Diagnosis of Attention Deficit Hyperactivity Disorder in Adults with Intellectual Disability: How Are We Doing with Diagnosis and Treatment?

Abstract

Introduction Prevalence of ADHD among people with intellectual disability (ID) is higher than people without intellectual disability (Reilly & Holland 2010), however it appears to be underdiagnosed (Rose et al 2009). Objectives Describe the prevalence of ADHD in ID psychiatric clinics and patient characteristics in Surrey, UK. Method Patients' records in ID psychiatric clinics were audited. Results 14 patients attending ID clinics had a diagnosis of ADHD. Age range was 18 to 32. 85% were male. Prescribed ADHD medications were Concerta XL, Medikinet XL, methylphenidate, atomoxetine and clonidine. 21% were on combination of two ADHD medications. 43% of the patients were also on other psychotropic medications. 36% of patients with ADHD also had a diagnosis Autism. 42% had another comorbid mental disorder. Conclusions Given the prevalence rate for ID (1.03%) and ADHD (6.8%), nearly 400 individuals with ID should have a diagnosis of ADHD in this catchment area. Presence of only 14 individual with ADHD shows that ADHD is extremely under diagnosed and under treated within ID population. This raises the issue whether patients are treated with psychotropic medications and psychological methods for behavioural and mental health issues due to under diagnosis of ADHD. Diagnosis of ADHD and complexities of such diagnostic processes among people with ID may be some of the reasons for under diagnosis (White et al 1995, Reiss et al 1982). Screening tools and increasing awareness may be needed to detect ADHD symptoms in this group of people when psychiatric diagnoses are often challenging.