Children’s Relative Age and ADHD Medication Use: A Finnish Population-Based Study

Abstract

OBJECTIVES: The youngest children in a classroom are at increased risk of being medicated for attention-deficit/hyperactivity disorder (ADHD). We examined the association between children's birth month and ADHD medication rates in Finland. METHODS: Using a population-based study, we analyzed ADHD medication use among children born in 2005 to 2007. Cases (n = 7054) were identified from the first purchase of medication for ADHD. Cox proportional hazard models and hazard ratios (HRs) were examined by birth month and sex. Finnish children start first grade in the year of their seventh birthday. The cutoff date is December 31. RESULTS: Risk of ADHD medication use increased throughout the year by birth month (ie, January through April to May through August to September through December). Among boys born in September to December, the association remained stable across cohorts (HR: 1.3; 95% confidence interval [CI]: 1.1-1.5). Among girls born in September to December, the HR in the 2005 cohort was 1.4 (95% CI: 1.1-1.8), whereas in the 2007 cohort it was 1.7 (95% CI: 1.3-2.2). In a restricted follow-up, which ended at the end of the year of the children's eighth birthday, the HRs for boys and girls born in September to December 2007 were 1.5 (95% CI: 1.3-1.7) and 2.0 (95% CI: 1.5-2.8), respectively. CONCLUSIONS: Relative immaturity increases the likelihood of ADHD medication use in Finland. The association was more pronounced during the first school years. Increased awareness of this association is needed among clinicians and teachers. WHAT'S KNOWN IN THIS SUBJECT: The relative age effect (RAE) in attention-deficit/hyperactivity disorder (ADHD) indicates that ADHD medication use is more common in the relatively youngest children within a school grade. Within-country sex differences in ADHD medication use vary and are among the largest in Finland. WHAT THIS STUDY ADDS: This population-based study reveals that the RAE in ADHD medication use among children was more pronounced during the first school years (ages 6-8). The RAE in ADHD medication was stable among boys across 3 cohorts but increasing among girls.

Age at school entry and reported symptoms of attention-deficit/hyperactivity in first graders: results of the prospective cohort study ikidS

“…Our results tentatively suggest a gender-specific ASE effect, which is in line with other studies also showing a more pronounced relative age effect in girls compared to boys [ 36 , 37 , 39 ], although in these studies—as in ours—the proportion of actual or suspected cases of ADHD was higher among boys than among girls. On the basis of both the oversupply and the stress-related hypothesis, we would have expected the ASE effect to be stronger in boys because of the greater immaturity of boys compared to girls [ 15 ].…”

Relative Age and Psychotropic Drug Use in Preterm and Term-Born Children and Young Adults

“…Earlier literature supports the same tendency, without taking gestation into account, finding that children born late in the academic year are more often diagnosed with, and more often prescribed medication for, ADHD. [12][13][14][15]24 Earlier research on term born individuals suggests that relatively younger age is also related to other adverse mental health effects. 25 A recent study including ten million people found that low relative age was associated with diagnoses of anxiety, depressive disorders, ADHD, and with prescription of ADHD medication and antidepressants.…”

“…Such influences on children of their chronological age relative to their classmates' age is often referred to as "relative age effect". Studies show that younger age in a school class increases the risk of being diagnosed with ADHD and prescribed psychostimulant medication [12][13][14][15][16][17] , and that this effect is most pronounced in girls 13 . Relative age effects may be understood as a consequence of organization of the educational system, school entry and class environments, supported by research from e.g.…”

Impact of transcranial alternating current stimulation on working memory and selective attention in athletes with attention deficit hyperactivity disorder: randomized controlled trial

“…Studies highlight the comorbidity of specific complications such as limited effects, disquietude, headache, palpitations, and so on, with therapeutic methods [11]. On the other hand, regarding the importance of selective attention on the cognitive performance of ADHD children, especially hyperactive athlete children, new treatment methods are required to help better manage these children [12,13]; Thus, considering the difficulties caused by ADHD, including attention deficiency, the researchers have suggested using new treatment options and tools, such as transcranial alternating current stimulation (tACS) to cure cognitive and behavioral problems caused by ADHD [14][15][16][17].…”