Developmental Pathway in Psychopathology: The Emerging Field of Transition Psychiatry

Over recent decades, psychopathology has progressively shifted from a static, categorical framework toward a developmental and lifespan-oriented perspective. Within this paradigm, transitional phases across the life course have been recognized as critical windows of vulnerability for the onset, transformation, or exacerbation of mental disorders. This narrative review outlines the conceptual foundations and clinical relevance of transition psychiatry, an emerging field that integrates developmental psychopathology with the study of psychosocial and biological transitions. Drawing on classical developmental theories and contemporary models of continuity and discontinuity, we examine how deviations from normative developmental trajectories may lead to heterogeneous psychopathological outcomes. Particular attention is devoted to highrisk transitions, including the perinatal period and the transition from adolescence to adulthood, during which neurobiological maturation, psychological reorganization, and changing social demands converge. Evidence from perinatal psychiatry, clinical high-risk states for psychosis, and neurodevelopmental disorders, specifically autism spectrum disorder and attention-deficit/hyperactivity disorder, is discussed to illustrate how symptom expression, functional impairment, and comorbidity patterns evolve across transitions. We highlight that many psychiatric conditions originate early in life but manifest clinically in a dynamic and context-dependent manner, with transitional stressors acting as catalysts rather than sole causes of psychopathology. In this framework, transition psychiatry offers a process-oriented approach that moves beyond age-bound diagnoses, emphasizing prevention, early intervention, and developmentally sensitive mental health care across the lifespan.