Trait neuroticism, depression, and cognitive function in older primary care patients.

OBJECTIVE: Prior studies on the association of trait neuroticism and cognitive function in older adults have yielded mixed findings. The authors tested hypotheses that neuroticism is associated with measures of cognition and that depression moderates these relationships.
DESIGN: Cross-sectional observational study.
SETTING: Primary care offices. PARTICIPANTS: Primary care patients aged > or =65 years. MEASUREMENTS: Trait neuroticism was assessed by the NEO-Five Factor Inventory. Major and minor depressions were determined by the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, and depressive symptom severity by the Hamilton Depression Rating Scale (Ham-D). Cognitive measures included the Mini-Mental State Examination (MMSE), Initiation-Perseveration subscale of the Mattis Dementia Rating Scale, and Trail-Making tests A and B.
RESULTS: In multiple regression analyses, neuroticism was associated with MMSE score independent of depression diagnosis (beta = -0.04, chi2 = 14.2, df = 1, p = 0.0002, 95% confidence interval [CI] = -0.07 to -0.02) and Ham-D score (beta = -0.04, chi2 = 8.97, df = 1, p = 0.003, 95% CI = -0.06 to -0.01). Interactions between neuroticism and depression diagnosis (chi2 = 7.21, df = 2, p = 0.03) and Ham-D scores (chi2 = 0.55, df = 1, p = 0.46) failed to lend strong support to the moderation hypothesis.
CONCLUSION: Neuroticism is associated with lower MMSE scores. Findings do not confirm a moderating role for depression but suggest that depression diagnosis may confer additional risk for poorer global cognitive function in patients with high neuroticism. Further study is necessary.