Is self-disgust the emotional trigger that leads to self-harm?

To help people who perform non-lethal self-harm, such as cutting and burning themselves, we need a better understanding of the thoughts and feelings that contribute to them resorting to this behaviour. Risk factors are already known, including depression and a history of sexual abuse. However, Noelle Smith and her colleagues wondered if these factors increase the risk of self-harm because they lead people to experience self-disgust. Viewed this way, the researchers believe "self-disgust may serve as an emotional trigger" for self-harm.

Over five hundred undergrads, men and women, answered questions about whether they'd ever intentionally harmed themselves (including cutting, burning and scratching); when they'd last performed such an act; their depression symptoms; any history of physical or sexual abuse; their anxiety; and crucially, their feelings of self-disgust, as measured by 18 items, such as "I find myself repulsive".

Consistent with the researchers' predictions, the more self-disgust a student reported, the greater the likelihood that they had previously performed self-harm (statistically speaking, a one standard deviation increase in self-disgust was associated with a two-fold increase in the odds of reporting self-harm).

Levels of self-disgust were the highest in those students who said they'd performed self-harm in the last year. These were also the same students who tended to report depression symptoms and a history of physical or sexual abuse. It's notable though, that depression was no longer associated with self-harm once self-disgust was taken into account, suggesting that self-disgust is the key mediating factor.

These findings jibe with past research on the more cognitive aspects of self-disgust - for example, there's evidence that self-harm is associated with being self-critical and having an excessive focus on one's own mistakes. Other studies have highlighted reductions in self-disgust after acts of self-harm, but also increases. Smith and her colleagues suggested the link could be bi-directional: self-harm may assuage feelings of disgust with self, but performing a self-harming act may then trigger feelings of shame with one's own actions.

The cross-sectional nature of this study means it can't shed light on the direction of causality -  whether self-disgust contributes to self-harm behaviours, or if the reverse is true. Self-disgust was also measured as trait, rather than as an acute state of mind. The researchers acknowledged these issues, but they note theirs is the first study to look at the emotion of self-disgust as a precipitating factor for self-harm, and they call for more research. For now, they said their results suggest reducing self-disgust may help people who are at risk of self-harm.

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Smith, N., Steele, A., Weitzman, M., Trueba, A., & Meuret, A. (2015). Investigating the Role of Self-Disgust in Nonsuicidal Self-Injury Archives of Suicide Research, 19 (1), 60-74 DOI: 10.1080/13811118.2013.850135

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.