I worry a lot about anxiety. And for good reason. Anxiety disorders are among the most common mental health woes, and they disproportionately afflict women. And increasingly, anxiety is becoming associated with all sorts of negative longer-term consequences, from greater disability among older patients and impaired cognition to higher health care costs.
A recent study of Swedish twins adds to this growing body of research: In analyzing 28 years of data from the Swedish Adoption Twin Study of Aging, researchers from the University of Southern California report that “anxiety symptoms were associated with increased risk of dementia.”
Specifically, the researchers found a “48% increased risk of becoming demented for those who had experienced high anxiety at any time compared with those who had not.”
And when the researchers compared twins, they found that among the pairs in which one twin developed dementia and the other did not: “31.6% of the time, the twin with lower anxiety was the twin who became demented, whereas, 68.4% of the time, the twin with higher anxiety was the twin who became demented. Relatively speaking then, it was about twice as risky to be the twin with the higher anxiety,” said Margaret Gatz, professor of psychology, gerontology and preventive medicine at USC and one of the study authors.
The analysis, published in the journal Alzheimer’s & Dementia, included 1,082 participants who completed questionnaires and in-person tests and underwent screening for dementia beginning in 1984 and throughout the study.
I asked the study’s first author, Andrew J. Petkus, Ph.D., in the psychology department at USC, about the findings. Here, lightly edited, is his email response:
What’s the most surprising finding in this analysis?
Anxiety was found to be associated with higher risk of dementia independent of depression. Although anxiety is the most common mental health problem in later life, it has been given comparatively less research attention than depression. Depression has been well established as a prospective risk factor for dementia. Anxiety and depression typically occur together and most of the work examining depression and dementia does not account for anxiety. Most studies that have found depression to be a risk factor for cognitive decline did not control for anxiety and therefore it is possible that they may be really picking up on anxiety instead of depression.
In addition, our twin analyses — examining cases where one twin developed dementia while the other one doesn’t — higher anxiety was still a significant predictor of dementia. In these analyses the twin who reported more anxiety was almost twice as likely to develop dementia. The twin analyses also suggest that one reason anxiety may be a risk factor in dementia is genetic factors in common to anxiety and dementia. Continue reading