In The Politics of Autism, I discuss various ideas about what causes the condition. Studies have ruled out vaccines as a cause of autism, but there is a very long and growing list of other correlates, risk factors, and possible causes that have been the subject of serious studies. This blog has identified at least 41 such items. Cannabis is one of them.
Background: It is plausible that exposure to cannabis in-utero could be associated with an increased risk of neurodevelopmental disorders such as attention deficit hyperactivity disorder (ADHD) symptoms and autism spectrum disorder (ASD) during childhood and adolescence; however, mixed results have been reported. This study investigated whether there is an association between prenatal cannabis use and ADHD symptoms and ASD in offspring using a systematic review and meta-analysis methodology.
Methods: A systematic literature search was conducted in PubMed/Medline, Scopus, EMBASE, Web of Science, Psych-Info, and Google Scholar to identify relevant studies. The study protocol has been preregistered in the Prospective Register of Systematic Reviews (PROSPERO) (CRD42022345001), and the Newcastle-Ottawa Quality Assessment Scale (NOS) was used to assess the methodological quality of included studies. An inverse variance weighted random effect meta-analysis was conducted to pool the overall effect estimates from the included studies.
Results: Fourteen primary studies, consisting of ten on ADHD and four on ASD, with a total of 203,783 participants, were included in this study. Our meta-analysis underscores an increased risk of ADHD symptoms and/or disorder [β = 0.39: 95 % CI (0.20-0.58), I2 = 66.85 %, P = 0.001)] and ASD [RR = 1.30: 95 % CI (1.03-1.64), I2 = 45.5 %, P = 0.14] associated with in-utero cannabis exposure in offspring compared to their non-exposed counterparts. Additionally, our stratified analysis highlighted an elevated risk of ADHD symptoms [β = 0.54: 95 % CI (0.26-0.82)] and a marginally significant increase in the risk of diagnostic ADHD among exposed offspring compared to non-exposed counterparts [RR = 1.13, 95 % CI (1.01, 1.26)].
Conclusion: This study indicated that maternal prenatal cannabis exposure is associated with a higher risk of ADHD symptoms and ASD in offspring.
Keywords: ADHD; ASD; Cannabis; Marijuana; Neurodevelopmental disorders; Offspring; Pregnancy; Prenatal.
