Abstract
Autism Spectrum Disorder (ASD) is characterized by persistent deficits in social communication and restrictive behavior, interests, and activities. Our previous case-control study showed that use of acetaminophen at age 12-18 months is associated with increased likelihood for ASD (OR 8.37, 95% CI 2.08-33.7). In this study, we again show that acetaminophen use is associated with ASD (p = 0.013). Because these children are older than in our first study, the association is reversed; fewer children with ASD vs. non-ASD children use acetaminophen as a "first choice" compared to "never use" (OR 0.165, 95% CI 0.045, 0.599). We found significantly more children with ASD vs. non- ASD children change to the use of ibuprofen when acetaminophen is not effective at reducing fever (p = 0.033) and theorize this change in use is due to endocannabinoid system dysfunction. We also found that children with ASD vs. non-ASD children are significantly more likely to show an increase in sociability when they have a fever (p = 0.037) and theorize that this increase is due to anandamide activation of the endocannabinoid system in ASD children with low endocannabinoid tone from early acetaminophen use. In light of this we recommend that acetaminophen use be reviewed for safety in children.