Being agreeable can help with social interaction, according to researchers from the National Institute on Aging and Johns Hopkins University, both in Baltimore, Maryland; and Florida State University College of Medicine in Tallahassee, Florida. The researchers say agreeableness may also lower the risk of Alzheimer disease (AD).
The researchers examined the association between personality traits and risk of AD, using data from 1,671 adults who were followed for up to 22 years in the Baltimore Longitudinal Study of Aging (BLSA), one of the longest running studies in the U.S. The researchers also did a meta-analysis on pooled results from prospective studies involving 5,054 participants.
Participants underwent a series of tests, including a neuropsychological battery, neurologic examination, medication review, and structured interview. They also completed the self-report version of the revised NEO Personality Inventory (NEO-PI-R), a 240-item questionnaire. The NEO-PI-R assesses 5 major dimensions of personality: neuroticism (the tendency to experience negative emotions such as anxiety, anger, and sadness); extraversion (being sociable, assertive, enthusiastic, and energetic); openness (being imaginative, unconventional, curious, and emotionally and artistically sensitive); agreeableness (being altruistic, trusting, and cooperative); and conscientiousness (being organized, strong-willed, persistent, reliable, and a follower of rules and ethical principles). Based on previous research, the researchers expected that people with high conscientiousness (ie, organized and self-disciplined) and low neuroticism (less likely to be anxious, depressed, and vulnerable to stress) would have a lower risk of AD.
Onset of AD was diagnosed in 90 participants within 8 years, on average, from baseline. The researchers found that for each standard deviation (SD) increase in neuroticism, the risk of incident AD increased by > 30%. The risk was 3 times higher for the group in the highest quartile of neuroticism. Moreover, > 10% of the AD cases in the population could be attributed to high neuroticism. The results were similar for conscientiousness. The risk of incident AD was 3 times higher for the lowest quartile, and about 10% of AD cases could be attributed to low conscientiousness. The results remained the same when the researchers excluded people aged < 50 years at baseline or those who developed AD within 2 years of the baseline personality assessment.
Among the neurotic tendencies, anxiety, anger, hostility, and depression increased the risk of AD by > 30%. On the conscientiousness scale, self-discipline had the strongest association, followed by competence, order, and dutifulness. Risk of AD was reduced by > 30% for each SD higher score on any of those facets.
The researchers say low conscientiousness and high neuroticism are also related to inflammatory markers such as interleukin 6 and C-reactive protein. But neuroticism could also be a signifier for a variety of lifestyle behaviors that have been separately linked to AD. For instance, low conscientiousness and high neuroticism are associated with cigarette smoking, physical inactivity, obesity, and depression—all risk factors for dementia.
Personality traits are also related to coping skills, the researchers note. Chronic stress throughout the lifespan may contribute to the inability to cope with the neurodegenerative process underlying AD, for instance, and self-discipline (including the ability to achieve a goal) plays a role in limiting health-risk behavior.
Openness to ideas was particularly revealing, being associated significantly with about a 25% reduced risk of AD for each SD higher score. The meta-analysis, with 607 cases of incident AD, also revealed significant associations for openness. It may be a logical extension that openness is related to lower risk of AD. The hallmarks of the open personality include being intellectually engaged and performing well on cognitive measures. Aspects of intelligence and education are associated with greater cognitive reserve and reduced risk of AD.
But, the researchers say, their novel finding that agreeable people have a reduced risk of AD should be interpreted with caution: None of the studies, including BLSA, found a significant association. Still, they point out, agreeableness measures interpersonal tendencies, and an inclination to be altruistic and cooperative “might facilitate the formation of interpersonal connections and the stability of social networks.” Physiologically speaking, the converse might be that people who score low on agreeableness tend to be aggressive, competitive, and antagonistic, which increases the risk of cardiovascular disease and, thus, AD.
Source
Terracciano A, Sutin AR, An Y, et al. Alzheimers Dement. 2014;10(2):179-186.
doi: 10.1016/j.jalz.2013.03.002.