Background: Omega-3 fatty acid (O3FA) levels and dimensional personality measures have been associated with major depression and the course of depressive illness. We sought to study the utility of O3FA levels and dimensional personality measures as predictors of early improvement with escitalopram.

Methods: Twenty-four participants were enrolled in an open-label trial of escitalopram 10 mg/d for 4 weeks. Baseline erythrocyte O3 levels and dimensional personality assessments were obtained.

Results: Using a conservative, intention-to-treat analysis, baseline neuroticism (r = –0.57; P = .007), as measured by the Revised NEO Personality Inventory but not erythrocyte O3 levels, was correlated with improvements on escitalopram. A facet analysis of the neuroticism domain showed the relationship with antidepressant response to be focused on trait anxiety (r = –0.65; P = .002).

Conclusions: Anxiety may have important prognostic implications on subsequent response to selective serotonin reuptake inhibitors, such as escitalopram.