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.

重要性  行为和性格改变是痴呆症诊断的一项标准。但是，尚不清楚这种改变是否在疾病的临床发作之前开始。

目的  确定在轻度认知障碍或痴呆发作之前是否出现神经质增加，自觉性下降以及其他人格特质的变化。

设计，环境和参与者  纳入了2046名自愿参加巴尔的摩纵向老龄化研究的社区居住的老年人。这项研究调查了1980年至2016年7月13日期间首次随访时无认知障碍的受试者的人格和临床评估，随访时间长达36年（平均[SD]，12.05 [9.54]年）。在共识诊断会议期间未考虑自我报告人格量表。

主要结果和衡量指标：  使用经修订的NEO人格量表在阿尔茨海默氏病和其他痴呆症的临床前阶段评估的自我评价人格特征的变化，这是一项240项问卷，评估了30个方面，其中5个主要方面分别有6个方面：神经质，性格外向，开放，友善和尽责。

结果  在2046名参与者中，有931名[45.5％]是女性；首次评估的平均（SD）年龄为62.56（14.63）岁。在24569人年期间，在104（5.1％）个人中诊断出轻度认知障碍，在255（12.5％）人中诊断出全因痴呆，其中包括194（9.5％）的阿尔茨海默病。涉及年龄，性别，种族和教育水平的多层次建模在几个特征的截距上发现了显着差异：发展为痴呆的个体在神经质方面得分更高（β= 2.83； 95％CI，1.44至4.22；P  <.001）尽责程度较低（β= -3.34; 95％CI，-4.93至-1.75; P  <.001）和外向性（β= -1.74; 95％CI，-3.23至-0.25; P = .02）。但是，在未受损人群和阿尔茨海默氏症人群之间，人格变化（即斜率）没有显着差异（例如，神经质：β= 0.00； 95％CI，-0.08至0.08；P  = 0.91；尽职调查：β= -0.06； 95％CI，-0.16至0.04；P  = 0.24）。出现轻度认知障碍（例如神经质：β= 0.00; 95％CI，-0.12至0.12; P  = 0.98;尽职调查：β= -0.09; 95％CI，-0.23至0.05; P  =。 18）和所有原因的痴呆症（例如神经质性：β= 0.02; 95％CI，-0.06至0.10; P  = 0.49;尽职调查：β= -0.08; 95％CI，-0.16至0.00; P  = .07 ）也与未受损参与者的相似。

结论与相关性  在轻度认知障碍或痴呆发作之前，尚无人格前临床改变的证据。这些发现为逆向因果假设提供了证据，并加强了人格特质作为痴呆症危险因素的证据。