Boys face greater risk of autism if on a screen by aged one

Screen time at age one increases the risk of autism, but only for boys, a landmark new study from Japan finds.

Based on responses from Japanese mothers, the study found fewer than 10 per cent of one-year-olds had no daily screen time.

Boys who spent more time watching screens at age one were more likely to be on the autism spectrum at age three, a new study finds.

But for girls there was no ­association between autism spectrum disorder and screen time, the Japanese study of more than 80,000 toddlers concludes.

The paper, published in the American Medical Association’s journal JAMA Pediatrics, finds a “significant association” between screen time at age one for boys and ASD at age three. Each extra hour of screen time on television, computers or devices for boys at this age further increases their risk, it concludes.

Japanese academics from the Centre for Birth Cohort Studies at the University of Yamanashi said the study had factored in the likelihood of pre-existing ASD, leaving screen time as a stand-alone risk factor beyond genetics.

“Among boys, irrespective of their predisposition to ASD at one year of age, longer screen time at (that) age was associated with ASD at three years of age,” the study concludes.

“Among girls, however, there was no association between ­autism spectrum disorder and screen time,” it found.

Among the 84,000 Japanese children involved in the study, the prevalence of those with autism was about 0.4 per cent, or 392 per 100,000. Boys were three times more likely to have been diagnosed with ASD than girls.

Based on responses from Japanese mothers, the study found fewer than 10 per cent of one-year-olds had no daily screen time. Around half those surveyed said their one-year-old was on a screen between one and four hours a day.

By the time they had reached the age of three more than two-thirds said their child spent ­between one and four hours on a screen each day. “With the rapid increase in ­device usage, it is necessary to ­review the health ­effects of screen time on infants and to control ­excessive screen time,” the paper says.

The study confirms previous research concluding that autism spectrum disorder is not limited to those with a congenital condition, and can be due to environmental factors.

“Screen time during infancy, a period of rapid development, may be one of the acquired factors that may be associated with ASD, it says.

In 2019, the World Health ­Organisation published guidelines that recommended children not be exposed to screens at one year or younger. The American Academy of Pediatrics has also recommended that children not be exposed to screens until they are 18 months old.

But 90 per cent of children captured in the Japanese survey had been exposed to screens by age one, the report says, and a separate 2021 study by the Cabinet Office in Japan found 86 per cent of children younger than one were using mobile phones in some way.

“Screen time among children has increased worldwide. Amid this social climate, examining the associations of screen exposure with a child’s health is an important public health issue.”

The study notes that previous studies on the genetic factors contributing to the development of ASD had not been able to ­explain the male predominance, so genetic differences may be ­involved in the difference ­between boys and girls in terms of the association between autism and screen time.

The most recent Australian Bureau of Statistics data, published in 2018, finds about 95,800 Australian children have been diagnosed with autism and related disorders. About one-third of the 500,000 child and adult Australians in the National Disability Insurance Scheme have an ­autism diagnosis.