Young adults who battle life's stresses, but not very successfully, or who have a hostile attitude go on to have cognitive deficits in middle-age, a new study suggests.
The value of this study, and similar ones, is that they raise awareness of the importance of interacting with "a whole human being," said lead author Lenore J. Launer, PhD, senior investigator, Laboratory of Epidemiology and Population Sciences, National Institute on Aging, Bethesda, Maryland.
"There are many aspects to a patient, including personality, that in one way or another contribute to whatever brings them to the doctor," she said. "It's important to get to know the patient, and, if it seems like that patient is under stress, then action should be taken."
The results were published online March 2 in Neurology.
The analysis included 3126 participants from the Coronary Artery Risk Development In Young Adults (CARDIA) study. CARDIA is a large, prospective, population-based cohort of white and black women and men followed since 1985–1986.
At baseline, when the participants were an average of 25 years old, researchers used the John Henryism Scale for Active Coping to measure effortful coping. Someone with a high score on this scale, which ranges from 12 to 60, would be trying hard to deal with whatever life throws at them but not handling barriers to success very well.
"It's when someone tries over and over again to do their best, and it just doesn't work out for them," explained Dr Launer. "The end bad result is getting sort of burnt out because, at the end of the day, they just don't seem to be able to make headway in the things they're interested in doing."
Investigators used the Cook-Medley scale to assess hostility. This scale, which ranges from 0 to 50, measures hostility and suspicious attitudes towards others. An example of a true-or-false question included in the questionnaire: "When someone does me wrong, I feel I should pay him back if I can just because of the principle of the thing."
For both hostility and effortful coping, researchers separated participants into categories of low, mid-low, mid-high, and high.
When participants were an average age of 27 years (year 2 of the study), researchers measured their cognitive ability using the mirror-tracing star test. This involves drawing a star diagram within a narrow boundary while looking at your hand in a mirror and with your direct view being blocked. The test assesses working memory, attention, psychomotor speed, concentration, and executive function.
In 2010–2011, when participants were on average 50 years old, they underwent a battery of cognitive tests that included the Rey Auditory Verbal Learning Test (RAVLT) for memory, the Digit Symbol Substitution Test (DSST) for psychomotor speed, and the modified Stroop Test for executive function. From these, investigators developed a composite cognitive score.
The study showed that compared to those with the lowest level, participants with the highest effortful coping at baseline had lower cognitive function in midlife (0.30 standard deviation [SD] units lower; 95% confidence interval [CI], –0.48 to –0.12), after adjustment for sociodemographic characteristics, negative life events, and cumulative exposure to cardiovascular risk factors (CVRF), depressive symptoms, feeling discriminated against, and cognitive ability at baseline.
As for hostility, the study found that the highest level at baseline was also associated with lower cognitive function in midlife, independent of demographic characteristics, educational level, and depression and that these levels were not confounded by lifelong depression and feeling discriminated against (0.21 SD lower vs lowest level; 95% CI, –0.39 to –0.02).
However, after additional adjustment for negative life events, midlife smoking and alcohol habits, and lifelong exposure to CVRFs, the difference in composite score between those with the highest and those with the lowest hostility level was only borderline statistically significant (–0.18; 95% CI, –0.37 to 0.01).
Researchers noted differences in performance on individual cognitive tests according to psychological characteristics. On average, those in the highest vs the lowest quartiles of hostility recalled 0.16 fewer words (RAVLT; P < .05), substituted correctly 1.88 fewer symbols (DSST; P < .05), and had a 0.57 higher interference score (Stroop test; P < .07). The corresponding measures (same P values) for effortful coping were 0.30 fewer words recalled, 2.33 fewer symbols substituted correctly, and a 0.38 higher interference score.
The "underlying hypothesis" is that both hostility and effortful coping lead to stress, which in turn could cause cardiovascular disease (eg, hypertension) but could also work directly on the brain, said Dr Launer. "So in that context, these personality traits could be said to increase the risk for cognitive impairment."
But it's important to remember that this is a cross-sectional study, and the cognitive battery was administered only in midlife, not in early adulthood, said Dr Launer. "It's possible that the people who had the highest level of hostility and effortful coping always had lower cognitive function."
The lack of cognitive battery at age 25 is a "major weakness" of the study, according to Richard B. Lipton, MD, professor and vice chair, neurology, professor, psychiatry and behavioral science, and director, Division of Cognitive Aging and Dementia, Albert Einstein College of Medicine, Bronx, New York.
"As a consequence, we don't know if cognitive differences were present at baseline or developed in relation to hostility or effortful coping over the 25 years of follow-up," said Dr Lipton, who is also a member of the American Academy of Neurology.
However, he added that based on the earlier cognitive measure, "it appears that cognitive differences were not present at baseline; rather, they appear to have accumulated in the groups with high effortful coping and hostility."
Another possible study limitation was that those included in the analysis had lower levels of both hostility and effortful coping compared with those who were excluded. This may have led to an underestimation of the true effect in the analysis.
How young adults might better manage stress "is the million-dollar question," said Dr Launer. But if neurologists notice that a patient is under a lot of stress, "they should have something in their files, such as a yoga program, to refer that patient to," she said.
"I think neurologists have to know a little bit more beyond what they're immediately dealing with, in order to really improve health care."
Indeed, the results "raise the possibility that behavioral interventions designed to reduce hostility and improve effortful coping could reduce the risk of cognitive decline," added Dr Lipton.
He noted that the influence of personality traits and coping style on cognitive performance has primarily been examined in patients over age 65. One study he cited found that high levels of perceived stress in older adults predicted the onset of amnestic mild cognitive impairment, an early manifestation of Alzheimer's disease.
"In older adults, personality, coping style and perceived stress may accelerate the development of age-related pathologies such as Alzheimer's disease. In midlife, these pathological processes are very rare. Studies in young and midlife adults are helpful to assess the influence of personality and coping style on cognitive performance in the absence of neurodegenerative disease."
In the current study, the association between high levels of effortful coping at age 25 and reduced cognitive performance at age 50 persisted after adjustment for all relevant variables, but the effect of high hostility levels, while also associated with reduced cognitive performance, seemed to be related, at least in part, to cardiovascular risk factors, commented Dr Lipton.
Controlling for such risk factors as well as for demographic features, depression, negative life events, smoking, and alcohol was one of the strengths of the study, he said. Other strengths included its large sample size, the 25-year follow-up, and use of a robust cognitive battery, he added.
The Coronary Artery Risk Development in Young Adults Study (CARDIA) is conducted and supported by the National Heart, Lung, and Blood Institute (NHLBI) in collaboration with the University of Alabama at Birmingham, Northwestern University, University of Minnesota, Kaiser Foundation Research Institute, and Johns Hopkins University School of Medicine. CARDIA is also partially supported by the Intramural Research Program of the National Institute on Aging (NIA) and an intra-agency agreement between NIA and NHLBI. Dr Launer nd Dr Lipton have disclosed no relevant financial relationships.
Neurology. Published online March 2, 2016. Abstract
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Cite this: Hostility, Stress Levels Linked to Cognitive Deficits - Medscape - Mar 02, 2016.