Personality Change in the Preclinical Phase of Alzheimer Disease

Abstract

Importance: Changes in behavior and personality are 1 criterion for the diagnosis of dementia. It is unclear, however, whether such changes begin before the clinical onset of the disease.

Objective: To determine whether increases in neuroticism, declines in conscientiousness, and changes in other personality traits occur before the onset of mild cognitive impairment or dementia.

Design, setting, and participants: A cohort of 2046 community-dwelling older adults who volunteered to participate in the Baltimore Longitudinal Study of Aging were included. The study examined personality and clinical assessments obtained between 1980 and July 13, 2016, from participants 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 self-report personality scales were not considered during consensus diagnostic conferences.

Main outcomes and measures: Change in self-rated personality traits assessed in the preclinical phase of Alzheimer disease and other dementias with the Revised NEO Personality Inventory, a 240-item questionnaire that assesses 30 facets, 6 for each of the 5 major dimensions: neuroticism, extraversion, openness, agreeableness, and conscientiousness.

Results: Of the 2046 participants, 931 [45.5%] were women; mean (SD) age at first assessment was 62.56 (14.63) years. During 24 569 person-years, mild cognitive impairment was diagnosed in 104 (5.1%) individuals, and all-cause dementia was diagnosed in 255 (12.5%) participants, including 194 (9.5%) with Alzheimer disease. Multilevel modeling that accounted for age, sex, race, and educational level found significant differences 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). Change in personality (ie, slope), however, was not significantly different between the nonimpaired and the Alzheimer 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 also similar to those for nonimpaired participants.

Conclusions and relevance: No evidence for preclinical change in personality before the onset of mild cognitive impairment or dementia was identified. These findings provide evidence against the reverse causality hypothesis and strengthen evidence for personality traits as a risk factor for dementia.

Figure 1.. Hypothetical Personality Changes in Preclinical Alzheimer Disease

The H1 line represents the hypothesis that personality (eg, conscientiousness) changes before the onset of clinical dementia compared with no preclinical change (H0).

Figure 2.. Sample Selection at Baseline and Cognitive Outcomes at Follow-up

BLSA indicates Baltimore Longitudinal Study of Aging; MCI, mild cognitive impairment.

Figure 3.. Personality Trajectories Over the Last 2 Assessments Before the Onset of AD Compared With Those With No Cognitive Impairment

Changes in neuroticism and conscientiousness for 131 individuals who later developed Alzheimer disease (AD) and 1374 individuals with no cognitive impairment. The AD group was tested an average of 6.44 (time −2) and 3.47 (time −1) years before the onset of the disease. At time −2, the mean (SD) age was 77.58 (7.95) years. The AD group scored higher on neuroticism and lower on conscientiousness before the onset of the disease. Contrary to expectations, the AD group did not increase in neuroticism or decline in conscientiousness in the preclinical phase of the disease.