HARTFORD, APRIL 5 If Junior is hyper, could tons of tube time as a toddler be to blame? A study published on Monday suggests that television viewing by children at age one and at age three increases their risk of having an attention disorder by the time they are seven.

The study’s authors speculate that watching TV makes changes in the wiring of the developing brain, which is undergoing rapid growth in the first few years of life. Those changes may make children more susceptible to Attention Deficit/Hyperactivity Disorder, or ADHD. Child psychiatrists caution that the theory needs more research to be confirmed. ‘‘I wouldn’t change my behaviour based on this study,’’ said Dr. Robert Riccio, clinical psychologist at the child development centre at the Connecticut Children’s Medical Centre.

The study — published in Pediatrics, the journal of the American Academy of Pediatrics — looked at records of more than 2,500 children who have participated in a long-term children’s health study.

Researchers at the University of Washington found that 10 per cent of the children had attention disorders at age 7. The researchers then looked back at the children’s TV viewing habits and found that TV viewing increased the risk of having an attention problem by 9 per cent for every hour of TV watched a day.

The new study did not take into consideration the content of the TV shows viewed and relied upon reports of parents about their child’s viewing habits.

The findings strongly support recommendations by the Pediatrics Academy that children under age 2 not watch TV at all, said Frederick Zimmerman, assistant professor in the school of public health at the University of Washington.