A Study of the Impact of Hemophilia and Its Treatment on Brain Development, Thinking and Behaviour in Children With Hemophilia

Inclusion Criteria: - Male child or young adult (ages 1:0-3:6 and 4:0-21:11 years with diagnosis of congenital hemophilia A or B, any severity, with or without inhibitors - Parent able and willing to provide consent, and young adult with hemophilia (age 18-21) able to provide consent; children (ages 7-14) and adolescents/young adults (ages 14-17) able and willing to provide assent based upon local institutional policies - Parent able and willing to complete neurodevelopment and cognitive parent reported scales during comprehensive or other Hemophilia Treatment Center visit for about 45-60 minutes in English or Spanish depending on age group) - Children, adolescents and young adults with hemophilia (ages 1-21) able to participate in assessments of development and intelligence for about 40-45 minutes and adolescents and young adults (age 11-21) with hemophilia able and willing to complete additional self-assessment scales for about 30-45 minutes during comprehensive or other elective visit for in English or Spanish (depending on age group) - Provision of informed consent before the start of any study-related activities Exclusion Criteria: - Patient aged 3:7-3:11 years (43-47 months) - Prior participation in the study - Prior neurocognitive screening with the same or related instruments in the prior 6 months - Patients with hemophilia or their caregivers for whom test measures may be culturally inappropriate - Patients with hemophilia with known history of alcohol or substance abuse - Patients with hemophilia who have used opiates in the past 24 hours or other illicit drugs within the past 48 hours - Patients with hemophilia currently experiencing an acute bleed that has not resolved - Patients with hemophilia with recent head injury or concussion within the past 4 weeks - Concurrent diagnosis of another bleeding or thrombotic disorder - Mental incapacity, unwillingness or language barriers precluding adequate understanding or cooperation