A study carried out by the University of Turku has suggested that younger children in each age cohort are more likely to be diagnosed with a learning disorder, and that children born in December are almost twice as likely to be diagnosed with a learning disorder than those born in January.
The research initially included nearly 400,000 children born in Finland from 1996 to 2002, excluding twins. The follow-up focused on over 3,000 (or 0.8 percent of the original sample) children that were diagnosed with a specific learning disorder, such as with reading, writing and maths.
"From a clinical point of view, the mounting evidence of relative age effects on psychiatric, cognitive, and other health‐related adversities indicates that children's relative age is an important factor to consider in paediatric care," the report's authors wrote in the conclusion.
"From an educational perspective, increased flexibility in the time when less mature children start school might be justified, but further research on the topic is warranted."
In previous studies, children born later in the year, and therefore younger than their classroom peers, have been found to be at increased risk of psychiatric disorders, low academic achievement, and being bullied.
However, there have been no previous studies of the association between clinically diagnosed specific learning disorders and relative age.
Over- and under-diagnoses
The study compared children with both a learning disability diagnosis and ADHD separately from children with learning disabilities but without ADHD, as ADHD was found not to affect the association between month of birth and the likelihood of a learning disability diagnosis.
The data also found that children born later in the year were more regularly sent to be tested for possible learning disabilities, which the authors suggested may mean that older children within a classroom may not be getting the diagnosis they need.
"It appears that relatively younger children are more likely to be referred to specialist care," PhD student and medical doctor Bianca Arrhenius said in a statement.
The university's press release added that the relative age of children — meaning the age of the child in relation to the age of other children within the same grade or classroom — should be taken into account when assessing the child's learning ability.
"There is a risk of both over- and under-diagnosis here, meaning that the youngest in the class are diagnosed in proportion so much more, that the elders in the class may even be deprived of the diagnosis and rehabilitation they need. A more systematic screening for learning disabilities could be one approach that would smooth out the effect of relative age on referrals for specialist care," Arrhenius said.
The University of Turku's study, entitled 'Relative age and specific learning disorder diagnoses: A Finnish population‐based cohort study' was published in the JCPP Advances academic journal.