Autism spectrum disorder features drove obsessive cannabis use and extreme food restriction in a young man

A 26-year-old man with long-standing ASD developed a pattern of obsessive alcohol use associated with weight gain, followed by extreme food restriction, then transition to near-constant daily cannabis use. This culminated in a hospitalization for depression and suicidal ideation after a cannabis-related car accident. His BMI declined from 23.6 to 16.98 over one year. Over 11 days of inpatient treatment with anxiolytics, antidepressants, sleep aids, cannabis withdrawal management, and nutritional rehabilitation, his BMI improved to 18.75.

Single case report documenting clinical presentation, diagnostic assessment, multidisciplinary inpatient treatment, and discharge planning for co-occurring ASD, substance use disorder, and eating disorder.

ASD traits like obsessive fixation and cognitive rigidity are well-documented but rarely discussed as drivers of substance use patterns. This case illustrates how the same neurodevelopmental features that define ASD can channel into harmful behaviors, requiring integrated treatment approaches rather than siloed addiction or eating disorder care.

The co-occurrence of ASD, substance use, and eating disorders is increasingly recognized but treatment systems remain fragmented. This case demonstrates why integrated care models that address the underlying neurodevelopmental features driving multiple conditions simultaneously are needed.

Single case report cannot establish generalizable patterns. Complex presentation makes it difficult to isolate the role of cannabis specifically. Self-reported history may not capture the full timeline of substance use and behavioral changes.