ADHD: Attention-Deficit/Hyperactivity Disorder; OUD: Opioid Use Disorder; MOUD: Medications for Opioid Use Disorder; OTP: Opioid Treatment Program; SUD: Substance Use Disorders; UDS: Urine Drug Screen; ASRS-5: ADHD Self-Report Scale for DSM-5; ASRS v1.1: ADHD Self-Report Scale Version 1.1

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopment disorder characterized by functional impairment due to inattention, hyperactivity, and impulsivity [1]. The condition is commonly diagnosed among people with substance use disorders (SUD) [2–4]. The global prevalence of adult ADHD is less than 3% but increases to over 20% in patients with opioid use disorder (OUD) [5,6]. Medications for OUD (MOUD) – including methadone, a long-acting semi-synthetic opioid—are the gold standard treatment for the condition, shown to reduce mortality, illicit drug use, and infectious disease transmission [6,7].

Comorbid psychiatric disorders have been shown to negatively impact OUD treatment outcomes, including increased risk for return to drug use and medication nonadherence [8,9]. Prior studies have shown an association between ADHD and comparatively worse methadone treatment outcomes in patients with OUD, including retention in care [1,10,11].

Researchers have evaluated patients with ADHD who were already well-maintained on MOUD treatment for greater than six months, and found that increased impulsivity was associated with worse OUD treatment outcomes [1].

Additionally, a previous study assessed patients who had reported ADHD diagnoses and OUD, and found that from 2007 to 2017, the prevalence of ADHD diagnoses increased from 4.6% to 15.1% and the rate of ADHD pharmacotherapy increased from 42.6% to 51.8% among patients with OUD [3]. Despite these findings, no specific guidelines exist for managing patients with both ADHD and OUD, indicating the need for further research on evidence-driven treatment strategies in this high-risk population [12].

This project’s purpose is to add to existing data in this field by characterizing the prevalence of screening positive for ADHD by way of a validated symptom reporting scale, which was uniquely delivered to patients when initiating treatment for OUD at an opioid treatment program (OTP) and evaluate the association between screening positivity and treatment retention.

This is a retrospective cohort study of individuals seeking methadone treatment at a Denver-based outpatient opioid treatment program. All individuals aged 18 years or older with OUD presenting for an intake appointment between October 1, 2023, and February 28, 2024 were included in the analysis. Individuals completed a voluntary survey which included demographic information and an ADHD screening instrument that was implemented as part of a quality improvement project during intake. A referral for a more in-depth evaluation of ADHD symptoms was provided if indicated. As part of the intake process, a urine drug screen (UDS) was performed. Stimulant use was defined as the presence of methamphetamine or cocaine in a patient’s UDS. Any individuals who did not complete the survey were excluded from the analysis.

The six question ADHD Self-Report Scale for DSM-5 (ASRS-5) was used for the ADHD screening. The ASRS-5 is a newer, shorter scale than the original ADHD Self-Report Scale Version 1.1 (ASRS v1.1) [13]. Respondents are asked to indicate how often a symptom occurred in the prior six months by answering: never, rarely, sometimes, often, or very often. Each answer is converted to a numerical score from 0 to 4, respectively (never=0 and very often=4). The final score is the sum of each response. We defined a positive screen as a score 14 or higher out of 24 maximum points.

The primary outcomes of interest were the proportion of individuals screening positive for ADHD and duration retained in care (<2 months vs. >2 months). Retention in care was measured at the 2-month cutoff point based on previous intraorganizational data which demonstrated a drop in treatment engagement for those who did not remain in care past 2 months. All data were analyzed using descriptive statistics and chi square tests on Microsoft Excel.

A total of 66 individuals who completed the survey were included during the study period with 50% identifying as female. The range of ages were between 18 to 64, with 37.9% of respondents between ages 25 to 34 and 42.4% between 35 to 44. Of the 29 individuals reporting race, 86.2% were White. Of the 30 individuals reporting ethnicity, 36.7% were Hispanic or Latinx. All patients completed the ASRS-5 during their intake appointment. Using the ASRS-5 screening tool, 36 (54.5%) individuals screened negative for ADHD and 30 (45.5%) screened positive. There were no statistically significant differences in UDS positivity for stimulants between the individuals who screened positive for ADHD compared to those who screened negative at 63.3% and 63.9%, respectively (P>0.05; Table 1).

With regards to the effect of screening positive for ADHD on retention in care, 16 (53.3%) individuals who screened positive for ADHD left care within 2 months of intake compared to 15 (41.7%) who screened negative (P>0.05; Table 2). A greater proportion of

individuals who screened negative for ADHD remained in treatment for >2 months compared to those who screened positive for ADHD (58.3% and 46.7%, respectively), although these differences did not reach statistical significance (P>0.05).

Our study showed that nearly half of patients seeking methadone for OUD screened positive for ADHD based on the ASRS-5 screening tool. This suggests a much higher prevalence of ADHD in patients seeking OUD treatment compared to the general population. It is also higher than previous studies on individuals with OUD which showed a prevalence of ~20% [4]. There are several hypotheses as to the factors associated with OUD and ADHD comorbidity. For one, direct symptoms of ADHD, such as impulsivity and sensation seeking, might be determinant factors of vulnerability to substance experimentation. The impulsivity may also affect likelihood of treatment failure in OUD, as seen in the trend in care retention in our study. There is growing evidence that, in general, individuals with ADHD tend to have more severe SUD, with one particular study demonstrating an increased drug dependence complexity and severity in treatment-seeking SUD patients who screen positively for ADHD symptom status [14,15].

The ASRS-5 screening scale is short, easily scored, and validated to detect nearly all people who met diagnostic criteria for ADHD in clinical interview among those in the general population and those seeking specialty treatment [13,16]. It can be easily implemented in clinical practice given its brevity, and its high sensitivity allows for few false positives. To our knowledge, there are no studies validating its use in individuals with SUD. There may be an overlap between some symptoms associated with opioid withdrawal and ADHD which can make it hard to differentiate between the two. However, a previous study has similarly demonstrated the impact of ADHD on OUD treatment non-adherence, underscoring the importance of screening and management for this condition [1].

Retention in OTP is associated with reductions in risk for all cause and overdose mortality in individuals with OUD. One meta-analysis showed the rate of all-cause mortality during opioid agonist treatment (OAT) was markedly lower than the rate seen during time out of OAT. Rates of all-cause mortality were also higher in the 4 weeks after OAT cessation, and remain elevated throughout the remainder of time out of treatment [6].

There are several limitations to this study. Our small sample size may not reflect the true prevalence of ADHD within the population of individuals with OUD seeking methadone treatment. While we did not keep track of the number of individuals who did not complete the survey, it is possible that those who were unable to complete the form had more severe symptoms of ADHD or opioid withdrawal and would have different rates of retention in the OTP. The ASRS is a screening tool rather than a diagnostic tool, and some patients who screen positive could ultimately be determined not to have the condition. An assessment by a psychiatrist with collateral information would be recommended for further evaluation and to validate the use of the ASRS-5 screening tool in this population. Additionally, although there were no significant differences in stimulant use by UDS among those who screened positive for ADHD compared to those who screened negative, the use of stimulants can affect both memory and attention, thereby affecting the results of the ASRS screen. Finally, our use of OTP retention is an imperfect proxy outcome that may overlook important clinical events among our patients.

Overall, this study demonstrates a high proportion of patients with OUD seeking methadone treatment who report ADHD symptoms, as well as a global decline in care engagement after two months. Our results highlight the utility of an ADHD screening tool to identify individuals with possible dual diagnoses who may benefit from further clinical evaluation and additional resources to support them in remaining in treatment. Future steps could include validating the use of the ASRS-5 screening tool in individuals with OUD, as well as evaluating the impact of initiating ADHD treatment for individuals with OUD and a confirmed diagnosis of ADHD, on retention in care and other outcomes.

None.

All authors contributed equally.

The authors have no conflicts of interest to disclose.

This project was supported in part by a grant from the Colorado Department of Public Health and Environment Practice-Based Health Education Program.

This study was reviewed and approved by the Colorado Multiple Institutional Review Board at the University of Colorado Anschutz Medical Campus.