In the 1990s, diagnoses of ADD (attention-deficit disorder) and then ADHD (attention-deficit hyperactivity disorder) boomed, aided by public school teachers who didn't want to deal with diverse personalities in the classrooms and sketchy therapists exploiting the worries of parents.

Obviously it is a real condition also, but like many mental health fads (people declared that everyone they didn't like had Asperger's Syndrome a decade ago, for example) a lack of clinical relevance means it gets used in many cases where it should not be. Now, some reports have indicated a prevalence of up to 15% - but just in Western countries, where more money than sense is in evidence.

What could also be influencing it? Immaturity. A paper upcoming in The Journal of Pediatrics found that a child's age at school entry impacted the diagnosis of ADHD. Dr. Mu-Hong Chen and colleagues from Taipei and Taoyuan, Taiwan, examined cohort data from 378,881 children ages 4-17 years from 1997 to 2011 and evaluated the prevalence of being given a diagnosis of ADHD and/or prescribed ADHD medication. Using the Taiwanese annual cut-off birth date of August 31 for school enrollment, the researchers compared the youngest children in a grade (those born in August) with the oldest (those born in September) and assessed whether age was associated with being diagnosed with ADHD and/or being medicated.

When looking at the database as a whole, children born in August were more likely to be diagnosed with ADHD and be given ADHD medication than those born in September. When broken down and analyzed according to age, only preschool or elementary school-aged children born in August had an increased risk of being diagnosed with ADHD and receiving ADHD medication. However, adolescents born in August did not have an increased risk of ADHD diagnosis. This may imply that increasing age and maturity lessens the impact of birth month on ADHD diagnoses.

Relative age - maturity - which may be a proxy of neurocognitive ability, may increase the likelihood of ADHD diagnosis and medication. Since medications for ADHD have dramatic side effects, they should not be prescribed casually.

According to Dr. Chen, "Our findings emphasize the importance of considering the age of a child within a grade when diagnosing ADHD and prescribing medication to treat ADHD."