Tokyo, Oct 26 : Children with a genetic predisposition to autism spectrum disorder (ASD) were more likely to use screens for longer periods, according to a study. While long periods of screen time in childhood have been suggested to be a cause of ASD/attention deficit hyperactivity disorder (ADHD), the results of this study suggest that some people may have a genetic disposition to use screens because of ASD. The findings, published in the journal Psychiatry Research, showed that children with a higher genetic susceptibility to ASD used devices with screens longer (3 hours a day or 4+ hours a day) from early childhood. They also found that kids with a high genetic risk of attention deficit hyperactivity disorder (ADHD) gradually increased their screen time as they grew older, even if their initial screen use time was short. 'Overall, those with a genetic risk of ASD were 1.5 times more likely to be in the group with about three hours of screen time per day, and 2.1 times more likely to be in the group with more than four hours of screen time,' said lead researcher Nagahide Takahashi of Nagoya University in Japan. 'Screen time may be an early sign of ASD, rather than a cause, as children with ASD are often more attracted to objects than people. Physicians should know that it is not fair to conclude that prolonged screen time is a risk factor for the development of ASD,' Takahashi said. Researchers examined 6.5 million polymorphisms -- referring to the presence of two or more variant forms of a specific DNA sequence that can occur among different individuals or populations -- in 437 children's DNA to determine genetic susceptibility to ASD and ADHD. Next, they calculated a genetic risk index that considers the number and size of the effects of changes in genes associated with ASD/ADHD. This is known as a "polygenic risk score'. The researchers then compared it with the amount of time spent using screens devices among a sample of children aged 18, 32, and 40 months. Takahashi also warned against overexposing children with ADHD to device screens. 'Our results suggest that children at risk of ADHD are at risk of having too much screen time, especially since gaming addiction is common. As screen time tends to be longer for children who are particularly susceptible to ADHD, parents and caregivers should be cautious about it and make a commitment before it becomes a problem,' he noted. These results may also help parents devise better child-rearing strategies. 'Parents of children with neurodevelopmental disorders may feel guilty or be criticised by others for allowing their children screen time,' Takahashi said. 'However, we would recommend offering help to caregivers including offering alternative behavioural management strategies.' /IANS