Neuroticism: moderator or mediator in the relation between locus of control and depression?

The present investigation examined empirically the influence of neuroticism on the relation between locus of control and depression, first as a moderator with specified interaction effects, and secondly as a mediator in the path from locus of control to depression. Levenson's internality, powerful others and chance (IPC) locus of control scales, the Eysencks' EPQ-R neuroticism scale and a depression inventory were completed by 162 university students aged 17-57 years (mean = 27.9, SD = 10.3). There were no significant differences between sexes on any mean score. Controlling for sex and age, externality, neuroticism and depression were significantly correlated (p < 0.001), but only chance locus of control and neuroticism predicted depression. In the absence of significant interaction and quadratic effects, multiple regression analyses did not support neuroticism as a moderator, but as a partial mediator in the relationship between chance locus of control and depression. Path analysis showed that the total effect size was very large. The influence of neuroticism was discussed in terms of the "depressive paradox" (self-blame and uncontrollability co-existing in depressed individuals), the multidimensional aspects of locus of control, and implications for treating depression. (C) 2003 Elsevier Ltd. All rights reserved.