ADHD in people with co-occurring substance use disorders

6. Considerations – Subgroups

6.3 ADHD in people with co-occurring substance use disorders

Clinical Questions

Although a specific question was not developed during consumer consultation, the importance of diagnosis and treatment of ADHD in people with co-occurring substance use disorder was raised during the public consultation process and was deemed by the GDG to be important for inclusion in this guideline.

Clinical practice gaps, uncertainties and need for guidance

People with ADHD who have co-occurring substance use disorders are an important subgroup requiring individual consideration. It is well established that ADHD is a risk factor for the development of substance use disorders and, conversely, that people presenting with substance use disorders have an increased risk of having ADHD, as noted in section 1.2 of the guideline (Groenman et al., 2013; van Emmerik-van Oortmerssen et al., 2012)(see also (Faraone et al., 2021; Ozgen et al., 2020).

Considerable debate exists internationally regarding the diagnosis and treatment of substance use disorders in individuals with ADHD and vice versa (Ozgen et al., 2020; Young, Bellgrove, & Arunogiri, 2021). Legitimate concerns exist regarding the diversion or misuse potential of stimulant medications in those with ADHD and substance use disorders. Although the GDG acknowledged that available evidence is insufficient to permit robust treatment recommendations in this group, it also recognised that guidance is warranted given the significant morbidity associated with people with substance use disorders.

Given the lack of strong empirical evidence, the International Collaboration on ADHD and Substance Abuse (ICASA) developed a consensus statement for the screening, diagnosis and treatment of ADHD and SUD (Ozgen et al., 2020). This statement comprised 37 statements, with the consensus reached for 36 of these.

This narrative review and the accompanying recommendations refer closely to this consensus statement, in combination with other available evidence.

Summary of narrative review

Prevalence

A childhood diagnosis of ADHD is an established risk factor for the development of substance use disorders in adolescents and adults (Groenman et al., 2013). Meta-analysis by Lee et al. of over 5400 people showed that those with ADHD were almost three times more likely to be nicotine-dependent and 50% more likely to develop a drug or alcohol disorder than individuals without ADHD (Lee, Humphreys, Flory, Liu, & Glass, 2011).

Meta-analysis by Groenman et al reported twofold greater odds of alcohol and nicotine-related disorders (Groenman, Janssen, & Oosterlaan, 2017) in people with ADHD. Sundquist et al. reported a more than threefold (Hazard Ratio of 3.34) increased risk of drug use disorders in children diagnosed with ADHD before 15 years of age, using data from a Swedish population-based cohort (Sundquist, Ohlsson, Sundquist, & Kendler, 2015).

Conversely, evidence also suggests that there is an increased prevalence of ADHD in those presenting with primary SUD compared with the prevalence of ADHD in the population. For instance, a meta-analysis by van Emmerik-van Oortmerssen reported that 23.1% of all individuals with substance use disorders met DSM-criteria for co-occurring ADHD (van Emmerik-van Oortmerssen et al., 2012).

Presentation and identification

Early detection of ADHD in drug and alcohol settings and, conversely, substance use disorders within mental health settings is critical to avoid the morbidity associated with coexisting ADHD and substance use disorders. For instance, it is established that ADHD has a negative influence on the course of substance use disorders, being associated with an earlier age of addiction, increased use of substances and higher rates of hospitalisation and higher relapse rates from addiction treatment (van Emmerik-van Oortmerssen et al., 2012).

Despite the negative consequences of having both conditions, there is a lack of systematic screening of substance use disorders in mental health services and ADHD in drug and alcohol services, resulting in poor detection and treatment of people in this subgroup (Ozgen et al., 2020; Young, Bellgrove, et al., 2021). As noted in section 2.2, ADHD screening measures explored in substance use disorder groups include the 6-item Adult ADHD Rating Scale (ASRS), which has acceptable sensitivity but not specificity (Kessler et al., 2005; Van de Glind et al., 2013).

For the detection of problematic drug and alcohol use in people with ADHD, two generally accepted screening instruments include the DAST (Drug Abuse Screening Test) and AUDIT (Alcohol Use Disorders Identification Test). Both were investigated for their construct validity and reliability in a population of adults with ADHD symptoms (n = 139). Results showed both the DAST and the AUDIT are acceptable screening instruments, respectively, for drug and alcohol use problems in adults with ADHD (McCann, Simpson, Ries, & Roy-Byrne, 2000).

ICASA’s international consensus statement for the screening and diagnosis and treatment of ADHD and substance use disorders recommends early detection, routine screening for at risk-use of substances and substance use disorders in adolescents with ADHD in primary care and mental health treatment settings, and screening for ADHD in adolescents entering substance use disorders treatment settings. Screening should follow best practice protocols for each disorder.

Assessment

For the diagnosis of ADHD in substance use disorders and vice versa, ICASA’s international consensus statement for the screening and diagnosis and treatment of ADHD and substance use disorders recommends that diagnosis for each should follow best practice protocols for each disorder separately and that diagnosis of co-occurring ADHD and substance use disorders should be performed by appropriately qualified health care specialists (see Principles), preferably using standardised structured diagnostic instruments (Ozgen et al., 2020).

Treatment

There is a lack of high-quality evidence (for example, RCTs and meta-analyses) regarding the pharmacological and non-pharmacological treatment of ADHD in people with substance use disorders (see Section 4 and Section 5). Nevertheless, the ICASA expert consensus statement recommends a multi-modal approach combining medication (particularly stimulants) and cognitive-behavioural therapy approaches. Where misuse or diversion is suspected, ICASA recommends consideration of non-stimulant treatment. Further, to minimise the risk of misuse and diversion, the use of long-acting, rather than short-acting, stimulants is recommended (Ozgen et al., 2020).

One RCT of 119 participants with ADHD and substance use disorders studied the impact of an integrated cognitive-behavioural therapy (CBT) intervention targeting both ADHD and substance use disorders, compared with CBT for substance use disorders alone (van Emmerik-van Oortmerssen et al., 2019). The integrated CBT intervention improved ADHD but not substance use disorder symptoms, suggesting the potential effectiveness of this integrated CBT for treating ADHD in this subgroup with concurrent CBT targeting substance use disorder symptoms (van Emmerik-van Oortmerssen et al., 2019) .

Myths around stimulant use and substance use disorders in ADHD

There are a number of myths regarding ADHD, substance use disorders and stimulant medication. One is that use of stimulant medication to treat ADHD causes or increases the risk of later developing substance use disorders. There is robust evidence that providing stimulant treatment for ADHD does not increase the risk of substance use disorders, compared with people with ADHD who do not access stimulant medication (Boland et al., 2020; Humphreys, Eng, & Lee, 2013). Stimulant treatment in people with ADHD can result in positive outcomes for those with co-occurring substance use disorders, including reduced substance use (Boland et al., 2020; Fluyau, Revadigar, & Pierre, 2021).

It is critical that these myths about ADHD and stimulant use are addressed by clinicians through accurate education, as they cause stigma, which can negatively impact on the self-esteem and self-worth of people with ADHD. Further, some state-wide regulations regarding the prescription of controlled drugs (which include stimulants) preclude or limit their use in people with ADHD and substance use disorders and may not reflect the evidence above. These myths and regulations can result in people with ADHD and their families not accessing the first line and most effective treatment for ADHD.

Recommendations

Clinical considerations for implementation of the recommendations

Given the high co-occurrence of substance use disorders and ADHD, clinicians working in addiction settings require expertise and training in ADHD. Those in mental health settings or settings, including people with high risk of ADHD, need to have experience in the identification of people with ADHD who have substance use disorders. Legitimate concerns exist regarding the diversion or misuse potential of stimulant medications in those with ADHD and substance use disorders.

If urine screening for illicit substances is used, clinicians should be aware of the limits of such screening tests and the potential for false positives/negatives and interactions with other medications. They should contextualise the interpretation of results with detailed patient histories.

Greater awareness that stimulant medications are rigorously controlled, safe medications and that long-acting formulations, in particular, are associated with no increased risk of future substance use disorders should help to reduce any fear or stigma around their use in alcohol and drug services and will ensure those with ADHD receive access to vital treatment. Greater interaction between addiction specialists and ADHD specialists is urgently needed.