METHODS: This is a narrative literature review. A bibliographic search was performed on PubMed and PsychNet databases and topic-related publications were included without date of publication or study design limits.
RESULTS: Siblings of patients with ADHD have a higher likelihood of having this disorder when compared to controls, with odds ratios (OR) ranging between 11.4 and 13.5. Among these siblings, ADHD prevalence ranges between 26 and 45.2%. Siblings with ADHD and those without ADHD have an increased risk of having other disorders, the most frequent being oppositional defiant disorder (ODD).
CONCLUSIONS: Siblings of people with ADHD have an increased risk of having the same disorder. The risk of having another psychiatric disorder markedly increases when the sibling also presents ADHD; this is especially true for ODD, substance use disorder and bipolar disorder.