new research shows.
Investigators analyzed data from almost 2,000 individuals enrolled in the Rush Memory and Aging Project (MAP) – a longitudinal study of older adults living in the greater Chicago metropolitan region and northeastern Illinois – with recruitment that began in 1997 and continues through today. Participants received a personality assessment as well as annual assessments of their cognitive abilities.
Those with high scores on measures of conscientiousness were significantly less likely to progress from normal cognition to mild cognitive impairment (MCI) during the study. In fact, scoring an extra 1 standard deviation on the conscientiousness scale was associated with a 22% lower risk of transitioning from no cognitive impairment (NCI) to MCI. On the other hand, scoring an additional 1 SD on a neuroticism scale was associated with a 12% increased risk of transitioning to MCI.
Participants who scored high on extraversion, as well as those who scored high on conscientiousness or low on neuroticism, tended to maintain normal cognitive functioning longer than other participants.
“Personality traits reflect relatively enduring patterns of thinking and behaving, which may cumulatively affect engagement in healthy and unhealthy behaviors and thought patterns across the lifespan,” lead author Tomiko Yoneda, PhD, a postdoctoral researcher in the department of medical social sciences, Northwestern University, Chicago, said in an interview.
“The accumulation of lifelong experiences may then contribute to susceptibility of particular diseases or disorders, such as mild cognitive impairment, or contribute to individual differences in the ability to withstand age-related neurological changes,” she added.
The study was published online in the Journal of Personality and Social Psychology.
Competing risk factors
Personality traits “reflect an individual’s persistent patterns of thinking, feeling, and behaving,” Dr. Yoneda said.
“For example, conscientiousness is characterized by competence, dutifulness, and self-discipline, while neuroticism is characterized by anxiety, depressive symptoms, and emotional instability. Likewise, individuals high in extraversion tend to be enthusiastic, gregarious, talkative, and assertive,” she added.
Previous research “suggests that low conscientiousness and high neuroticism are associated with an increased risk of cognitive impairment,” she continued. However, “there is also an increased risk of death in older adulthood – in other words, these outcomes are ‘competing risk factors.’”
Dr. Yoneda said her team wanted to “examine the impact of personality traits on the simultaneous risk of transitioning to mild cognitive impairment, dementia, and death.”
For the study, the researchers analyzed data from 1,954 participants in MAP (mean age at baseline 80 years, 73.7% female, 86.8% White), who received a personality assessment and annual assessments of their cognitive abilities.
To assess personality traits – in particular, conscientiousness, neuroticism, and extraversion – the researchers used the NEO Five Factor Inventory (NEO-FFI). They also used multistate survival modeling to examine the potential association between these traits and transitions from one cognitive status category to another (NCI, MCI, and dementia) and to death.
Cognitive healthspan
By the end of the study, over half of the sample (54%) had died.
Most transitions showed “relative stability in cognitive status across measurement occasions.”
- NCI to NCI (n = 7,368)
- MCI to MCI (n = 1,244)
- Dementia to dementia (n = 876)
There were 725 “backward transitions” from MCI to NCI, “which may reflect improvement or within-person variability in cognitive functioning, or learning effects,” the authors note.
There were only 114 “backward transitions” from dementia to MCI and only 12 from dementia to NCI, “suggesting that improvement in cognitive status was relatively rare, particularly once an individual progresses to dementia.”
After adjusting for demographics, depressive symptoms, and apolipoprotein (APOE) ε4 allele, the researchers found that personality traits were the most important factors in the transition from NCI to MCI.
Higher conscientiousness was associated with a decreased risk of transitioning from NCI to MCI (hazard ratio, 0.78; 95% confidence interval, 0.72-0.85). Conversely, higher neuroticism was associated with an increased risk of transitioning from NCI to MCI (HR, 1.12; 95% CI, 1.04-1.21) and a significantly decreased likelihood of transition back from MCI to NCI (HR, 0.90; 95% CI, 0.81-1.00).
Scoring ~6 points on a conscientiousness scale ranging from 0-48 (that is, 1 SD on the scale) was significantly associated with ~22% lower risk of transitioning forward from NCI to MCI, while scoring ~7 more points on a neuroticism scale (1 SD) was significantly associated with ~12% higher risk of transitioning from NCI to MCI.
Higher extraversion was associated with an increased likelihood of transitioning from MCI back to NCI (HR, 1.12; 95% CI, 1.03-1.22), and although extraversion was not associated with a longer total lifespan, participants who scored high on extraversion, as well as those who scored low on conscientiousness or low on neuroticism, maintained normal cognitive function longer than other participants.
“Our results suggest that high conscientiousness and low neuroticism may protect individuals against mild cognitive impairment,” said Dr. Yoneda.
Importantly, individuals who were either higher in conscientiousness, higher in extraversion, or lower in neuroticism had more years of “cognitive healthspan,” meaning more years without cognitive impairment,” she added.
In addition, “individuals lower in neuroticism and higher in extraversion were more likely to recover after receiving an MCI diagnosis, suggesting that these traits may be protective even after an individual starts to progress to dementia,” she said.
The authors note that the study focused on only three of the Big Five personality traits, while the other 2 – openness to experience and agreeableness – may also be associated with cognitive aging processes and mortality.
Nevertheless, given the current results, alongside extensive research in the personality field, aiming to increase conscientiousness through persistent behavioral change is one potential strategy for promoting healthy cognitive aging, Dr. Yoneda said.
‘Invaluable window’
In a comment, Brent Roberts, PhD, professor of psychology, University of Illinois Urbana-Champaign, said the study provides an “invaluable window into how personality affects the process of decline and either accelerates it, as in the role of neuroticism, or decelerates it, as in the role of conscientiousness.”
“I think the most fascinating finding was the fact that extraversion was related to transitioning from MCI back to NCI. These types of transitions have simply not been part of prior research, and it provides utterly unique insights and opportunities for interventions that may actually help people recover from a decline,” said Dr. Roberts, who was not involved in the research.
Claire Sexton, DPhil, Alzheimer’s Association director of scientific programs and outreach, called the paper “novel” because it investigated the transitions between normal cognition and mild impairment and between mild impairment and dementia.
Dr. Sexton, who was associated with this research team, cautioned that is it observational, “so it can illuminate associations or correlations, but not causes. As a result, we can’t say for sure what the mechanisms are behind these potential connections between personality and cognition, and more research is needed.”
The research was supported by the Alzheimer Society Research Program, Social Sciences and Humanities Research Council, and the National Institute on Aging of the National Institutes of Health. Dr. Yoneda and co-authors, Dr. Roberts, and Dr. Sexton have disclosed no relevant financial relationships.
A version of this article first appeared on Medscape.com.