ADHD in dependent drug and alcohol users: Prevalence, Correlates, and Implications for Diagnosis and Treatment

The estimated global prevalence of childhood Attention Deficient and Hyperactivity Disorder (ADHD) is in the region of 5 to 10% (Skounti et al 2007; Polancyzk et al 2007) and there is evidence that between one and two thirds of childhood ADHD persists into adulthood (Wender et al, 2001; Faraone et al 2004). The prevalence of adult ADHD is not well documented but studies in Europe, the United States and the Middle East suggest that between 1 and 6% of adults may have adult ADHD (Kessler et al 2006; Carroll & Rounsaville, 1993). Many adults with ADHD remain undiagnosed.

ADHD has been associated with substance use disorders. The disorder is associated with the earlier onset substance use as well as higher frequency and increased chronicity (Levin et al 1998; Fayyad et al 2007). Between 20 and 40% of substance using populations in some countries have been found to display symptoms of ADHD (Levin et al 1998; Schubiner et al 2000). However, data on the prevalence of ADHD among Australian substance users is limited and due to differences between the tools used to screen for adult ADHD, comparability across studies is low.

In 2008, NDRI, along with NDARC and the School of Psychology and Speech Therapy at Curtin University were invited to join a consortium of experts in ADHD and Substance Use which is currently operating across 15 countries. The consortium (International Collaboration on ADHD and Substance Abuse (ICASA)), is coordinated by the Trimbos Institute, Netherlands Institute of Mental Health and Addiction (a WHO Mental Health Partner) and being involved with this partnership will put Australia alongside other countries participating at the forefront of this research.

NDRI was successful in securing funds from Curtin University for WA and NSW to take part in the preliminary screening component of the international study. Dr Sharlene Kaye, from NDARC, is coordinating the initiative and data collection in NSW, Dr Susan Carruthers and Steve Allsop are responsible for the WA arm of the investigation. This involves the interviewing of approximately 600 recent treatment entrants (300 in NSW and 300 in WA), collecting baseline demographic data, a substance use history, a history of childhood and adult mental health diagnoses and treatment, and a driving history to assess the level of risk participants are prepared to take on a daily basis. The study includes to collection of saliva samples via non-invasive means for DNA analysis. Samples are to be analysed in Spain and stored at the National Institutes of Health in the USA. Depression and anxiety are assessed using the DASS 21 and screening for ADHD is conducted using the ASRS v1.1.