Référence bibliographique 
Spencer, Nicholas James, Ludvigsson, Johnny, Bai, Guannan, Gauvin, Lise, Clifford, Susan A., Awad, Yara Abu, Goldhaber-Fiebert, Jeremy D., Markham, Wolfgang, Faresjö, Ashild, Andersson White, Pär, Raat, Hein, Jansen, Pauline, Nikiema, Béatrice, Mensah, Fiona K. et McGrath, Jennifer J. 2022. «Social Gradients in ADHD by Household Income and Maternal Education Exposure During Early Childhood: Findings From Birth Cohort Studies Across Six Countries ». PLoS ONE, vol. 17, no 3, p. 1-13.
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«The paper aims to examine the relationship of household income and maternal education as separate measures of SES [socioeconomic status] exposure during early childhood to ADHD [Attention Deficit Hyperactivity Disorder] during late childhood in the different country settings represented by the participating cohorts.» (p. 3)
«Data were extracted from seven birth cohorts participating in the EPOCH [Elucidating Pathways Of Child Health inequalities] study: UK Millennium Cohort Study (MCS); Alla Barn i Sydöstra Sverige (All Babies in Southeast Sweden, ABIS); Quebec Longitudinal Study of Child Development (QLSCD); Longitudinal Study of Australian Children B cohort (LSAC B); Generation R, Rotterdam, The Netherlands (GenR); National Longitudinal Study of Children and Youth, Canada (NLSCY); and National Longitudinal Study of Youth, USA (US NLSY).» (p. 3) The sample consisted of 44,925 children aged between 9 and 11 years old.
Type de traitement des données :
According to the results, «[p]evalence of ADHD ranged from 1.3% in the UK to 7.6% in Quebec. Levels of maternal education at baseline varied widely by cohort: Quebec and UK cohorts have the largest proportion of mothers with low education (28.6% & 20.8%, respectively) and Sweden and Australia, the smallest (8.4% & 9.0% respectively); the proportion of mothers with high education was larger in Australia (47.8%) and Canada (all provinces, 42%), than in the remaining cohorts. […] For maternal education categories, social gradients were present in all cohorts, except Quebec. […] For household income tertiles, adjusted RRs for ADHD by household income tertiles showed a tendency towards social gradients in all cohorts, except for the Quebec cohort, where the risk was higher for middle than low income; confidence intervals for both estimates crossed unity in the Australian, US, and Canada (all provinces) cohorts.» (p. 5-6) «The absence of a gradient in maternal education in the Quebec cohort combined with the higher likelihood in the middle income group may be partly explained by long delays in the public system to access appropriate psychometric ADHD evaluation such that parents of more favorable socioeconomic status (i.e., more educated, higher income) can opt to pay for private services for testing rendering their children more likely to have an ADHD diagnosis […].» (p. 8)