The Importance of Relative Standards in ADHD Diagnoses: Evidence Based on Exact Birth Dates

Economics Department, Michigan State University, East Lansing, MI 48824-1038, USA.
Journal of Health Economics (Impact Factor: 2.58). 09/2010; 29(5):641-56. DOI: 10.1016/j.jhealeco.2010.06.003
Source: PubMed


This paper presents evidence that diagnoses of attention-deficit/hyperactivity disorder (ADHD) are driven largely by subjective comparisons across children in the same grade in school. Roughly 8.4 percent of children born in the month prior to their state's cutoff date for kindergarten eligibility - who typically become the youngest and most developmentally immature children within a grade - are diagnosed with ADHD, compared to 5.1 percent of children born in the month immediately afterward. A child's birth date relative to the eligibility cutoff also strongly influences teachers' assessments of whether the child exhibits ADHD symptoms but is only weakly associated with similarly measured parental assessments, suggesting that many diagnoses may be driven by teachers' perceptions of poor behavior among the youngest children in a classroom. These perceptions have long-lasting consequences: the youngest children in fifth and eighth grades are nearly twice as likely as their older classmates to regularly use stimulants prescribed to treat ADHD.

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    • "Indeed, two recent studies showed that the youngest children in a given grade were much more likely to be diagnosed with attentiondeficit/hyperactivity disorder (ADHD) than their older classmates (Elder, 2010; Evans, Morrill, & Parente, 2010). Teachers' perceptions of student behavior were a driving force behind these increased diagnoses, and Elder (2010) proposed that teachers may be comparing younger children with their more mature classmates when reporting ADHD symptoms. Similarly, younger children tend to receive more referrals for special education and mental health services than their older classmates, despite few differences in objective measures of children's skills (Gledhill, Ford, & Goodman , 2002; Wallingford & Prout, 2000). "
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    ABSTRACT: Preschool teachers have important impacts on children's academic outcomes, and teachers' misperceptions of children's academic skills could have negative consequences, particularly for low-income preschoolers. This study utilized data gathered from 123 preschool teachers and their 760 preschoolers from 70 low-income, racially diverse centers. Hierarchical linear modeling was utilized to account for the nested data structure. Even after controlling for children's actual academic skill, older children, children with stronger social skills, and children with fewer inattentive symptoms were perceived to have stronger academic abilities. Contrary to hypotheses, preschoolers with more behavior problems were perceived by teachers to have significantly better pre-academic abilities than they actually had. Teachers' perceptions were not associated with child gender or child race/ethnicity. Although considerable variability was due to teacher-level characteristics, child characteristics explained 42% of the variability in teachers' perceptions about children's language and preliteracy ability and 41% of the variability in teachers' perceptions about math ability. Notably, these perceptions appear to have important impacts over time. Controlling for child baseline academic skill and child characteristics, teacher perceptions early in the preschool year were significantly associated with child academic outcomes during the spring both for language and preliteracy and for math. Study implications with regard to the achievement gap are discussed.
    No preview · Article · Aug 2015 · Journal of Educational Psychology
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    • "Recent studies suggest that a within-grade relative maturity disadvantage in childhood could have long-lasting negative effects on personal achievements and health outcomes (Bedard & Dhuey, 2006; Goodman, Gledhill, & Ford, 2003; Helsen, Van Winckel, & Williams, 2005). Studies from North America and Iceland also showed that the youngest children in the grade are more likely to be diagnosed and treated for ADHD (Elder, 2010; Evans, Morrill, & Parente, 2010; Morrow et al., 2012; Zo€ ega, Valdimarsd ottir, & Hern andez-D ıaz, 2012). The prevalence of use of medication for ADHD in children ranged from 3.7% to 6.3% in these studies, and the relative difference of use between the youngest and the oldest groups in the class ranged from approximately 50% (Canada, Iceland ) to 100% (United States). "
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    ABSTRACT: Background Previous studies from North America and Iceland have shown that the youngest children within a grade are up to twice as likely to be diagnosed and treated for attention-deficit/hyperactivity disorder (ADHD) compared with their older classmates. We aimed to investigate whether younger age in class is associated with an increased probability of being prescribed medication for ADHD among school-aged children in Denmark.Methods We followed all Danish children between 2000 and 2012 from 1st through 6th grade (7–12 years). Among children who started school on their age-assigned grade level, we estimated the prevalence proportion ratio (PPR) of receiving ADHD medication between the youngest children in class (born in October–December) and the oldest in class (born in January–March), specified by grade level, calendar year and gender. As a sensitivity analysis, we added children not on their age-assigned grade level to the main calculations.ResultsWe identified 932,032 eligible children for the main analysis, of whom 17.3% were among the youngest and 26.5% among the oldest in class. In total, 1.2% eligible children filled at least one prescription for ADHD medication in 2000–2012. The average PPR over the study period was 1.08 (95% CI, 1.04–1.12) and remained stable across subgroups and sensitivity analyses. Overall, 40% of children born October–December had entered school a year after their age-assigned grade level.Conclusions Contrary to previous study results, we observed almost no relative age effect on medication use for ADHD among children in Denmark. We postulate that this may be due to the high proportion of relatively young children held back by 1 year in the Danish school system and/or a generally low prevalence of ADHD medication use in the country.
    Full-text · Article · May 2014 · Journal of Child Psychology and Psychiatry
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    • "However, although large cohorts were studied, the age distribution was limited and no information available on ADHD in adulthood (22,371 7-17 year-olds and 937,943 6–12 year-olds, respectively). The study by Elder (Elder, 2010) was a longitudinal, multisite Kindergarten cohort study from the United States (initially including 18,644 children) with follow-ups until eighth grade including symptom ratings from both parents and teachers. The only European study of ADHD and relative immaturity in the school setting so far, was a population-based cohort study including all 9–12 year old children on Iceland (n = 11,785; Zoega et al., 2012). "
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    ABSTRACT: Background We addressed if immaturity relative to peers reflected in birth month increases the likelihood of ADHD diagnosis and treatment.Methods We linked nationwide Patient and Prescribed Drug Registers and used prospective cohort and nested case–control designs to study 6–69 year-old individuals in Sweden from July 2005 to December 2009 (Cohort 1). Cohort 1 included 56,263 individuals diagnosed with ADHD or ever used prescribed ADHD-specific medication. Complementary population-representative cohorts provided DSM-IV ADHD symptom ratings; parent-reported for 10,760 9-year-old twins born 1995–2000 from the CATSS study (Cohort 2) and self-reported for 6,970 adult twins age 20–47 years born 1959–1970 from the STAGE study (Cohort 3). We calculated odds ratios (OR:s) for ADHD across age for individuals born in November/December compared to January/February (Cohort 1). ADHD symptoms in Cohorts 2 and 3 were studied as a function of calendar birth month.ResultsADHD diagnoses and medication treatment were both significantly more common in individuals born in November/December versus January/February; peaking at ages 6 (OR: 1.8; 95% CI: 1.5–2.2) and 7 years (OR: 1.6; 95% CI: 1.3–1.8) in the Patient and Prescribed Drug Registers, respectively. We found no corresponding differences in parent- or self-reported ADHD symptoms by calendar birth month.Conclusion Relative immaturity compared to class mates might contribute to ADHD diagnosis and pharmacotherapy despite absence of parallel findings in reported ADHD symptom loads by relative immaturity. Increased clinical awareness of this phenomenon may be warranted to decrease risk for imprecise diagnostics and treatment. We speculate that flexibility regarding age at school start according to individual maturity could reduce developmentally inappropriate demands on children and improve the precision of ADHD diagnostic practice and pharmacological treatment.
    Full-text · Article · Mar 2014 · Journal of Child Psychology and Psychiatry
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