Conceptual challenges in psychiatric nosology: ADHD across six editions of the DSM

Recent initiatives by the American Psychiatric Association to revise the DSM reflect renewed efforts to address enduring challenges in psychiatric nosology (e.g. absence of clear biological markers, substantial heterogeneity within disorders and high comorbidity across disorders). This article examines five key classification challenges emerging from successive diagnostic revisions in one of the most common childhood diagnoses: attention-deficit hyperactivity disorder (ADHD). Importantly, this theoretical analysis is anchored in prior empirical findings from a systematic textual analysis of all DSM descriptions related to ADHD, from DSM-III (1980) to DSM-5-TR (2022). Drawing on foundational principles from the philosophy of science, the analysis examines how diagnostic adjustments introduced in response to empirical findings or clinical concerns may carry broader implications for the structure, boundaries and conceptual coherence of psychiatric diagnosis. These include: (a) prevalence and the threshold of deviance; (b) gender and diagnostic heterogeneity; (c) aetiological framing and explanatory coherence; (d) medical framing and diagnostic boundaries; and (e) comorbidity and discriminant validity. Addressing these challenges, as well as the broader epistemic foundations of psychiatric diagnosis discussed in this article, may benefit clinicians facing complex diagnostic decisions in everyday practice and theorists developing future psychiatric classification systems.