Abnormal body perception and neural activity in the insula in depression: An fMRI study of the depressed “material me”

Abstract

Objectives. In addition to affective-cognitive symptoms, patients with major depressive disorder (MDD) suffer from somato-vegetative symptoms, suggesting abnormal interoceptive awareness of their “material me”. While recent imaging studies have extensively investigated affective-cognitive symptoms in MDD, the neural correlates of somato-vegetative symptoms and abnormal interoception remain unclear. Since the “material me” has been especially associated with the anterior insula in healthy subjects, we hypothesized abnormalities in this region during interoceptive awareness in MDD. Methods. We therefore investigated behavioural and neural correlates of interoception in healthy and depressed subjects using the Body Perception Questionnaire (BPQ) and a well established heartbeat perception task in fMRI. Results. MDD patients showed significantly higher scores in the BPQ and reduced neural activity during rest periods, particularly in the bilateral anterior insula. In contrast to healthy subjects, BPQ scores no longer correlated with activity during rest periods in the anterior insula. Both BPQ scores and left anterior insula signal changes correlated with depression severity. Conclusions. We demonstrate for the first time abnormal body perception and altered activity in the insula during rest in MDD. Our results suggest that these behavioural and neural abnormalities are closely related to these patients’ somato-vegetative abnormalities and their abnormal “material me”.

Key words::

• Major depressive disorder
• functional magnetic resonance imaging
• awareness
• insular cortex
• self concept
• mind-body relations

Acknowledgements

We thank the staff from the state hospital of Uchtspringe, the Department of Neurology and Lilly Germany for their skilful assistance as well as Björn Enzi for his helpful comments on the manuscript. The study was made possible by financial contributions from Lilly Germany (to GN), the Salus Foundation (to GN), the Hope of Depression Research Foundation (HDRF, to GN) and the German Research Foundation (DFG, Sonderforschungsbereich 779-A6, to GN and CW).

Statement of interest

The authors report no conflict of interests.