http://www.digitaljournal.com/life/health/does-the-month-of-birth-affect-adhd-likelihood/article/463378

Does the month of birth affect ADHD likelihood?

Posted Apr 20, 2016 by Tim Sandle
New research suggests a seasonal pattern to ADHD. The youngest children in a school grade are more likely to be diagnosed with attention-defici t/hyperactivity disorder compared with the oldest children.
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China has a national school system for training professional chefs and other professions. Beijing's School of Culinary Arts is part of the Jinsong Vocational School that graduates 1,500 students every year in 11 different occupations. School visitors have a chance to sample the latest, and best, in cuisine de Chine.
Attention deficit hyperactivity disorder (ADHD) is a psychiatric disorder, characterized by problems paying attention, excessive activity, or difficulty controlling behaviour. The condition is more common in children. The causes are uncertain and may vary according to individuals. In all probability, there is a mix of genetic and environmental factors at play. ADHD affects around 7 percent of children worldwide. However, in some regions the rates are considerably higher. According to the U.S. Centers for Disease Control and Prevention, the rate in the U.S. is closer to 15 percent.
In the new study, psychologists examined 378,881 children aged between four and 17 years old. The children were all based in Taiwan. ADHD rates were examined against school enrollment dates. Here the cut-off date was August 31, which meant that students born in August were the youngest in their class, whereas children born in September were oldest.
The review discovered that 1.8 percent of the students born in September were diagnosed with ADHD compared to 3 percent of those born in August. With the pattern, no gender difference was apparent (which contradicts other studies.)
While the findings are consistent with studies in the U.S. showing that “relative age, as an indicator of neurocognitive maturity, may play a crucial role in the risk of being diagnosed with ADHD and receiving ADHD medication,” the reasons for this remain unknown.
The research is published in the Journal of Pediatrics. The study is titled “Influence of Relative Age on Diagnosis and Treatment of Attention-Deficit Hyperactivity Disorder in Taiwanese Children.”
As well as seasonality, and despite differences from the Tiawanese study, a further factor appears to be gender. Further studies indicate males are almost three times more likely to develop the condition compared with females. Here, almost 13 percent of men will be diagnosed with ADHD at some point, compared to around 5 percent of women. According to Laboratory Roots, exploring this difference is part of a research project being run from Yale University in New Haven Connecticut. A researcher called Dr. Bruce Wexler thinks that ADHD is caused by the neurons in the brain becoming ‘mis-wired’ and that it could be possible, through exercises designed to stimulate the brain, to ‘re-wire’ these neurons and alleviate the effects of the condition.