A new study marks a step forward in figuring out the causes of autism spectrum disorder (ASD). ASD refer to a range of neurodevelopmental disorders characterized by language impairments, social disconnection, and repetitive behaviors. The term “spectrum” refers to the wide range of symptoms and severity levels. The underlying causes of ASD remain unclear. However, there has been evidence linking the development of ASD to exposure to certain sex hormones early in life. The sex hormones linked to ASD, called androgens, are responsible for the development of male-typical characteristics. The most well-known androgen is testosterone.
While all women produce androgens, women with polycystic ovary syndrome (PCOS) overproduce them, even during pregnancy. PCOS is one of the most common endocrine disorders. The abnormally high levels of androgen cause problems such as excessive hair growth, ovulation issues, and weight gain. The syndrome also causes many small cysts to grow on the ovaries. PCOS affects 5 to 15 percent of women of child-bearing age.
Swedish researchers, led by psychiatrist Kyriaki Kosidou, hypothesized children born to mothers with PCOS had an increased risk of developing ASD. They thought the sex hormones might influence the child’s developing nervous system and brain.
They drew data from national Swedish registers that collected health and sociodemographic data on the entire Swedish population. The study pool consisted of all the 4 to 17-year old children born in Sweden from 1984 to 2011. They identified approximately 24,000 ASD cases and compared them to 200,000 controls.
The data showed that children born to women with PCOS are 59 percent more likely to have an autism spectrum disorder than children born to a mother without the syndrome. "The risk was further increased among mothers with both PCOS and obesity, a condition common to PCOS that is related to [even] more severely increased androgens,” said Kosidou.
Among women with PCOS, 1.3 percent were underweight, 41.3 percent were of normal weight, 31.7 percent were overweight, and 25.7 percent were obese. In comparison, among women without PCOS, 3.8 percent were underweight, 67.7 percent were normal weight, 20.9 percent were overweight, and 7.6 percent were obese.
Autism spectrum disorders are five times more common in boys than in girls. Yet, children born to mothers with PCOS had the same risk of developing ASD regardless of gender.
"It is too early to make specific recommendations to clinicians in terms of care for pregnant women with PCOS," said senior investigator Renee Gardner. The study still needs to be replicated and further studies need to be done to explore the mechanisms behind how PCOS affects the development of ASD.
“While we did observe an increased risk for ASD, it was a modest increase for a relatively rare disorder. Chances are that children born to a mother with PCOS will not develop autism," Kosidou told
the Huffington Post.
The study was publicly published on December 8, 2015, in the journal Molecular Psychiatry
via Molecular Psychiatry, Karolinska Institutet press release
via Science Daily
, Huffington Post