It is very important and interesting to read Wilson and his colleagues' research on whether stress or proneness to distress is a risk factor for, or a sign of, cognitive decline. They acknowledged that the latter is possible, but favor the idea that chronic distress is a risk factor because distress does not seem to increase in old age, even in Alzheimer's disease.

In more detail, Wilson et al. (2007) found that people who scored high on a test of chronic mental distress were over 40 percent more likely to develop mild cognitive impairment than those who were the most laid back. In a simple proportional hazards model analysis of the prospective data from two large studies of aging and the brain, the risk of developing mild cognitive impairment over a 12-year follow-up increased by over 2 percent for every one-point increase on a measure of chronic distress. The findings come from 1,256 volunteers with a mean age of 76.8 years. The hazard ratio was 1.02, with a 95 percent confidence interval from 1.01 to 1.04. Nevertheless, depressive symptoms were associated with increased...  Read more

It is very important and interesting to read Wilson and his colleagues' research on whether stress or proneness to distress is a risk factor for, or a sign of, cognitive decline. They acknowledged that the latter is possible, but favor the idea that chronic distress is a risk factor because distress does not seem to increase in old age, even in Alzheimer's disease.

In more detail, Wilson et al. (2007) found that people who scored high on a test of chronic mental distress were over 40 percent more likely to develop mild cognitive impairment than those who were the most laid back. In a simple proportional hazards model analysis of the prospective data from two large studies of aging and the brain, the risk of developing mild cognitive impairment over a 12-year follow-up increased by over 2 percent for every one-point increase on a measure of chronic distress. The findings come from 1,256 volunteers with a mean age of 76.8 years. The hazard ratio was 1.02, with a 95 percent confidence interval from 1.01 to 1.04. Nevertheless, depressive symptoms were associated with increased risk, but the association became non-significant when the researchers controlled for distress score.

It is also important to recognize that depression, although known to predict cognitive impairment and dementia, appeared in the study as well as a few other recent studies (e.g., Caracciolol et al. 2011; Geda et al. 2006) to be merely a "proxy for the enduring tendency to experience negative emotions."

Geda et al. (2006) suggested that mild cognitive impairment, which is considered a transitional step to dementia, implies mild memory or cognitive decline, but no significant disability. Recent research such as the findings of Geda et al. and Wlison et al. (2007) suggest that over a lifetime, chronic stress affects the area of the brain that governs stress response and, unfortunately, that part of the brain also regulates memory.

As suggested by Caracciolo et al. (2011), people are considered to differ in the way they tend to deal with negative emotions and psychological distress, and such coping means or styles tend to remain relatively unchanged throughout their later life. That is possibly why chronic distress may be a risk factor for cognitive or emotional problems in older age.

Moreover, another unexpected, interesting finding of recent research like the study by Wilson et al. is that the association of distress with risk of impairment was higher in men than in women, although the two genders do not differ in the likelihood of experiencing distress. Future research to understand this gender difference on the association between chronic distress and risk of cognitive impairment is recommended.

References:
Caracciolo B, Bäckman L, Monastero R, Winblad B, Fratiglioni L. The symptom of low mood in the prodromal stage of mild cognitive impairment and dementia: a cohort study of a community dwelling elderly population. J Neurol Neurosurg Psychiatry. 2011. Abstract (http://jnnp.bmj.com/content/early/2011/01/05/jnnp.2010.225003.full)

Geda YE, Knopman DS, Mrazek DA, et al. Depression, Apolipoprotein E Genotype, and the Incidence of Mild Cognitive Impairment: A prospective cohort study. Arch Neurol. 2006;63:435-440. Abstract

Wilson RS, Schneider JA, Boyle PA, Arnold SE, Tang Y, Bennett DA. Chronic distress and incidence of mild cognitive impairment. Neurology. 2007, June 12;68:2085-2092. Abstract

View all comments by Wai-Tong Chien