New research has found that some personality traits increase the risk of a dementia diagnosis, whereas others reduce it. Interestingly, no consistent association was seen between personality and dementia-related brain pathology. The findings suggest that targeting personality traits in interventions earlier in life may be a way of reducing dementia risk in the long term.
Several different pathologies underlie dementia, the most well-known being Alzheimer’s disease (AD), which is characterized by an accumulation of amyloid beta plaques and tau tangles. But there’s a body of research suggesting a disconnect between the degree of pathology in a person’s brain and the clinical manifestation of cognitive impairment. Around one-third of adults over 75 have sufficient amyloid beta and tau to meet the criteria for AD but are cognitively unimpaired.
Numerous meta-analyses indicate that physical, social, and cognitive engagement contribute to healthier cognitive aging. These factors are captured in the ‘Big Five’ personality traits: conscientiousness, extraversion, openness to experience, neuroticism, and agreeableness. A new meta-analysis by researchers at UC Davis has examined the link between personality traits and subjective well-being, and neuropathology and dementia diagnosis.
“We wanted to leverage new technology to synthesize these studies and test the strength and consistency of these associations,” said Emorie Beck, lead and corresponding author of the study.
The researchers analyzed data from eight published longitudinal studies spanning two continents and four countries. In total, the studies included 44,531 participants, 1,703 of whom developed dementia. They looked at measures of the Big Five personality traits and three aspects of subjective well-being – positive and negative affect and life satisfaction – compared to clinical symptoms of dementia based on cognitive tests and brain pathology at autopsy.
They found that conscientiousness, extraversion, and positive affect were protective against dementia diagnosis, whereas neuroticism and negative affect were risk factors. High scores on openness to experience, agreeableness and life satisfaction were also found to be protective in a smaller subset of studies.
The reliable association between negative affect and dementia diagnosis was a novel finding. Negative affect is characterized by aversive mood states like anger, anxiety, disgust, guilt, and fear and is highly related to neuroticism. Research has suggested that negative affect is associated with neuroinflammation, particularly for people with high levels of amyloid beta, and that inflammation may predispose individuals to depressive symptoms, creating a bidirectional pathway between inflammation and psychological factors. That is, depressive symptoms are related to inflammation, and inflammation may cause depressive symptoms.
Surprisingly, the researchers found no consistent associations between personality traits and the neuropathology seen in post-mortem dementia brains.
“This was the most surprising finding to us,” Beck said. “If personality is predictive of performance on cognitive tests but not pathology, what might be happening?”
The researchers propose that some personality traits might make people more resilient to the cognitive impairment seen in dementia and that those with higher levels of some traits may be able to cope with and work around this impairment.
Considering other factors that could moderate the relationship between personality and dementia risk and neuropathology, such as age, gender and education, they found little association.
“We found almost no evidence for effects, except that conscientiousness’ protective effect increased with age,” said Beck.
An important limitation of the study was the limited access to neuropathology markers; half of the samples did not complete autopsies, and all samples with neuropathology markers were from the US.
The current meta-analysis replicated and extended prior research, providing strong evidence that neuroticism, conscientiousness, and negative affect are associated with dementia diagnoses across samples, measures, and time. More research is needed to build upon these findings, particularly the timing of these associations and the mechanisms underlying them.
What the findings suggest is that targeting personality traits for intervention earlier in life might be a way of reducing long-term dementia risk.
The researchers plan to expand their work, including looking at people with neuropathology but little cognitive impairment. They also hope to examine other everyday factors that might play a role in developing dementia.
The study was published in the journal Alzheimer’s & Dementia.
Source: UC Davis