Background
Due to the inclusion of nonsuicidal self-injury (NSSI) in the Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5) [
1] as a research diagnosis in section III, further studies are needed to enable a better understanding of this behavior. Independent of classification discussions, high prevalence and comorbidity rates [
2‐
4], low quality of life [
5], and increased risk of suicidality [
6] highlight the importance of further research on NSSI. Special attention should be paid to adolescents, as NSSI often has its onset during this time [
4,
7]. Previously, NSSI was generally assessed as one of the nine symptoms of Borderline Personality Disorder (BPD), however only a minority of adolescents with NSSI suffer from BPD [
5,
8]. Several differences in the phenomenology and functions of NSSI can be found between patients with NSSI and BPD (NSSI + BPD) and patients with NSSI without BPD (NSSI − BPD). Patients with NSSI + BPD show more frequent and severe NSSI, greater diagnostic comorbidity, more severe depressive symptomatology, suicidal ideation, and emotion dysregulation than patients with NSSI − BPD [
9,
10]. Regarding functions of NSSI, adolescents with NSSI + BPD endorsed higher self-punishment, anti-suicide, and anti-dissociation functions of NSSI than adolescents with NSSI − BPD [
11].
Among different personality concepts, Cloninger´s [
12,
13] biopsychosocial personality model seems to be able to describe healthy as well as pathological temperament and character traits, and to differentiate between patients with and without personality disorders [
14,
15]. The extended model [
13] includes four temperament dimensions (novelty seeking, harm avoidance, reward dependence, persistence) and three character dimensions (self-directedness, cooperativeness, self-transcendence), see Table
1. Low levels of self-directedness and cooperativeness are characteristics for personality disorders [
16].
Table 1
Temperament and character dimensions
Temperament
|
Novelty seeking | Curious, impulsive, sensation seeking | Indifferent, thoughtful, modest |
Harm avoidance | Worried, pessimistic, frightened, shy | Relaxed, optimistic, fearless, confident, talkative |
Reward dependence | Sensitive, warm, dependent | Cold, secluded, independent |
Persistence | Hard-working, ambitious, perfectionist | Inactive, lethargic, pragmatic |
Character
|
Self-directedness | Mature, effective, responsible, determined, high self-acceptance | Immature, unreliable, indecisive, low self-acceptance |
Cooperativeness | Social tolerant, empathic, helpful | Social intolerant, critical, cold, not helpful, destructive |
Self-transcendence | Experienced, patient, creative, self-forgetting, connected to the universe, spiritual | Uncomprehending, proud, unimaginative, lack of humility |
Patients with BPD often show a temperament profile consisting of both high harm avoidance and novelty seeking [
14,
16‐
18]. According to Cloninger, Praybeck, Svrakic, and Wetzel [
19], a personality pattern consisting of high novelty seeking and high harm avoidance represents an approach-avoidance conflict that may cause affective instability, a core feature of BPD. Studies of adolescents with NSSI − BPD are needed to investigate the link between NSSI and the described personality pattern, especially high novelty seeking and harm avoidance. Indeed, higher levels of novelty seeking were found in adolescents with NSSI compared to adolescents without NSSI [
20]. Furthermore, adolescents with depressive disorder and self-harm behavior reported more harm avoidance than those without self-harm [
21].
Low self-directedness is related to self-injurious behavior in adolescents [
20,
21], BPD in adolescents [
18] and BPD in adults [
14]. Higher levels of cooperativeness were found in female adolescents with self-harm behavior (self-injuring behavior including suicidal behavior) compared to those without self-harm behavior [
22], whereas adults with BPD showed lower levels of cooperativeness than adult controls [
14]. Ohmann et al. [
22] offer the explanation that higher cooperativeness levels in adolescents with self-harm behavior may be related to pronounced helplessness. High self-transcendence is linked to NSSI in adolescents [
20] and to BPD in adults [
14]. Low reward dependence is linked to internalizing symptoms like depression and anxiety [
23], but no association has been found between reward dependence and NSSI [
20], nor between reward dependence and self-harm behavior [
21,
22]. Kaess et al. [
18] found lower reward dependence in adolescents with BPD than in clinical and healthy controls. Further, persistence is linked neither to BPD [
14,
18] nor to NSSI [
20] or self-harm behavior.
In summary, for BPD, most studies support the personality pattern suggested by Cloninger et al. [
16,
19], consisting of high novelty seeking and harm avoidance as well as low levels of self-directedness and cooperativeness [
14,
18]. Adolescents with NSSI show a similar personality pattern to adolescents with BPD, however most studies have not controlled for comorbid BPD [e.g. 20, 21]. Studies using the big five model found similar personality traits related to self-injurious behavior, namely high neuroticism (comparable to harm avoidance), low agreeableness (comparable to cooperativeness), and low conscientiousness (comparable to self-directedness and persistence) [
24,
25]. One part of novelty seeking, impulsivity, might explain the difficulties self-injurers have with resisting the urge to injure themselves [
26]. NSSI itself is often an impulsive act, as most of the individuals with NSSI think about the act for less than five minutes before committing it [
27]. Indeed, on self-report measures individuals with NSSI indicated higher impulsivity than individuals without NSSI [
26,
28,
29], and patients with repetitive self-harm reported even higher impulsivity than patients with onetime self-harm behavior [
30]. However, previous research has found low convergence between self-report and behavioral measures of impulsivity [for a meta-analysis see [
31].
Response inhibition, one aspect of impulsivity, can be measured with a Go/NoGo task. Janis and Nock [
29] compared self-reported impulsivity with experimentally assessed impulsivity in adolescents with NSSI. While participants with NSSI scored higher on self-reported impulsivity, they did not differ from the mixed clinical and nonclinical comparison groups without NSSI on behavioral measures. This result has been replicated in studies of adults with NSSI [
26,
32]. The difference between self-reported and experimentally assessed impulsivity may be explained by the measurement of different impulsivity constructs. While self-report questionnaires measure general response tendencies (traits), behavioral tasks may in fact measure spontaneous reactions that are influenced by current cognitive processes [
32]. Therefore, it seems important not only to investigate impulsivity with self-report measures, but also with behavioral tasks.
In summary, previous research is consistent with the notion that certain temperament traits underlie features of BPD symptoms. However, it remains unclear, if the same pattern can be found in a sample of adolescents with NSSI disorder without BPD. None of the presented studies assessed self-injuring behavior according to the
DSM-
5 criteria [e.g.
20‐
22]; whereas Hefti et al. [
20] investigated a school sample, Joyce et al. [
21] investigated depressed adolescents with and without self-harm behavior, and Ohmann et al. [
22] investigated adolescents presenting at in- and outpatient clinics. Thus, the samples were heterogeneous. To our knowledge, no study has investigated Cloninger’s temperament and character traits in adolescents with NSSI disorder with and without BPD. Cloninger’s personality traits might be especially suitable for the distinction between adolescents with and without BPD because of its dimensional structure. Therefore, the aim of the present study was to investigate impulsivity (self-report and a behavioral measures), temperament and character traits in adolescents with NSSI disorder (according to DSM-5), and differences in personality dimensions according to Cloninger et al. [
13] between adolescents with NSSI with and without comorbid BPD.
We hypothesized that there are dimensional differences in temperament and character traits between four groups of adolescents. Specifically, we addressed the following research questions.
1.
Do adolescents with NSSI disorder show a different personality pattern in comparison to the clinical control (CC) and the nonclinical control (NC) groups? Taking the results of previous studies into account, we hypothesized that adolescents with NSSI disorder would show higher values on novelty seeking, self-transcendence, and harm avoidance as well as lower values on self-directedness compared to the NC and the CC groups.
2.
Do adolescents with NSSI + BPD show a distinct personality pattern in comparison to adolescents with NSSI − BPD? To our knowledge, no other studies exist, and therefore this analysis was exploratory.
3.
Do adolescents with NSSI − BPD report more impulsivity than the NC and the CC groups? Is this difference evident in an emotional Go/NoGo task? Because of the heterogeneous results of previous studies, this analysis was also exploratory.
Discussion
The aim of the present study was to investigate temperament and character traits on the basis of Cloninger's [
12,
13] personality model, with a special focus on impulsivity in adolescents with NSSI disorder without BPD (NSSI − BPD), adolescents with NSSI disorder and BPD (NSSI + BPD), a clinical control group, and a nonclinical control group. As expected, the groups showed distinct personality profiles. The JTCI scales as well as most YSR scales indicate a staircase-like appearance ranging from nonclinical adolescents to adolescents with NSSI + BPD. Adolescents with NSSI disorder without BPD scored higher on novelty seeking and harm avoidance and lower on self-directedness, persistence and cooperativeness than clinical controls. In adolescents with NSSI + BPD this personality pattern was even more pronounced than in adolescents with NSSI − BPD. Thus, we were able to replicate the personality pattern consisting of high harm avoidance and novelty seeking in adolescents with NSSI + BPD, similar to Cloninger [
16] and Kaess et al. [
18]. The approach-avoidance conflict generated from this pattern might be a reason for the emotional instability patients with BPD experience [
19]. In addition, we extended these findings to adolescents with NSSI disorder without BPD. In these patients, the personality pattern described above was less pronounced. Nevertheless, the harm avoidance score above cut off indicates that adolescents with NSSI − BPD are more careful, fearful, insecure, and negativistic than the adolescents from the CC and the NC groups. Adolescents with NSSI − BPD differed from adolescents with NSSI + BPD regarding psychopathology and partially in borderline symptomatology but nevertheless showed a similar personality pattern to adolescents with NSSI + BPD. This result underlines the need for a dimensional personality assessment to better understand adolescents with NSSI − BPD. Further research should focus on maladaptive personality traits that do not constitute a formal personality disorder and on the validation of the dimensional personality model suggested in section III of the
DSM-
5.
Results of the present study replicated a profile of lower levels of self-directedness in adolescents with NSSI (−BPD and +BPD) than adolescents without NSSI, similar to Hefti et al. [
20] and Joyce et al. [
21]. In contrast to Ohmann et al. [
22], we found lower levels of cooperativeness in adolescents with NSSI compared to adolescents without NSSI, however this result is similar to the low level of cooperativeness found in adolescents with BPD [
53]. Lower cooperativeness may cause more interpersonal conflict and distress through socially intolerant, critical, and destructive conflict behavior. In fact, previous research indicates that adolescents with NSSI frequently report problems in social interactions [
54] that can trigger NSSI [
55]. Compared to the CC group, the level of persistence in adolescents with NSSI was low but still in the normal range. Previous studies have shown that adolescents with NSSI give up faster when pursuing goals, while adolescents without NSSI are more diligent and persevering [
40]. All groups were similar regarding self-transcendence, therefore, we could not find supporting evidence for a higher self-transcendence as previously reported in adolescents with NSSI [
20] and adults with BPD [
14]. This may be explained by differences in the study populations (school sample vs. clinical sample, female vs. male adolescents, adolescents vs. adults and NSSI vs. BPD).
To summarize, there was a significant difference in temperament and character traits between adolescents with NSSI + BPD and adolescents with NSSI − BPD, despite the small NSSI + BPD sample size (
n = 14). Compared to the other groups, the NSSI − BPD group displayed higher standard deviations on the subscales of the JTCI, indicating the heterogeneity of this group. Considerable diagnostic heterogeneity among adolescents with NSSI has been described in earlier studies [
2].
Adolescents with NSSI disorder (−BPD and +BPD) showed more novelty seeking than the CC group as well as higher scores on all subscales of the Barratt Impulsiveness Scale (attentional, non-planning, and motor impulsivity). However, this difference was not evident in the Go/NoGo task with neither a group effect, nor an emotion effect emerging. Happy faces were associated with faster reactions and a lower error rate compared to angry faces, indicating that happy faces are easier to discern than angry faces. Our results are in line with several other studies that indicated more self-reported impulsivity in adolescents [
26,
29] and adults with NSSI [
32], but failed to show this difference on behavioral measures. This leaves the question open, as to whether adolescents with NSSI perceive themselves as more impulsive than they actually are. However, this discrepancy between self-report and behavioral measures is not only observed in adolescents with NSSI, but also represents a general difficulty in the measurement of impulsivity that may be explained by the measurement of different impulsivity constructs [
32]. It remains to be investigated, if the difference between self-reported and experimentally assessed impulsivity can be explained by the measurement of different impulsivity constructs, or if adolescents with NSSI are able to suppress their impulsivity for an experimental task. Adolescents with NSSI + BPD reported even more impulsivity than adolescents with NSSI − BPD, especially more non-planning impulsivity (lack of future orientation and foresight). Highly impulsive individuals may be especially motivated to act rashly in the context of negative emotions because long-term benefits become less important compared to short-term gains of emotion regulation, e.g. The Theory of Urgency [
56], also see [
57]. Therefore, individuals with high levels of non-planning impulsivity may be highly motivated to obtain the immediate benefits of NSSI (e.g., relief of negative emotions) with less concern for the long-term consequences of NSSI. There was no significant difference between adolescents with NSSI + BPD and with NSSI − BPD in the Go/NoGo task.
The results of the present study should be interpreted in the context of some limitations. The design of the study was cross-sectional. Therefore, the current study cannot explain whether certain temperament and character traits might favor the development of NSSI. This should be investigated in future prospective longitudinal studies. Nevertheless, results indicate an association between temperament and character traits and NSSI disorder. Due to the small sample sizes of adolescents with BPD, comorbidity with other personality disorders could not be included in the analyses. The recommendation of the
DSM-
5 is to apply a diagnosis of a personality disorder in children and adolescents when maladaptive personality traits appear to be pervasive, persistent, unlikely to be limited to a particular developmental stage or another mental disorder, and after one year of persistent symptoms. Given the mean age of the participants under 16 years of age, we were careful applying a diagnosis of a personality disorder. However, despite the small NSSI + BPD sample size, significant differences emerged between adolescents with NSSI + BPD and adolescents with NSSI − BPD. The high prevalence of NSSI in inpatient samples (50%) [
9] represented a challenge for the recruitment of a clinical inpatient sample without NSSI. Our sample consisted of female adolescents admitted to a psychiatric unit and therefore generalizations to male outpatients must be made with caution. Regarding the Go/NoGo task, the low error rate indicates that the response pressure was too low. Therefore, future studies should use a higher ratio of Go stimuli to NoGo stimuli.
A strength of this study was the use of the DSM-5 diagnostic criteria for NSSI disorder in a clinical sample. In addition, a clinical control group of adolescents with other mental disorders without NSSI was included. This allowed us to identify temperament and character traits specific to NSSI disorder with and without BPD. To our knowledge, this is the first study comparing temperament and character traits in adolescents with NSSI + BPD and adolescents with NSSI − BPD in an inpatient setting. In addition to self-report measures, impulsivity was assessed using an experimental task.
Authors’ contributions
TT and CR completed the data analyses and made substantial contributions to the interpretation of the data, the drafting, and the revision of the manuscript. TI and MS contributed to the ideas, the acquisition and interpretation of the data, the drafting and the revision of the manuscript. All authors read and approved the final manuscript.