Terracciano A, et al. - This research investigated if increases in neuroticism, declines in conscientiousness, and changes in other personality traits occurred prior to the onset of mild cognitive impairment or dementia. There did not appear to be any evidence with regard to the preclinical variation in personality prior to the detection of the onset of mild cognitive impairment or dementia. The current trial yielded evidence against the reverse causality hypothesis. Moreover, it strengthened the evidence for personality traits serving as a risk factor for dementia.

Methods

• This trial enrolled 2046 community-dwelling older adults who volunteered to take part in the Baltimore Longitudinal Study of Aging.
• The personality and clinical assessments obtained between 1980 and July 13, 2016 were inspected, from the enrollees with no cognitive impairment at first assessment who were followed up for as long as 36 years (mean [SD], 12.05 [9.54] years).
• The study did not include the self-report personality scales during consensus diagnostic conferences.
• The main outcome measure included the variation in self-rated personality traits analyzed in the preclinical phase of Alzheimer's disease and other dementias with the Revised NEO Personality Inventory, a 240-item questionnaire that inspected 30 facets, 6 for each of the 5 major dimensions: Neuroticism, extraversion, openness, agreeableness, and conscientiousness.

Results

• Among the 2046 participants, 931 [45.5%] were women; mean (SD) age at first assessment was 62.56 (14.63) years.
• During 24569 person-years, mild cognitive impairment was diagnosed in 104 (5.1%) subjects, and all-cause dementia was diagnosed in 255 (12.5%) participants, including 194 (9.5%) with Alzheimer's disease.
• Multilevel modeling considering age, sex, race, and educational level unveiled marked variations on the intercept of several traits: Individuals who developed dementia scored higher on neuroticism (β = 2.83; 95% CI, 1.44 to 4.22; P < .001) and lower on conscientiousness (β = -3.34; 95% CI, -4.93 to -1.75; P < .001) and extraversion (β = -1.74; 95% CI, -3.23 to -0.25; P = .02).
• Nevertheless, the variation in personality (ie, slope) did not considerably vary between the nonimpaired and the Alzheimer's disease groups (eg, neuroticism: β = 0.00; 95% CI, -0.08 to 0.08; P = .91; conscientiousness: β = -0.06; 95% CI, -0.16 to 0.04; P = .24).
• Slopes for individuals who developed mild cognitive impairment (eg, neuroticism: β = 0.00; 95% CI, -0.12 to 0.12; P = .98; conscientiousness: β = -0.09; 95% CI, -0.23 to 0.05; P = .18) and all-cause dementia (eg, neuroticism: β = 0.02; 95% CI, -0.06 to 0.10; P = .49; conscientiousness: β = -0.08; 95% CI, -0.16 to 0.00; P = .07) were determined as being similar to those for nonimpaired enrollees.