i-STAIR specifically targets emotion dysregulation and poor interpersonal skills. i-STAIR comprises eight sessions (one hour per session, per week) and each session focuses on a particular skills deficit. In general, session-by-session topics include: (1) labelling and identifying feelings; (2) emotion management (i.e., focus on anger and anxiety); (3) distress tolerance; (4) acceptance of feelings and enhanced experiencing of positive emotions; (5) identification of trauma-based interpersonal schemas and their enactment in day-to-day life; (6) identification of conflict between trauma-generated feelings and current interpersonal goals; (7) role plays related to issues of power and control; and (8) role plays related to developing flexibility in interpersonal situations involving power differentials.

Online general psychoeducation comprises five online sessions (one hour per session on Week 1, Week 2, Week 4, Week 6, and Week 8) where a trained research staff will provide psychoeducation to the participant for up to 1 hour, as well as three weeks of self-guided activities where the participant will work on a specific activity on their own and feedback will be provided during the online sessions. The online psychoeducation content will focus on the link between adverse childhood experiences and depression, and healthy lifestyle changes including healthy diet, exercise, and sleep.

Internet-Delivered Skills Training in Affective and Interpersonal Regulation (i-STAIR) is a psychological intervention that is focused on applying skills to improve emotion regulation difficulties and reduce interpersonal problems over two months (eight sessions; one session per week). i-STAIR also significantly reduces PTSD symptoms without direct discussion of the trauma and may be used alone or adjunctively to boost the effects of trauma-focused therapies.

The PHQ-9 will be used to assess for self-reported depressive symptoms. The PHQ-9 comprises 9 items which are rated on a 4-point Likert scale (ranging from 0=not at all to 3=nearly every day). Higher scores indicate more severe depressive symptoms. The PHQ-9 is used in the local clinical setting for routine screening of depressive symptoms.

The DERS-S will be used to assess for global emotion dysregulation. Global emotion dysregulation comprises 6 dimensions: non-acceptance of emotional response, difficulties engaging in goal-directed behavior, impulse control difficulties, lack of emotional awareness, limited access to emotion regulation strategies, and lack of emotional clarity. Higher scores will indicate more severe global emotion dysregulation.

The RRS will be used to measure habitual rumination. Rumination is a prevalent maladaptive emotion regulation strategy among patients with mental disorders and exerts a moderate to strong effect on psychopathology. Higher scores on the RRS will indicate more frequent use of rumination. The RRS demonstrated good psychometric properties in the literature.

The MSPSS will be used to measure an individual's level of perceived social support from three sources: Significant Others, Family and Friends. The MSPSS comprises 12 items and each item is rated on a seven-point Likert-type scale (ranging from 1=Very Strongly Disagree to 7=Very Strongly Agree).

The PCL-5 will be used to assess for self-reported PTSD symptoms. The PCL-5 is self-rated and higher scores indicate more severe PTSD symptoms (total score range from 0 to 80).