T. Costa, with the National Institute on Aging in Baltimore, remark in a related editorial.

SOURCE: Neurology, December 9, 2003.

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