Does emotion regulation mediate the relationship between interoception/alexithymia and co-morbid depression/anxiety? Evidence from two independent samples

Previous work suggests that interoception - the capacity to detect and interpret internal states of the body - may be disrupted in affective disorders. A related body of work suggests that reduced understanding of how interoceptive sensations relate to emotions (alexithymia) is also linked to these disorders. One route by which these deficits could maintain affective symptoms is poor emotion regulation - as perception and regulation of internal states share bidirectional links. However, depression and anxiety symptoms are highly co-morbid, and it remains unclear whether one or both are primarily affected. In this study, we sought to replicate prior results suggesting emotion dysregulation mediates the relationship between interoception/alexithymia and depressive symptoms, and to further determine whether co-morbid anxiety plays an additional, or alternative, explanatory role. Participants in two consecutive, non-clinical samples (Sample 1: N = 445, Mage=23.68; Sample 2: N = 196, Mage=24.99) completed measures of interoception (MAIA), alexithymia (TAS-20), emotion dysregulation (DERS), depression (BDI-II), and anxiety (STAI). Results in both samples confirmed that emotion dysregulation mediated the relationship between interoception and depressive symptoms and found a similar relationship with trait anxiety. When accounting for co-morbidity, anxiety - and not depression - appeared to best explain previous findings for interoception. In contrast, results suggested that depression - and not anxiety - explained prior links to alexithymia. These results may help guide interpretation of prior results when considering the high comorbidity in depression and anxiety symptoms and suggest unique treatment targets for each. Future research should examine these measures in clinical samples and with longitudinal data that can better disentangle the directional nature of these relationships.