Associations of red blood cell fatty acids with personality traits: 10-year follow-up in the Kibbutzim Family Study

BACKGROUND: The ability of hostility and Type-A personality to predict cardiovascular outcomes makes understanding antecedents of these personality traits an important public health objective. OBJECTIVE: We examined whether blood-measured fatty acids (the exposure) are associated with hostility and Type-A personality (the outcome), while accounting for lifestyle, sociodemographic factors and polygenic background. METHODS: Personality traits, sociodemographic and lifestyle data were obtained in 1992-93 from 452 family members living in kibbutz settlements in Israel (Visit 1) and re-measured 8-10 years later in 379 individuals (Visit 2). Red blood cell fatty acid levels were determined in Visit 1 by gas chromatography. Longitudinal associations of Visit 1 fatty acids with Visit 2 personality traits were examined using linear models, before and after controlling for baseline personality scores. The contribution of the environmental factors to personality scores beyond heritability was estimated by variance decomposition. RESULTS: In longitudinal analysis, 1% increase in Visit 1 Total n-6 fatty acid was associated with a 0.328-unit decrease in Visit 2 Type-A score (95% confidence interval (CI): -0.571, -0.085). After adjustment for baseline personality levels, the association was slightly attenuated (β=-0.204; CI: -0.399, -0.009). One-percent higher Total n-6 was also associated with 1.119 units lower Visit 2 hostility score (CI: -2.777, 0.038; p=0.055). Finally, independent of the genetic contribution (32%-38% of adjusted variability in hostility and Type-A personality), a 1% increase in Total n-3 and Total n-6 was associated with 2.539 (CI: -3.907, -1.171) and 0.201 (CI: -0.365, -0.037) unit lower hostility and Type-A scores, respectively. CONCLUSIONS: Higher RBC Total n-6 fatty acid levels were associated with lower Type-A personality scores. After adjustment for baseline personality levels, the associations between Total n-6 and hostility and between Total n-3 and hostility were attenuated. These findings support further investigation of the relationship between fatty acid biology and personality traits using study designs better suited to causal inference.