The research was led by Caitlin M. Prentice of the Department of Psychology at the University of Oslo, together with Stian Orm, Solveig Kirchhofer, Trude Fredriksen, Matteo Botta, Erica Zahl, Torun M. Vatne, and Krister Fjermestad, drawing on data from an ongoing randomised controlled trial of the SIBS program—a manual-based preventive intervention designed to improve parent-sibling communication and sibling mental health in families where a child has a chronic disorder. The team set out to answer a deceptively simple question: which family-level factors predict what teachers report about the mental health of siblings of children with chronic disorders? The design is notable for its multi-informant architecture. Rather than relying solely on the reports of parents or the siblings themselves—the dominant approach in the existing literature—the researchers recruited teachers as independent observers, obtaining Strengths and Difficulties Questionnaire (SDQ) ratings from 127 teachers who knew the children well.

The sample comprised siblings aged 8 to 16 years, with a mean age of 10.3 years and a fairly even gender split of 53.4 percent girls and 46.5 percent boys. Family-level factors were captured through reports from 113 mothers, 85 fathers, and 118 siblings. Families were recruited through healthcare service providers and patient organisations across both rural and urban Norway, a country whose nationalized healthcare system and legal framework explicitly obliges health professionals to support next-of-kin, including siblings, when caring for families with a chronically ill child. Chronic disorders in the study were defined broadly, spanning neurodevelopmental disorders, rare genetic disorders, psychiatric disorders, and somatic illnesses—a deliberate choice reflecting the high level of comorbidity in the sample.

Methodologically, the study leaned on well-validated psychometric instruments. Teacher-rated sibling mental health was measured with the SDQ, a 25-item screening tool in which raters mark statements such as “many worries, often seems worried” as not true, somewhat true, or certainly true. Item scores are summed into subscales—emotional problems, peer problems, conduct problems, and hyperactivity-inattention—which the researchers combined into composite indices of internalizing problems (emotional and peer problems) and externalizing problems (conduct problems and hyperactivity-inattention), a factor structure shown to be appropriate for low-risk populations. Siblings completed the 16-item Negative Adjustment Scale, capturing statements such as “I wish my parents could spend more time with me” and “I feel angry because of my brother or sister’s disability or illness.” Parents rated the emotional and behavioral symptoms of the child with the disorder using the 96-item Developmental Behavior Checklist Primary Carer Version, their own mental health with the Symptom Checklist-90-Revised and the Beck Depression Inventory, and perceived social support with the 18-item Family Support Scale.

The analytical strategy proceeded in two stages. First, bivariate Pearson correlations quantified the raw associations between each family factor and teacher-rated problems. Second, multivariate regression models tested all predictors simultaneously—sibling age and sex, sibling adjustment, symptom severity, parental mental health, family social support, and the age gap between the sibling and the affected child—run separately with mother-reported and father-reported variables, and controlling for sibling age and sex. The significance threshold was set at p ≤ .05, with correlations of 0.10, 0.20, and 0.30 interpreted as weak, moderate, and strong, respectively.

Two findings stood out. Siblings who reported greater difficulty adjusting to living with their brother or sister’s chronic disorder showed moderately higher teacher-rated internalizing problems—the correlation was r = 0.21, statistically significant at p = .023. In parallel, lower father-reported family social support was moderately associated with more teacher-rated externalizing problems, with a correlation of r = −0.24 (p = .029). Crucially, both associations survived the multivariate analyses, in which all factors competed as simultaneous predictors and sibling age and sex were held constant. In the regression models, family factors explained 10 to 12 percent of the variance in teacher-rated externalizing problems—the father-rated model reached an adjusted R² of 0.123—although the models for internalizing problems did not reach overall significance. Being a girl was independently associated with fewer externalizing problems, consistent with gendered patterns of behavior observed in the general population.

Just as instructive were the results that failed to materialize. The severity of emotional and behavioral problems in the child with the chronic disorder, parental mental health, and the age difference between the sibling and the affected child were all unrelated to teacher-rated mental health. The null finding for symptom severity is particularly provocative, because meta-analyses have repeatedly linked greater care-related intrusiveness and higher symptom burden to poorer sibling outcomes. The authors point to a methodological possibility: most previous studies relied on parents—usually mothers—to rate both symptom severity and sibling mental health, creating a risk of common-rater bias that inflates the apparent association. When an independent observer such as a teacher provides the outcome measure, that shared-method inflation disappears, and the true signal may be weaker than previously believed. A similar logic may apply to parental mental health, an otherwise robust predictor of child outcomes even in genetically informed designs, where effects may simply have been too small to detect in a moderately sized sample.

The father-related pattern deserves special emphasis. Father-report data remain rare in child psychopathology research, yet in this study the father-reported variables carried the strongest signal for externalizing problems, and the bivariate correlations between fathers’ own mental health and teacher-rated internalizing problems, though not significant, were in the same range as the sibling adjustment association—while the corresponding maternal correlations were negligible. The authors speculate that fathers may play a distinctive role in siblings’ everyday lives, in part because mothers more often shoulder the bulk of caregiving for the affected child. Previous work has also found that fathers of children with autism rely more on informal than formal support networks and that social support is linked to more effective parenting among fathers of children with developmental disabilities, which could explain why fathers’ perceptions of low family support left a detectable imprint on siblings’ behavior at school.

The clinical implications are direct. Adults, and teachers in particular, are often the gatekeepers who initiate support for children, and the study demonstrates that teachers can perceive when a sibling is struggling—specifically when adjustment to the disorder is poor or family social support is low. This adds quantitative weight to a literature that has largely documented siblings’ feelings of invisibility through qualitative interviews, in which siblings describe withholding negative emotions to avoid burdening their parents and feeling overlooked at home. The Norwegian context may amplify this effect, the authors caution, since Norwegian teachers are trained as social pedagogues with a strong emphasis on children’s social and emotional development, potentially limiting generalizability to systems where academic instruction dominates. The correlational, cross-sectional design also leaves the direction of causality open: low social support might drive disruptive behavior, or a child’s outward difficulties might erode the family’s capacity to attract support. Sample limitations—families predominantly of European ethnicity with above-average parental education, teacher recruitment routed through parents, and no demographic data on the teachers themselves—further counsel caution.

Even with those caveats, the message for practice is clear and actionable. The study strengthens the case for a multi-informant approach to sibling mental health, one in which teachers are treated as legitimate and valuable observers whose perspective complements, rather than duplicates, that of parents. Because siblings frequently describe school as a safe haven—a place where they feel more like their peers and less encumbered by their family situation—the finding that teachers can nonetheless spot the shadow of home-based difficulty suggests a genuine window for early identification. Future research, the authors suggest, should examine additional family factors such as the sibling relationship quality and parenting stress, test the mechanisms linking social support to behavior, gather data on teacher characteristics, and—perhaps most importantly—investigate whether and how teachers act on the perceptions they so evidently form. For the millions of families worldwide raising a child with a chronic disorder, the study offers a quiet reassurance: the sibling in the background is being seen after all.