ReviewSex differences in Attention Deficit Hyperactivity Disorder: Candidate genetic and endocrine mechanisms

- ADHD is a common developmental disorder linked to long-term adverse consequences.
- ADHD prevalence and presentation are affected by sex.
- Sex-linked genetic mechanisms fundamentally contribute to establishing these biases.
- Such mechanisms act directly on the brain or via intermediaries e.g. androgen levels.
- Understanding sex effects in ADHD will improve diagnosis, prognosis and treatment.

Attention Deficit Hyperactivity Disorder (ADHD) is a developmental condition characterised by severe inattention, pathological impulsivity and hyperactivity; it is relatively common affecting up to 6% of children, and is associated with a risk of long-term adverse educational and social consequences. Males are considerably more likely to be diagnosed with ADHD than females; the course of the disorder and its associated co-morbidities also appear to be sensitive to sex. Here, I discuss fundamental biological (genetic and endocrine) mechanisms that have been shown to, or could theoretically, contribute towards these sexually dimorphic phenomena. Greater understanding of how and why the sexes differ with respect to ADHD vulnerability should allow us to identify and characterise novel protective and risk factors for the disorder, and should ultimately facilitate improved diagnosis, prognosis and treatment.