Use of the five-factory inventory in characterizing patients with major depressive disorder

Research on personality traits has suggested an association between depression and certain personality traits, such as neuroticism and extraversion. Costa and McCrae's five-factor personality inventory (NEO) has been shown to measure personality traits in a nonclinical population, but its use has not been fully explored in clinical populations. This study aims to compare NEO results in a sample of depressed outpatients with published test norms, and determine if different levels of neuroticism and extraversion are associated with differences in certain psychosocial and clinical characteristics. Seventy-six depressed outpatients participating in antidepressant clinical trials completed this self-report questionnaire before beginning pharmacological treatment. Diagnosis of major depressive disorder (MDD) was made using the Structured Clinical Interview for DSM-III-R or DSM-IV and the severity of depression was measured with the 17-item Hamilton Depression Rating Scale (HAM-D). The three analyses conducted were as follows: (1) NEO factor scores were compared with published normative means; (2) three groups, based on level of neuroticism, were compared on certain psychosocial and clinical characteristics; and (3) three groups, based on level of extraversion, were compared on the same psychosocial and clinical characteristics. Both the males and females obtained T score values for the Neuroticism Scale 1.5 SD above the mean, for the Extraversion Scale 1.5 SD below the mean, and for the Conscientiousness Scale 1.5 SD below the mean. No significant differences were found between subjects with different levels of neuroticism and extraversion, although a trend did exist indicating a positive relationship between neuroticism and severity of depression. Depressed outpatients experience frequent negative affects, have irrational thought processes, cope with stress poorly, have difficulty controlling impulses, prefer to be alone, and have difficulty carrying out tasks. Future studies should examine how such personality factors affect response to treatment and course of illness.