Epidemiological Associations of Various Substances and Multiple Cannabinoids with Autism in USA

Abstract

Introduction: Autistic Spectrum Disorder (ASD) is increasing in across USA. Paediatricians and physicians in both Colorado and Australia continue to see high caseloads however this prevalence uptick remains largely unexplained. Since drug use is an obvious potential source of developmental brain damage the present study was undertaken to study drug-ASD associations at state level. Methods: Existing datasets from the US Department of Education Individuals with Disabilities Act, the Substance Abuse and Mental Health Services Administration National Survey of Drug Use and Health, and the Drug Enforcement Agency cannabinoid concentration in seizures were re-analyzed. Results: ASD rates are high and rising fastest in Colorado, Maine, Massachusetts, Oregon, Rhode Island and New Jersey but falling in Oklahoma and Iowa. When the nine highest cannabis use states are grouped together ASD is rising significantly faster there than elsewhere (time:status interaction in quadratic mixed effects model p<0.0001). On univariate regression ASD rate was significantly positively associated with alcohol and cannabis exposure and with the cannabinoids Δ9-tetrahydrocannabinol, cannabinol, cannabichromene, cannabigerol and tetrahydrocannabivarin. These effects remained after multivariate adjustment for Δ9-tetrahydrocannabinol and cannabidiol (from p<0.0001). Cannabidiol correlated with ASD rate when a three year lag was introduced (R=0.7483, p=0.0032). Conclusion: These data show that increased cannabinoid exposure explains on bivariate and multivariate regression much of the recent rise in ASD across USA, and in the context of other reports, also at some local cluster levels. Together with numerous mechanistic reports these data argue for causality and indicate a large case-control study. ASD-like neurobehavioural toxicological syndromes likely represent the commonest form of cannabis-related teratology following peri-gestational exposure.