Previous Exposure to Anesthesia and Autism Spectrum Disorder (ASD): A Puerto Rican Population-Based Sibling Cohort Study.

Background: Autism Spectrum Disorder (ASD) is characterized by impaired social interaction and communication, and by restricted and repetitive behavior, that begins usually before a child is three years old.(1) Researchers have shown that prevalence rates in the U.S. may be as high as 1 in 68.(52) A number of studies have examined the effects of early exposure to anesthesia on brain development and subsequent impairment in neurocognitive function; yet, little is known about the possible effects of anesthetic agents on social-behavioral functioning. The association between exposure to anesthesia either in uterus, during the first years of life, or later and development of Autistic Spectrum Disorder (ASD) or its severity was determined in a retrospective population based cohort study.

Objectives: Identify if children who had previous exposure to anesthesia either in uterus, first years of life during their developing brain years, or later, are at risk of developing ASD and its severe form of the disease.

Methods: Data was obtained from structured interviews administered to a sample of 515 parents/guardians distributed in two groups: ASD = 262 children diagnosed with this condition and Non-ASD: 253 children (siblings of ASD group) without diagnosis (95% confidence interval) that freely decided to participate and agreed to a consent form. Variables studied include: demographics, diagnosis and severity of ASD, exposure to anesthesia, method of childbirth, and age of exposure Children less than 2 years of age were considered into have developing brain period. Data was analyzed using Chi-square or Fisher exact test.

Results: In contrast to non-ASD group, most of the children within ASD group were male, 76% (p=0.0001). With regards to methods of childbirth, 64% of the ASD population were vaginal delivery (VD; Non-anesthesia exposure group) and 36% cesarean delivery (CD) compared to non-autistic population with 71% VD and 29% CD, which demonstrates no statistical difference between both groups (p=0.1113). Out of the 36% of ASD population that underwent CD, 7% were performed using general anesthesia and 93% regional anesthesia, while the 29% of the CD of non-ASD, 5% were performed using general anesthesia and 95% regional anesthesia. This reveals no statistical significance (p=0.7569) with the development of ASD and the type of anesthesia used when comparing ASD with non-ASD patients. In view of severity of autism, in VD, 56% of ASD population had mild form of the disorder, 34% moderate, and 10% severe; while CD had a 54% mild form of the disorder, 33% moderate, and 13% severe. This shows no statistical association (p=0.8069) when comparing exposure to anesthesia in uterus to subsequent severe form of ASD. Of the 262 ASD patients, 99 had exposure to anesthetics before their diagnosis, while in Non-ASD population, 110 had exposure to anesthesia, demonstrating no statistically significant association between both groups (p=0.2091). Out of 99 ASD patients exposed to anesthesia prior to their diagnosis, 72 were exposed before age 2. When compared to the 110 Non-ASD patients exposed to anesthesia, 86 had exposure during this developing brain period, which indicates no statistically significant association (p=0.4207). In addition, most of the ASD children exposed to anesthesia during developing brain were diagnosed with mild degree of the disorder when compared to ASD children without any previous exposure to anesthesia (p=0.9700) during the same period. When the exposure occurred after age 2, ASD children developed mild form of the disorder as compared with ASD children without any previous exposure to anesthesia (p=0.1699) in that period.

Conclusions: Children under early exposure to anesthesia in uterus, first 2 years of life, or later are not more likely to develop neither ASD nor severe form of the disorder.