Being born in December does not mean you are more likely to develop a attention deficit hyperactivity disorder (ADHD). However, it can increase the probability of receiving this diagnosis during childhood when the youngest children in a class are compared with peers who may be almost a year ahead of them.
The psychologist Rafa Guerrero has focused on this phenomenon by remembering that children born in December have a 39% more likely to be diagnosed with ADHD than those born in January. The explanation is not that the month of birth causes the disorder, but rather in the difference in maturity that may exist between students in the same grade.
In the same class, children born at the beginning of January may coincide with others born at the end of December. The difference between the two can be close to 11 monthsan especially relevant period during the first years of life, when physical, emotional and cognitive development advances rapidly.
Up to 11 months difference within the same class
The call relative age helps understand why the month of birth can influence the way a child’s behavior is interpreted. Two students can be of the same school age and yet be at different stages of maturation.
This gap can be noticed in aspects such as ability to remain seated, maintain attention, control impulses, or complete tasks. A child born in December may display behaviors that are normal for his or her chronological age, but that appear more immature when compared to a peer born almost a year earlier.
Guerrero sums up the problem in that direct comparison. Asking exactly the same thing to two children with several months of difference in development can lead to interpreting as a possible disorder behaviors that may also be related to their own maturity.
ADHD is not diagnosed with a single test
Another point highlighted by the psychologist is that the diagnosis of ADHD does not depend on an isolated test. There is no single test, analysis or neuroimaging that can confirm by itself that a child has this disorder.
The assessment is made from the symptoms, their intensity, the frequency with which they appear and the impact they have in different contexts. Therefore, the age of the minor and his or her level of development are especially important when interpreting certain behaviors.
Confusing immaturity with symptoms compatible with ADHD can increase the risk of overdiagnosis among the youngest students in a class. Precisely for this reason, specialists insist on observing whether difficulties appear persistently and in different environments, such as school and home.
Study followed nearly a million children
The difference pointed out by Guerrero is supported by research carried out in British Columbia which followed almost a million school-age children for nearly 11 years.
The results showed that the youngest students in each grade received ADHD-related diagnoses and treatments more frequently than those who were born at the beginning of the year.
The data also showed differences between boys and girls. Among those born in December, an increase in diagnoses was observed compared to those born in January, although the figures varied according to sex. The pattern pointed, in any case, in the same direction, with greater frequency among those who occupied the youngest part of the grade.
What families and teachers can do
Taking into account the month of birth does not mean discarding possible difficulties nor delay an evaluation when there are clear signs. The key is to avoid making comparison with more mature peers the only criterion for interpreting behavior.
Families can observe how the child acts outside of school and check if the difficulties are also repeated at home or in other situations. If the attention, impulsivity, or behavioral problems appear persistently in different areas, it is appropriate to resort to a professional assessment.
In the classroom, teachers can keep in mind the relative age when assessing performance, attention span, or impulse control. Adjusting certain expectations to the student’s actual age can help differentiate between a maturity gap and a difficulty that needs specific attention.
Being born in December does not cause ADHD
The figure of 39% does not mean that children born in December have more ADHD because they were born in that month. What it reflects is a greater chance of receiving the diagnosis when comparing the youngest students with the oldest students in the same class.
The CADAH Foundation It also states that the risk of diagnosis increases among those born in the last months of the year and progressively decreases as the relative age within the group increases. One possible explanation is that normal developmental differences may be interpreted as symptoms or that younger children are more likely to be referred for evaluation.
For this reason, the month of birth can be a relevant piece of information within a broader evaluation, but never an explanation on its own. The difference between January and December can be equivalent to almost a year of development, and during childhood that margin can be enough for two children in the same class to show very different levels of maturity.