Emotion dysregulation and psychological inflexibility in adolescents: Discriminant validity and associations with internalizing symptoms and functional impairment

Emotion dysregulation and psychological inflexibility are widely regarded as key contributors to a range of mental health issues and are integral to several treatment models in the mental health field. However, no study has examined whether the two constructs reflect distinct aspects of psychological functioning or whether they can be clearly differentiated from mental health symptoms and associated impairment. Adolescence is a key period for the onset of mental health problems, making a better understanding of psychological processes involved in mental health in this age group important. The Difficulties in Emotion Regulation Scale (DERS-16, emotion dysregulation) and the Avoidance and Fusion Questionnaire for Youth (AFQ-Y8, psychological inflexibility) are widely used assessment tools of emotion dysregulation and psychological inflexibility, but critical evaluations of their validity are sparse. Using exploratory and confirmatory factor analysis, we examined the discriminant validity of emotion dysregulation and psychological inflexibility as measured via the DERS-16 and the AFQ-Y8 in a sample of 633 adolescents (M_age = 16.6 [1.98]). Emotion dysregulation and psychological inflexibility did not demonstrate discriminant validity. Instead, four strongly correlated factors emerged, each comprising a combination of items from both assessment tools: (1) interference stemming from distressing thoughts and emotions, (2) negative self-evaluation, (3) loss of control when emotional, and (4) confusion about one's emotions. These factors were strongly correlated and adequately captured by an overarching factor, which we termed the X factor, which in turn was very strongly correlated with core symptoms of anxiety and depression and functional impairment stemming from mental health issues. In conclusion, the constructs of emotion dysregulation and psychological inflexibility, as assessed by the DERS-16 and AFQ-Y8, do not show discriminant validity in adolescents. Furthermore, the constructs measured by these tools are almost empirically indistinguishable from anxiety, depression, and functional impairment.