In a three-pronged study, UK investigators tested the hypothesis that polycystic ovary syndrome (PCOS) is linked with autism because both conditions are associated with elevated prenatal testosterone levels. Their findings, which may help inform new interventions for PCOS and autism, were published in Traditional Psychiatry.
The researchers obtained anonymized electronic medical records from the UK-based primary care Clinical Practice Research Datalink (CPRD) database. The population was restricted to females aged 21 years or older at the end of the study period who were registered in the CPRD between January 1, 1990 and December 31, 2014 with at least 3 months of recorded medical history prior to autism diagnosis.
Three matched case-control studies were conducted to test various aspects of the hypothesis. Study 1 (n=971, controls=4,855) examined risk of PCOS in women with autism compared to those without autism. Study 2 (n=26,263, controls=130,717) examined risk of autism in women with PCOS compared to those without PCOS. Study 3 (n=8,588, controls=41,127) examined risk of autism in first-born children of mothers with PCOS compared to first-born children of mothers without PCOS.
In Study 1, the authors found that a significantly higher percentage of women with autism were diagnosed with PCOS than the controls (2.3% vs 1.1%; unadjusted OR: 2.01, 95% CI 1.22-3.30). In Study 2, autism was almost two times more prevalent in PCOS cases than in controls (0.10% vs 0.05%; unadjusted OR: 2.01, 95% CI 1.26-3.20). In Study 3, mothers with PCOS had higher odds of having a child with autism than the controls (unadjusted OR: 1.60, 95% CI 1.28-2.00).
The authors acknowledge a few limitations to their study. Only first-born children of women with PCOS were included. Previous studies have shown a decreased prevalence of autism in first-born children which may have led to underestimation of rates of autism in the general public. The researchers also did not control for marital status, alcohol use, specific hormone or infertility treatments, and socioeconomic background, since these data were not recorded in CPRD. The data source also requires continuous registration with GPs, which may have limited the availability of children for follow-up autism diagnosis.
The authors believe that while their findings illustrate an association between PCOS and autism, the chance of having a child with autism is still very rare and should not be overstated.