A new study from researchers in Taiwan suggest that the month in which a child is born, and consequently the age at which the child starts school, can lead to a diagnosis of attention deficit hyperactivity disorder (ADHD) and being prescribed medication to treat the condition.

According to the Huffington Post, the research team’s findings show the children born in August, which would make them the youngest members of all their classmates in the same grade, were more likely to diagnosed than those born in September, the oldest members of the grade.

The data was analyzed from 380,000 schoolchildren in Taiwan, aged four to seventeen, and looked at a period of 14 school years.  The cutoff date for a child entering school in Taiwan is August 31, and as in other school systems, some of the children, born in September, are a few days shy of being a year older that those that failed to make the cutoff, born in late August.

Dr. Mu-Hong Chen, the study’s lead author and a child and adolescent psychiatrist at Taipei Veterans General Hospital in Taiwan said the research shows a child’s age relative to the age of their classmates may have an impact on the diagnosis of ADHD and the subsequent application of medication.

The study found August-born children were 1.65 times more likely to be diagnosed with the disorder, and 1.73 times more likely to receive medication to treat the symptoms.  Earlier research in the US and Canada has suggested the difference in ages of children within the same grade could lead to the child’s risk of being diagnosed as well.

However, the new study did not find the same to be true among teenage level adolescents, and Dr. Chen, saying he was not surprised at that finding, feels the maturity levels increase during the teen years, and the difference in the development levels in that age children may also decrease.

Dr. Chen added doctors need to consider a child’s age along with their grade level when diagnosing ADHD, and failure to recognize there could be maturity factors involved could lead to a misdiagnosis and unnecessary medications.

The findings from the research were published in The Journal of Pediatrics.