Symptom course in psychiatric and neurodevelopmental diagnostic reasoning: an exploratory vignette-based study

Background. According to DSM-based diagnostic principles, psychiatric and neurodevelopmental diagnoses rely on symptom specificity (i.e., excluding alternative explanatory disorders) and on a conceptual separation between the diagnostic category and its potential underlying medical causes. In clinical practice, however, clinicians may also consider whether symptoms persist or resolve over time when deciding whether to retain a diagnosis. We examined whether clinicians take into account the longitudinal course of symptoms, including persistence and reversibility, when making diagnostic decisions. Methods. Twenty-seven French health professionals (13 psychiatrists and 14 non-medical clinicians) evaluated six clinical vignettes describing psychiatric or neurodevelopmental symptoms occurring in the context of underlying medical conditions, sensory impairments, or co-occurring disorders. Across vignettes, symptom trajectories differed: in some cases, symptoms resolved rapidly after treatment of the associated condition, whereas in others they followed a typical and persistent course. Clinicians indicated whether symptoms should be attributed solely to the associated condition or whether both diagnoses should be retained. Results. Clinicians’ diagnostic decisions strongly depended on symptom evolution. When symptoms resolved rapidly after treatment (suggesting an abnormally favorable clinical course) clinicians predominantly attributed the presentation to the underlying condition alone (77.8–92.6%). This pattern was observed for ADHD-like symptoms associated with obstructive sleep apnea, language difficulties associated with hearing loss, and psychotic symptoms associated with anti-NMDAr encephalitis. In contrast, when symptoms followed a typical and persistent trajectory, clinicians largely maintained dual diagnoses (81.5–96.3%), as illustrated by schizophrenia associated with 22q11 microdeletion, ASD associated with SHANK3 mutations, and intellectual disability associated with fetal alcohol syndrome. Conclusions. These findings suggest that the described course of symptoms may influence clinicians’ diagnostic judgments in complex cases, although further research is needed to clarify how symptom trajectories are used in real-world clinical reasoning.