Special Issue: Using Temperament to Understand Risk and Variation in Mental Illness

Temperament refers to early-emerging differences in emotion and behavior that are relatively stable and tied to biological processes. The September 2026 special issue of Clinical Psychological Science collects 10 articles that use temperament-based approaches to tackle two practical problems clinicians and researchers face: predicting who is at risk for mental disorders, and explaining why people with the same diagnosis can look or respond very differently. What the collection does differently The papers move beyond single-level descriptions. Several studies link infant and toddler temperament to later clinical outcomes. Others combine temperament measurement with brain data or observations of parent–child interaction. A deliberate focus on longitudinal methods provides tests of prediction over extended time windows rather than cross-sectional snapshots. Representative studies and approaches

• Toddler temperament and neurodevelopmental disorders: Girija Kadlaskar and colleagues at the MIND Institute examine how individual differences in toddler temperament contribute to risk for autism spectrum disorder and ADHD. Their work treats temperament as an early marker that helps differentiate developmental pathways.
• Temperament profiles within diagnoses: Michael Kozlowski and coauthors present temperament-based profiles that explain variation within existing diagnostic categories. This approach aims to capture meaningful subgroups that standard categories miss.
• Neural features plus parenting: Joscelin Rocha-Hidalgo and colleagues link temperament to neural signatures and consider how parent–child interactions modify those links. That combination clarifies mechanisms through which temperament manifests as symptom patterns.

What this implies for practice and research

• Assessment: Temperament measures added to diagnostic assessment can provide early risk signals and point to individualized intervention targets.
• Heterogeneity within diagnoses: Recognizing temperament profiles helps explain why two patients with the same diagnostic label may need different treatment approaches.
• Multi-level monitoring: Combining behavioral, neural, and contextual data strengthens causal inferences about pathways to disorder and resilience.
• Developmental timing: Longer follow-up periods yield clearer prediction and show how early temperament interacts with later experiences such as adversity and parenting.

The special issue demonstrates that temperament-based frameworks—measured early and tracked across time, and combined with biological and contextual data—offer practical advances for predicting risk, parsing heterogeneity, and guiding more tailored approaches to prevention and treatment of mental disorders.