Attention-deficit/hyperactivity disorder and the dopaminergic hypotheses

Abstract

Attention-deficit/hyperactivity disorder (ADHD) is a common psychiatric condition that affects approximately 5.3% of children worldwide. This disorder is defined by a combination of symptoms of inattention and hyperactivity/impulsivity. Diagnosis is based on impairment in these two domains determining several problems in personal and academic life. Although it is known that genetic and environmental factors are important in ADHD etiology, how these factors influence the brain and consequently behavior is still under debate. There seems to be a consensus in the literature that a fronto-subcortical dysfunction is responsible, at least in part, for the ADHD spectrum. Considering that these brain regions are rich in dopamine (DA), the DA hypothesis has an important role to understand ADHD pathophysiology. The main goal of the present review is to show evidence from different areas that support the idea that dysregulation in the DA system underlies ADHD. We discuss here evidences from animal models, pharmacology, brain imaging and genetics studies.

Keywords::

• ADHD
• brain imaging
• DAT1
• dopamine
• dopaminergic transmission
• DRD4
• genetics
• methylphenidate

Financial & competing interests disclosure

Luis A Rohde was on the speakers’ bureau and/or acted as a consultant for Eli-Lilly, Janssen-Cilag and Novartis in the last 3 years. Currently, his only industry-related activity is taking part in the advisory board/speakers’ bureau for Eli Lilly, Novartis and Shire (less than US$10,000 per year and reflecting less than 5% of his gross income per year). The ADHD and Juvenile Bipolar Disorder Outpatient Programs chaired by him received unrestricted educational and research support from the following pharmaceutical companies in the last 3 years: Abbott, Bristol-Myers Squibb, Eli-Lilly, Janssen-Cilag and Novartis. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.