Non-suicidal self-injury (NSSI) is associated with mental disorders, yet work regarding the direction of this association is inconsistent. We examined the prevalence, comorbidity, time–order associations with mental disorders, and sex differences in sporadic and repetitive NSSI among emerging adults.

We used survey data from n = 72,288 first-year college students as part of the World Mental Health-International College Student Survey Initiative (WMH-ICS) to explore time–order associations between onset of NSSI and mental disorders, based on retrospective age-of-onset reports using discrete-time survival models. We distinguished between sporadic (1–5 lifetime episodes) and repetitive (≥6 lifetime episodes) NSSI in relation to DSM-5 mood, anxiety, and externalizing disorders.

We estimated a lifetime NSSI rate of 24.5%, with approximately half reporting sporadic NSSI and half repetitive NSSI. The time–order associations between onset of NSSI and mental disorders were bidirectional, but mental disorders were stronger predictors of the onset of NSSI (median RR = 1.94) than vice versa (median RR = 1.58). These associations were stronger among individuals engaging in repetitive rather than sporadic NSSI. While associations between NSSI and mental disorders generally did not differ by sex, repetitive NSSI was a stronger predictor for the onset of subsequent substance use disorders among females compared to males. Most mental disorders marginally increased the risk for persistent repetitive NSSI (median RR = 1.23).

Our findings offer unique insights into the temporal order between NSSI and mental disorders. Further work exploring the mechanism underlying these associations will pave the way for early identification and intervention of both NSSI and mental disorders.

Dietary interventions did not prevent depression onset nor reduced depressive symptoms in a large multi-center randomized controlled depression prevention study (MooDFOOD) involving overweight adults with subsyndromal depressive symptoms. We conducted follow-up analyses to investigate whether dietary interventions differ in their effects on depressive symptom profiles (mood/cognition; somatic; atypical, energy-related).

Baseline, 3-, 6-, and 12-month follow-up data from MooDFOOD were used (n = 933). Participants received (1) placebo supplements, (2) food-related behavioral activation (F-BA) therapy with placebo supplements, (3) multi-nutrient supplements (omega-3 fatty acids and a multi-vitamin), or (4) F-BA therapy with multi-nutrient supplements. Depressive symptom profiles were based on the Inventory of Depressive Symptomatology.

F-BA therapy was significantly associated with decreased severity of the somatic (B = −0.03, p = 0.014, d = −0.10) and energy-related (B = −0.08, p = 0.001, d = −0.13), but not with the mood/cognition symptom profile, whereas multi-nutrient supplementation was significantly associated with increased severity of the mood/cognition (B = 0.05, p = 0.022, d = 0.09) and the energy-related (B = 0.07, p = 0.002, d = 0.12) but not with the somatic symptom profile.

Differentiating depressive symptom profiles indicated that food-related behavioral interventions are most beneficial to alleviate somatic symptoms and symptoms of the atypical, energy-related profile linked to an immuno-metabolic form of depression, although effect sizes were small. Multi-nutrient supplements are not indicated to reduce depressive symptom profiles. These findings show that attention to clinical heterogeneity in depression is of importance when studying dietary interventions.

There is controversy about whether psychotherapies are effective in the treatment of subclinical depression, defined by clinically relevant depressive symptoms in the absence of a major depressive disorder.

To examine whether psychotherapies are effective in reducing depressive symptoms, reduce the risk of developing major depressive disorder and have comparable effects to psychological treatment of major depression.

We conducted a meta-analysis of 18 studies comparing a psychological treatment of subclinical depression with a control group.

The target groups, therapies and characteristics of the included studies differed considerably from each other, and the quality of many studies was not optimal. Psychotherapies did have a small to moderate effect on depressive symptoms against care as usual at the post-test assessment (g = 0.35, 95% CI 0.23–0.47; NNT = 5, 95% CI 4–8) and significantly reduced the incidence of major depressive episodes at 6 months (RR = 0.61) and possibly at 12 months (RR = 0.74). The effects were significantly smaller than those of psychotherapy for major depressive disorder and could be accounted for by non-specific effects of treatment.

Psychotherapy may be effective in the treatment of subclinical depression and reduce the incidence of major depression, but more high-quality research is needed.