is often repeated, resulting in extensive scarring patterns. The age 
of onset of NSSI tends to be early adolescence, between 12 and 
14 years of age, and the behavior appears to decline after young 
adulthood (Nock et al. 2009).
The phenomenology of NSSI is still elusive. It has been hypoth-
esized that self-injury behaviors might be engaged to regulate 
emotions by avoiding or distracting from unwanted emotional 
experiences (e.g. shame) or negative beliefs about the self (Chap-
man et al. 2006). This “affect regulation hypothesis” is sup-
ported by the findings that emotional dysregulation—such as 
reduced emotional clarity, problems in goal-directed behaviors, 
and impulse control—is common in non-clinical samples of ado-
lescents who engage in NSSI. The probability of engaging in 
self-injuries appears to be positively associated with emotional 
dysregulation, particularly when individuals lack more adaptive 
strategies (e.g. reappraisal) to cope with their affectivity (Wolff 
et al. 2019). Likewise, self-injurers typically describe their behav-
iors as attempts to avoid negative cognitive (i.e. bad thoughts or 
memories) and affective (i.e. anxiety, sadness, and anger) states, 
whose elevated arousal is suggested to increase the likelihood 
of engaging in self-injuries (Nock and Mendes 2008b, Nock et al. 
2009). The interplay between physiological hyperarousal, poor dis-
tr
ess tolerance, and reduced problem-solving skills is thought to 
concur in self-injury behaviors (Nock and Prinstein 2004 , Nock 
et al. 2006), with adolescents with a history of NSSI displaying 
greater changes in skin conductance and reduced tolerance to 
increasingly stressing conditions (Nock and Mendes 2008b).
A factor that might contribute to the genesis of maladaptive 
behaviors—including NSSI—is the extent to which one is able to 
sustain the rise in the levels of uncertainty, which, broadly speak-
ing, might occur in different domains of subjective experience 
(from bodily states to the possible outcomes of social interac-
tions, to the self, and to one’s personal identity). Every day, we 
face some kind of uncertainty, but the degree to which it might be 
distressing largely varies across individuals. High levels of intoler-
ance of uncertainty, or the attitude to react negatively to uncertain 
situations and events (Ladouceur et  al. 2000), are considered a 
transdiagnostic vulnerability factor across several clinical condi-
tions such as anxiety, depression (McEvoy and Mahoney 2012 ), 
and eating disorders (Kesby et al. 2017). Recently, such “fear for 
uncertainty” has also been reported in neurotypical young adults 
and adolescents in relation to excessive worry (Laugesen et al. 
2003, T
hielsch et al. 2015) and anxiety (Osmana ̆gao ̆glu et al. 2018). 
There is also evidence of a positive reciprocal association between 
intolerance of uncertainty and difficulties in emotion processing 
in adolescents and that both tend to decrease with the transition 
to adulthood (Lauriola et  al. 2023). Crucially, NSSI is particularly 
prominent in adolescence; its rate in non-clinical samples of ado-
lescence has increased alarmingly in this century, representing a 
serious ongoing societal health concern (Xiao et al. 2022).
NSSI in adolescence
Adolescence is the period of developmental transition from child-
hood to adulthood, which might be stretched up to the early 
20s due to current sociocultural changes (e.g. delays in complet-
ing education, occupational attainment, and parenthood) (Patton 
et al. 2018). Among the challenges that adolescents have to face 
are the structuring of a “narrative identity” or self-story, featuring 
the development of a sense of personal identity that integrates 
past experiences with current, and future goals and meanings in 
a coherent whole over time (McAdams and McLean 2013, McLean 
and Lilgendahl 2019). The definition of the new boundaries of 
adolescents’ personal identity involves significant changes in the