ADHD Is Not a Disorder A Rate-Distortion Account of Attention-Deficit/Hyperactivity as Compression-Threshold Variation An Application of Adaptive Compression Advantage Theory (ACAT)

Attention-Deficit/Hyperactivity Disorder (ADHD) is classified as a neurodevelopmental disorder in the DSM-5. This paper argues that this classification is mechanistically unfounded. Applying the Adaptive Compression Advantage Theory (ACAT; Murata, 2026), we propose that ADHD constitutes a low compression-activation threshold—a parametric variation in which the compression function fires in response to all incoming stimuli rather than selectively filtering for task-relevant inputs. This is not a deficit in attention but a surplus in compression initiation. We demonstrate that every DSM-5 criterion for ADHD—inattention, hyperactivity, and impulsivity—derives from a single parameter shift without invoking pathology. Hyperfocus, the most paradoxical ADHD feature, is explained as domain-locked compression when α(d) is sufficiently high in a specific domain to monopolize processing resources. We reinterpret the mechanism of action of methylphenidate and amphetamines as compression-reward recalibration rather than dopamine deficit correction, explain the ADHD–creativity link as a structural consequence of low-threshold compression, and derive why ADHD is adaptive in information-rich environments but maladaptive in environments requiring sustained verbatim processing. The framework generates eleven testable predictions and argues that the categorical diagnosis of ADHD should be replaced by continuous measurement of the compression-activation threshold θ_c, a parameter that varies across the population with no natural discontinuity separating “disordered” from “normal.” Keywords: ADHD, rate-distortion theory, compression threshold, hyperfocus, methylphenidate, creativity, cognitive architecture, attention, dopamine, ACAT, neurodiversity, executive function