Johnson, Travis A.

Background/Objectives Behavioral problems in individuals with Alzheimer's disease ( AD ) impose major management challenges. Current prevention strategies are anchored to cognitive outcomes, but behavioral outcomes may provide another, clinically relevant opportunity for preemptive therapy. We sought to determine whether personality changes that predispose to behavioral disorders arise during the transition from preclinical AD to mild cognitive impairment ( MCI ). Design Longitudinal observational cohort study. Setting Academic medical center. Participants Members of an apolipoprotein E ( APOE ) ɛ4 genetically enriched cohort of Maricopa County residents who were neuropsychiatrically healthy at entry (N = 277). Over a mean interval of 7 years, 25 who developed MCI and had the Neuroticism, Extraversion, and Openness Personality Inventory—Revised ( NEO ‐ PI ‐R) before and during the MCI transition epoch were compared with 252 nontransitioners also with serial NEO ‐ PI ‐R administrations. Intervention Longitudinal administration of the NEO ‐ PI ‐R and neuropsychological test battery. Measurements Change in NEO ‐ PI ‐R factor scores (neuroticism, extraversion, openness, agreeableness, conscientiousness) from entry to the epoch of MCI diagnosis or an equivalent follow‐up duration in nontransitioners. Results NEO ‐ PI ‐R neuroticism T‐scores increased significantly more in MCI transitioners than in nontransitioners (mean 2.9, 95% confidence interval ( CI ) = 0.9–4.9 vs 0, 95% CI = −0.7–0.7, P = .02), and openness decreased more in MCI transitioners than in nontransitioners (−4.8, 95% CI = −7.3 to −2.4 vs −1.0, 95% CI = −1.6 to −0.4, P < .001). Concurrent subclinical but statistically significant changes in behavioral scores worsened more in MCI transitioners than nontransitioners for measures of depression, somatization, irritability, anxiety, and aggressive attitude. Conclusion Personality and subclinical behavioral changes begin during the transition from preclinical AD to incident MCI and qualitatively resemble the clinically manifest behavioral disorders that subsequently arise in individuals with frank dementia.