Toward a third wave of transdiagnostic psychological therapies: Commentary on Caspi et al. (2026)

Caspi et al. (see record 2026-80066-001) present compelling data that individuals who suffer from mental ill health rarely experience only one diagnosable psychiatric disorder across their life course, but in fact are much more likely to have a unique and fluid mental disorder life history-so-called "heterotypic continuity." Caspi et al. present new analyses from the seminal Dunedin Study showing that by midlife (age 45), an overwhelming majority of individuals (85%) who have experienced any mental health condition had in fact experienced comorbid diagnoses, with nearly all diagnoses predicting subsequent disorders that cut across diagnostic families (internalizing disorders, externalizing disorders, and thought disorders; see also Caspi et al., 2020). Similarly, they present new analyses from the Danish national register data (building on Plana-Ripoll et al., 2019), which demonstrate that receiving a diagnosis of one mental disorder is associated with a persistently elevated risk (for at least 15 years) of subsequently developing all other major mental disorders. (PsycInfo Database Record (c) 2026 APA, all rights reserved).