Tracking change in personality as early indicator of dementia may be futile
Changes in personality traits do not occur prior to the onset of mild cognitive impairment (MCI) or Alzheimer’s disease (AD), a study has shown.
“The trajectory of personality traits and facets for individuals who were later diagnosed with MCI or dementia did not differ significantly from that of nonimpaired older adults,” according to a team of investigators from the Florida State University. “These findings provide evidence against the reverse causality hypothesis and strengthen evidence for personality traits as a risk factor for dementia.”
Using data from the Baltimore Longitudinal Study of Aging, the investigators analysed personality and clinical assessments obtained over 36 years from 2,046 community-dwelling older adults (mean age at first assessment 62.56 years; 45.5 percent female) with no cognitive impairment at baseline.
All participants completed the Revised NEO Personality Inventory, a 240-item questionnaire evaluating six facets for each of the five major dimensions: neuroticism, extraversion, openness, agreeableness and conscientiousness.
During 24,569 person-years, 104 (5.1 percent) participants developed MCI and 255 (12.5 percent) were diagnosed with all-cause dementia, including 194 (9.5 percent) with AD. Participants with dementia scored significantly higher on neuroticism (p<0.001) and lower on conscientiousness (p<0.001) and extraversion (p=0.02) relative to those without cognitive impairment. [JAMA Psychiatry 2017;doi:10.1001/jamapsychiatry.2017.2816]
However, the rate of change in personality traits was similar between the AD and nonimpaired groups (eg, neuroticism, p=0.91; conscientiousness, p=0.24). There was also no evidence of accelerated change in personality in the MCI group (eg, neuroticism, p=0.98; conscientiousness, p=0.18) and all-cause dementia group (eg, neuroticism, p=0.49; conscientiousness, p=0.07) vs the nonimpaired group.
“We further found that personality remained stable even within the last few years before the onset of the disease, and the high rank-order correlations supported the reliability of the data,” the investigators said.
The differences of approximately 0.3-SD between the AD and nonimpaired groups on the intercept of neuroticism and conscientiousness were said to be not an emerging prodromal sign of the disease and were in line with results from other prospective studies. [Alzheimers Dement 2014;10:179-186; J Psychiatr Res 2017;89:22-27]
“From a clinical perspective, these findings suggest that tracking change in self-rated personality as an early indicator of dementia is unlikely to be fruitful, while a single assessment provides reliable information on the personality traits that increase resilience (eg, conscientiousness) or vulnerability (eg, neuroticism) to clinical dementia,” they continued.
The investigators pointed out that the lack of evidence suggesting that neuroticism and conscientiousness changed significantly as the onset of the disease approached indicates that such traits may confer risk for the development of AD rather than an effect of disease neuropathology.
The study is not without limitations. Among those that were cited included the use of a selective sample with a higher educational level and the relatively younger age of nonimpaired participants.
“More research is needed on personality and AD biomarkers, and how personality may increase resilience against neuropathology and forestall the emergence of clinical dementia,” the investigators said.