Psychology, 2017, 8, 412-423 http://www.scirp.org/journal/psych ISSN Online: 2152-7199 ISSN Print: 2152-7180 DOI: 10.4236/psych.2017.83025 February 24, 2017 Characterization of Epidemiological ADHD Studies: A Systematic Review João Paulo dos Santos Nobre, Ana Flávia Lima Teles da Hora, Abraão Roberto Fonseca, Simone Souza da Costa Silva, Fernando Augusto Ramos Pontes Federal University of Pará, Belém, Brazil Abstract Attention Deficit Hyperactivity Disorder is a multidetermined phenomenon of high incidence affecting children, adolescents and adults worldwide, re- sulting in impairment in several areas of development such as social relation- ships, academic performance, professional and romantic relationships. The objective of this study was to review systematically the literature to verify the epidemiological picture of the disorder under three main aspects: 1) what is the ADHA definition; 2) what is the epidemiology of the disorder; and 3) what are the instruments used for diagnostic evaluation. The search was per- formed in the database Periódicos CAPES, PsicInfo, and MedLine using the keywords “Epidemiology and ADHD” and its correlation in English and Spanish. 331 articles, of which only 21 met the inclusion criteria, were re- trieved. The results suggest that there is a consensus on the ADHD definition; however epidemiological data ranged from 0.04% to 24.5%. The studies also varied as to the use of diagnostic instruments, being more used the DSM-IV criteria. Keywords ADHD, Epidemiology, Diagnosis, Prevalence, Diagnostic Instruments 1. Introduction Attention Deficit Hyperactivity Disorder (ADHD) is the most common neuro- development disorder in childhood and may persist during adolescence and adulthood. ADHD is characterized by three main symptoms: inattention, hyperactivity and impulsivity (Conners, 1999; Homer et al., 2000; Mercugliano, 1999). The disorder comprises impairments in behavioral inhibition, sustained attention, resistance to distraction, and in regulating the activity level of the person in specific situations, being frequently observed excessive and irrelevant How to cite this paper: Nobre, J. P. S., Hora, A. F. L. T., Fonseca, A. R., Silva, S. S. C., & Pontes, F. A. R. (2017). Characteriza- tion of Epidemiological ADHD Studies: A Systematic Review. Psychology, 8, 412-423. https://doi.org/10.4236/psych.2017.83025 Received: November 25, 2016 Accepted: February 21, 2017 Published: February 24, 2017 Copyright © 2017 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY 4.0). http://creativecommons.org/licenses/by/4.0/ Open Access