## 3 Results  
Descriptive statistics revealed an uneven distribution of adolescent girls and boys among the participants, with 70.28% being girls and 29.72% boys. Within the groups, four boys (25%) were assigned to the control group and seven boys (31%) to the experimental group. [PERSON]'s exact test was used to evaluate the sex distribution across groups, as the Chi-square test of homogeneity was not performed due to insufficient sample size, consistent with prior recommendations [59]. The results indicated no statistically significant difference in sex distribution between the control and experimental groups (\(p=0.237\)). Participants' ages ranged from 12 to 14 years (Mage = 12.51 years, SD = 0.43). An independent sample \(t\)-test showed no significant difference in age between the two groups (MD = 0.13 years, \(t(26)=0.994\), \(p=0.327\)). Regarding parental marital status, most participants (75.8%) reported that their parents were either married or cohabiting, while 12.1% had separated parents, and another 12.1% had divorced parents. Independent-samples t-test or Mann-Whitney \(U\) tests showed that there were no significant differences between the groups at baseline in any of the study measures (\(p>0.05\); see Table 1). The mean and standard deviations of primary and secondary measures of the study are reported in Table 1.  
ER measures: As could be revised in Table 2, mixed ANOVA analyses did not show statistically significant interactions (\(p>0.05\)) between group and assessment time in any of the ER measures. However, there were statistically significant main effects of assessment time (\(p<0.05\)) in emotional control, assessed by the BRIEF-2 self-report and in ruminative symptoms, as assessed by the RRS. Overall, there was a reduction in the scores of both maladaptive ER skills on both groups, from pre- to post-assessment (see Figure 2A,B), while no significant main effects of time (\(p>0.05\)) were observed in other maladaptive ER measures (i.e., emotional suppression) or adaptative ER strategies (i.e., cognitive reappraisal). Mental health measures: Mixed ANOVA analyses revealed significant interactions (\(p<0.05\)) between group and assessment time for depressive symptoms. A marginally significant interaction was also found for global internalizing symptoms (\(p=0.054\)), as shown in Table 2. To explore these findings further, follow-up analyses were conducted to compare pre- and post-intervention differences within each group. These analyses provided mean differences (\(MD\)) and standard errors (\(SE\)) to quantify the changes observed. The results showed that the experimental group experienced significant improvements: their internalizing symptoms decreased (\(MD=11.90\), \(SE=2.99\), \(p=0.001\)) and their depressive symptoms also decreased (\(MD=3.09\), \(SE=0.95\), \(p=0.003\)) from pre- to post-intervention. In contrast, the control group showed no significant changes in either internalizing or depressive symptoms from pre- to post-intervention, as shown in Figure 2C,D. These findings suggest that the experimental intervention was effective in reducing both internalizing and depressive symptoms, whereas the control group did not show such improvements.