The relationship between self-harm and alexithymia: a systematic review and meta-analysis

Self-harm, defined for the purpose of this review as any act of self-injury without explicit suicidal intent, is an increasing public health concern, with potential long-term implications for those who engage in it. Previous research has identified a correlational relationship between self-harm and alexithymia, an emotion processing deficit characterised by difficulties identifying and describing feelings, and an externally-orientated thinking style. Through a systematic search of the literature, the current review examines the association between alexithymia and self-harm. A meta-analysis based on 23 studies found a significant, positive relationship between self-harm and alexithymia, with a medium effect size (g = 0.57, 95% CI 0.45 to 0.71). All 23 studies used the Toronto Alexithymia Scale (TAS20) to measure alexithymia. The alexithymia subcomponents difficulty identifying feelings and difficulty describing feelings were significantly associated with self-harm, but there was no significant association between self-harm and externally-orientated thinking. The effect size of the relationship was significantly larger in adolescent samples compared with adult samples and in female compared with male samples. The definition of self-harm did not affect the effect size of the relationship between alexithymia and self-harm and the results are consistent with previous meta-analyses focused more narrowly on non-suicidal self-injury and, separately, suicidal behaviours. Heterogeneity between the included studies was high. The results support an affect regulation model of self-harm, in which self-harm is used to regulate an emotional experience that is poorly understood