Maternal Sleep Apnea During Pregnancy May Heighten Autism Risk in Children

The children of women who experience sleep apnea during pregnancy may be at a heightened risk of developing autism, according to a new report.

The report is based on an animal model of gestational sleep apnea. It highlights the importance of identifying expectant mothers who may be experiencing sleep apnea. The study was published in the journal PLoS Biology.

Michael E. Cahill, Ph.D., an assistant professor at the University of Wisconsin, Madison, noted that there is a good deal of evidence that genetic factors and early life experiences play an important role in the pathogenesis of many psychiatric disorders. Bu, he and colleagues said, relatively little is known about which prenatal and perinatal experiences can affect risk.

In sleep apnea, patients experience frequent interruptions of breathing during sleep, leading to intermittent hypoxia. Cahill and his colleagues wondered whether hypoxia pregnant women might translate into psychiatric problems for their children later in life.

To find out, the investigators used an animal model in which pregnant rats were exposed to intermittent low oxygen levels while resting during the second half of their gestational period. During pregnancy, the mothers experienced hypoxia, though the offspring did not. This much was expected, the authors said.

However, once the offspring were born, investigators began to notice behavioral abnormalities, including altered distress vocalization patterns. In males, cognitive and social function appeared to be impaired. Experiments designed to assess memory and interest in social interaction also pointed to deficit among the offspring of the animals exposed to hypoxia.

Cahill’s research focus on denditric spines, the structures that connect brain cells to one another. When Cahill and colleagues looked closer, they found abnormalities in the density and morphology of dendritic spines.The males, in particular, having an elevated density of dendritic spines. The investigators attributed this to a lack of spine “pruning,” which they said is an important component of normal brain development.

They also found that the offspring had excessive activity in the mTOR signaling pathway, which is similarly found in humans with autism.

The findings suggest maternal sleep apnea could have significant implications for the risk of neuropsychiatric disorders in children.

“Unfortunately, routine screening for sleep apnea during pregnancy is not common,” Cahill told Managed Healthcare Executive.

One reason, he said, is that many women who develop sleep apnea during pregnancy do not have a prior history of sleep problems, and the sleep apnea itself can be transient. Therefore, screening for sleep apnea is not discussed. Another problem, he said, is that the questionnaires typically used to screen patients for sleep apnea can be unreliable.

“Proper determination of sleep apnea would at the very least require an at-home study involving the monitoring of blood oxygen saturation fluctuations during sleep,” he said.

However, he said the reality is most obstetricians do not consider sleep apnea, and so he suspects most women who develop transient sleep apnea are not aware of it and not treated for it.

The study raises the question of whether better screening and treatment of sleep apnea in pregnant women might reduce the risk of autism in their children. However, Cahill said this would be a difficult question to study in a clinical trial, since investigators would have an obligation to treat patients diagnosed with sleep apnea. Thus, it would not be feasible to have an untreated “control” group. He said future studies could perhaps compare groups based on compliance with sleep apnea therapy to see whether the children of treatment-compliant patients had lower rates of autism or similar disorders.

“That said, it is clear in the scientific literature that sleep apnea during pregnancy is associated with a variety of adverse risks to both the neonate and the mother,” he said, “and it seems logical to conclude that treating the sleep apnea would lessen these risks.”