Altered reward network responses to social touch in major depression

Abstract

AbstractIntroductionAffective touch is highly rewarding and an integral part of social relationships. Major depressive disorder (MDD) is characterized by severe impairments in reward processing, but the neural effects of social touch in MDD are still elusive.ObjectiveWe aimed to determine whether the neural processing of social touch is impaired in MDD and to assess the impact of antidepressant therapy.MethodsBefore and after antidepressant treatment, 53 MDD patients and 41 healthy controls underwent functional magnetic resonance imaging (fMRI) while receiving social touch. We compared neural responses to social touch in the reward network, behavioral ratings of touch comfort and general aversion to interpersonal touch in MDD patients to controls. Additionally, we examined the effect of treatment response on those measures.ResultsClinical symptoms decreased after treatment and 43.4% of patients were classified as responders. Patients reported higher aversion to social touch and lower comfort ratings during the fMRI paradigm than controls. Patients showed reduced responses to social touch in the nucleus accumbens, caudate nucleus and putamen than controls, both before and after treatment. Non-responders exhibited blunted response in the caudate nucleus and the insula compared to responders, again irrespective of treatment.ConclusionsThese findings confirm our hypothesis that interpersonal touch as an indicator of social reward processing is impaired in MDD. Persistent dysfunctional processing of social touch despite clinical improvements may constitute a latent risk factor for social withdrawal and isolation. New treatment approaches are necessary to specifically target social reward processing and disturbed body awareness in MDD.