New research finds that certain personality traits increase the risk of a dementia diagnosis, while others reduce the risk. Interestingly, no consistent association was found between personality and dementia-related brain pathology. The findings suggest that targeting personality traits early in life may be a way to reduce the risk of dementia in the long term.
Dementias have several different pathological underpinnings, the best known of which is Alzheimer's disease (AD), which is characterized by the accumulation of amyloid beta plaques and tau tangles. But there is a wealth of research showing a disconnect between the extent of a person's brain pathology and the clinical manifestations of cognitive impairment. About one-third of adults over the age of 75 have enough amyloid beta and tau to meet criteria for attention-deficit disorder, but do not suffer cognitive impairment.
Numerous meta-analyses suggest that physical, social, and cognitive engagement contribute to healthier cognitive aging. These factors are reflected in the "Big Five" personality traits: Consciousness, Extraversion, Openness to Experience, Neuroticism and Sociability. A new meta-analysis by researchers at the University of California, Davis, examined the links between personality traits and subjective well-being, neuropathology, and dementia diagnoses.
"We wanted to use new techniques to synthesize these studies and examine the strength and consistency of these associations," said Emorie Beck, first and corresponding author of the study.
The researchers analyzed data from eight published longitudinal studies spanning two continents and four countries. The studies included a total of 44,531 participants, 1,703 of whom developed dementia. They looked at how the Big Five personality traits and three aspects of subjective well-being - positive and negative emotions and life satisfaction - compared with clinical symptoms of dementia based on cognitive tests and post-mortem brain pathology.
They found that conscientiousness, extraversion and positive affectivity were protective against a diagnosis of dementia, while neuroticism and negative affectivity were risk factors. High scores on openness to experience, desirability, and life satisfaction have also been found to be protective in a small number of studies.
A reliable link between negative mood and dementia diagnosis is a new finding. Negative emotions are characterized by aversive emotional states such as anger, anxiety, disgust, guilt, and fear, and are highly correlated with neuroticism. Research shows that negative mood is associated with neuroinflammation, particularly in people with higher levels of amyloid beta, which may predispose people to depressive symptoms, creating a two-way pathway between inflammation and psychological factors. That is, depressive symptoms are related to inflammation, and inflammation may contribute to depressive symptoms.
Surprisingly, the researchers found no consistent association between personality traits and neuropathology in the postmortem dementia brain.
"This was the most surprising finding for us," Baker said. "If personality predicts performance on cognitive tests but not pathology, what might be going on?"
Researchers suggest that certain personality traits may make people more resilient to the cognitive impairments seen in dementia, and that those with higher personality traits may be able to cope with and resolve such impairments.
Taking into account other factors that might moderate the relationship between personality and dementia risk and neuropathology, such as age, gender and education, they found almost no association.
"We found little evidence of any effect, except that the protective effect of self-consciousness increased with age," Baker said.
An important limitation of this study is limited access to neuropathological markers; half of the samples did not complete autopsy, and all samples with neuropathological markers were from the United States.
The current meta-analysis replicates and extends previous research, providing strong evidence that neuroticism, self-consciousness, and negative affectivity are associated with a diagnosis of dementia across samples, across measures, and across time. Building on these findings, more research is needed, particularly on the temporality of these associations and the mechanisms underlying them.
The findings suggest that intervening on personality traits early in life may be a way to reduce the risk of long-term dementia.
The researchers plan to expand their work to include studying people with neuropathology but less cognitive impairment. They also hope to study other everyday factors that may play a role in the onset of dementia.
The research was published in the journal Alzheimer's & Dementia.