, a new study shows.
Individuals with elevated stress levels also had higher rates of diabetes, hypertension, and other cardiovascular disease (CVD) risk factors. But even after controlling for those risk factors, stress remained an independent predictor of cognitive decline.
The national cohort study showed that the association between stress and cognition was similar between Black and White individuals and that those with controlled stress were less likely to have cognitive impairment than those with uncontrolled or new stress.
“We have known for a while that excess levels of stress can be harmful for the human body and the heart, but we are now adding more evidence that excess levels of stress can be harmful for cognition,” said lead investigator Ambar Kulshreshtha, MD, PhD, associate professor of family and preventive medicine and epidemiology at Emory University, Atlanta. “We were able to see that regardless of race or gender, stress is bad.”
The findings were published online in JAMA Network Open.
Independent risk factor
For the study, investigators analyzed data from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study, a national population-based cohort of Black and White participants aged 45 years or older, sampled from the U.S. population.
Participants completed a questionnaire designed to evaluate stress levels when they were enrolled in the study between 2003 and 2007 and again about 11 years after enrollment.
Of the 24,448 participants (41.6% Black) in the study, 22.9% reported elevated stress levels.
Those with high stress were more likely to be younger, female, Black, smokers, and have a higher body mass index and less likely to have a college degree and to be physically active. They also had a lower family income and were more likely to have cardiovascular disease risk factors, such as hypertension, diabetes, and dyslipidemia.
Participants with elevated levels of perceived stress were 37% more likely to have poor cognition after adjustment for sociodemographic variables, cardiovascular risk factors, and depression (adjusted odds ratio, 1.37; 95% confidence interval, 1.22-1.53).
There was no significant difference between Black and White participants.
Damaging consequences
Researchers also found a dose-response relationship, with the greatest cognitive decline found in people who reported high stress at both time points and those who had new stress at follow up (aOR, 1.16; 95% CI, 0.92-1.45), compared with those with resolved stress (aOR, 1.03; 95% CI, 0.81-1.32) or no stress (aOR, 0.81; 95% CI, 0.68-0.97).
A change in perceived stress by 1 unit was associated with 4% increased risk of cognitive impairment after adjusting for sociodemographic variables, CVD risk factors, lifestyle factors, and depressive symptoms (aOR, 1.04; 95% CI, 1.02-1.06).
Although the study didn’t reveal the mechanisms that might link stress and cognition, it does point to stress as a potentially modifiable risk factor for cognitive decline, Dr. Kulshreshtha said.
“One in three of my patients have had to deal with extra levels of stress and anxiety over the past few years,” said Dr. Kulshreshtha. “We as clinicians are aware that stress can have damaging consequences to the heart and other organs, and when we see patients who have these complaints, especially elderly patients, we should spend some time asking people about their stress and how they are managing it.”