Abstract
This case study investigates the complex interplay between autism spectrum disorder (ASD) and maladaptive daydreaming (MD), focusing on the misinterpretation of stereotypical movements. The case investigates Liam, a 23-year-old male diagnosed with ASD in childhood. He sought reassessment due to suspicions that his "stimming" behaviors might be linked to MD rather than autism. We analyze Liam's freely reported experiences, self-reported scale scores, and the outcome of clinician-administered diagnostic interviews scored independently by two clinicians. Findings reveal that social communication problems were not present, negating the diagnosis of ASD, and behaviors previously attributed to ASD could be better construed as kinesthetic components of MD episodes. This case highlights the potential for misidentification of MD as ASD, mainly when stereotypical movements are present. The case study underscores the significance of awareness to MD in research and clinical settings. It also illuminates the critical importance of differential diagnosis in cases of ASD, as similar behavioral manifestations may stem from distinct underlying conditions. This study contributes to the emerging body of literature on the relationship between ASD and MD and calls for increased awareness among clinicians about the potential overlap in symptoms between these conditions. We discuss future research directions and implications for clinical practice.