Theory of Mind in Depressive Disorders: A Review of the Literature

Abstract

Background: Theory of mind (ToM) is the ability to infer the mental states of others in order to understand and predict their behaviour. This ability is thought to be essential to social functioning and interpersonal relationships. As major depression is characterized by considerable social and interpersonal difficulties, exploration of the quality of ToM functioning can be particularly relevant in this and in related disorders. We aim to review the current state of research on ToM in depressive disorders in order to find out the extent to which ToM impairment is associated with these illnesses. Methods: An internet database search was carried out to collect all publications on the subject. Results: A total of 32 publications in English met our inclusion criteria: (a) 17 studies on ToM in major depression, (b) 4 studies on ToM in psychotic depression, (c) 3 studies on ToM in dysphoria or mild depression, (d) 4 studies on ToM in euthymic major depression, (e) 2 studies on ToM in chronic versus episodic depression, and (f) 2 studies on ToM in another psychiatric disorder with comorbid major depression. Conclusions: Despite an increased interest in the research of the topic in recent years, no firm conclusions can be drawn, as the reviewed articles present some conflicting results. Acutely depressed patients have been found to be impaired on tasks involving both ToM social-perceptual and social-cognitive components. On the other hand, a number of studies have not reported significant between-group differences between depressed patients and healthy controls or have found minimal differences. Further research is needed in order to confirm and extend these results.