ADHD prevalence estimates across three decades: an updated systematic review and meta-regression analysis.
BACKGROUND
Previous studies have identified significant variability in attention-deficit / hyperactivity disorder (ADHD) prevalence estimates worldwide, largely explained by methodological procedures. However, increasing rates of ADHD diagnosis and treatment throughout the past few decades have fuelled concerns about whether the true prevalence of the disorder has increased over time.


METHODS
We updated the two most comprehensive systematic reviews on ADHD prevalence available in the literature. Meta-regression analyses were conducted to test the effect of year of study in the context of both methodological variables that determined variability in ADHD prevalence (diagnostic criteria, impairment criterion and source of information), and the geographical location of studies.


RESULTS
We identified 154 original studies and included 135 in the multivariate analysis. Methodological procedures investigated were significantly associated with heterogeneity of studies. Geographical location and year of study were not associated with variability in ADHD prevalence estimates.


CONCLUSIONS
Confirming previous findings, variability in ADHD prevalence estimates is mostly explained by methodological characteristics of the studies. In the past three decades, there has been no evidence to suggest an increase in the number of children in the community who meet criteria for ADHD when standardized diagnostic procedures are followed.
Department of Psychiatry, University of São Paulo Medical School, São Paulo, Brazil, Research Support Center on Neurodevelopment and Mental Health, University of São Paulo, São Paulo, Brazil, National Institute of Developmental Psychiatry for Children and Adolescents (INCT-CNPq), São Paulo, Brazil, Department of Psychology and Neuroscience, University of Colorado at Boulder, Boulder, CO, USA and ADHD Outpatient Program at the Child and Adolescent Psychiatric Division, Hospital de Clínicas de Porto Alegre, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
Guilherme V
GV
Polanczyk
Erik G
EG
Willcutt
Giovanni A
GA
Salum
Christian
C
Kieling
Luis A
LA
Rohde
D001289:Attention Deficit Disorder with Hyperactivity / Q000453:epidemiology*; D004812:Epidemiologic Methods; D014943:Global Health / Q000706:statistics & numerical data; D006801:Humans; D013997:Time Factors
ADHD; cross-cultural; epidemiology; methodology; prevalence; time