UC Merced Undergraduate Research Journal

Researchers have developed multiple approaches to treat major depressive disorder (MDD). Clinicians commonly employ antidepressant medication (ADM) and psychotherapy as treatment protocols. This review surveys the knowledge and identifies problems with the effects of personality and temperament for MDD treatment in 14 quantitative studies. High extraversion and conscientiousness have a positive effect on psychotherapy treatment while high neuroticism has a negative effect. Agreeableness and openness to experience appear to have conflicting results. All individual traits do not influence ADM treatment except for high and low reward dependence, which may be better for psychotherapy and ADM respectively. Low persistence and high harm avoidance adversely affect psychotherapy, but novelty seeking has an insignificant effect. Some problems in the literature include the self-report measures for individual traits, heterogeneity of study designs, and the complexity of defining personality and temperament. This paper is limited to ADM by SSRIs, SNRIs, and tricyclic antidepressants. These findings may assist patients in choosing treatment types and clinicians in creating better treatment plans for patients, especially psychotherapy. This article may also contribute to the reconceptualization of mental disorders as a dimension instead of a type.