Diversion and Abuse of Prescribed Methylphenidate – A Survey of an Outpatient Clinic for Adult Persons with ADHD

Dear Editor,

Methylphenidate (MPH) is currently the first-choice medication of adult ADHD, followed by lisdexamfetamine [1]. In Germany, only extended-release MPH (ER- MPH) is licensed for adults. As a norepinephrine-dopamine reuptake inhibitor (NDRI) MPH has the potential to induce euphoria, drive enhancement, and other psychotropic effects of amphetamine-like stimulants, especially after intranasal and intravenous administration [2]. Therefore, there are concerns that MPH-treated patients might abuse their medication, might feign ADHD symptoms in order to receive a prescription, and/or might aggravate ADHD symptoms in order to receive a higher dosage [3]. Moreover, especially according to studies from the USA, ADHD patients treated with MPH at considerable rates reported of diverting (e. g. 11 and 44%; [3]) and abusing their medication (e. g. 14% to 29% [3] [4] [5]).

This study aims at characterizing stimulant-treated German adult ADHD patients with regard to diversion, non-medical use and abuse of prescribed psychostimulant medication. The study was conducted in an ADHD clinic as part of a psychiatric university hospital. There, patients undergo an extensive diagnostic process including medical history; a semi-standardized interview (DSM-IV criteria); check of ADHD symptoms during childhood, e. g. based on school reports; assessment with standardized psychometric tests; and computerized neuropsychological measurements of attentional, executive and memory skills (detailed description see [6]). In case of a diagnosis of ADHD, counseling appointments are offered and medication is prescribed; in some cases, patients are referred back to the referring physician. Persons with current manifest neurological or addictive diseases are excluded from diagnostics and treatment.

The present investigation utilized a self-developed questionnaire containing 14 questions with predefined answering options. A primary version of the questionnaire had been used on a pilot sample and checked for comprehensibility of the questions, as the patients had to complete the questionnaire completely independently. Adult patients with a current ER-MPH prescription and sufficient knowledge of the German language were asked for participation at their regular visit to the clinic (at least every 3 months for most patients). Patients were informed that their participation was strictly anonymous, and that they should return the questionnaire using a post box in the waiting area of the clinic. The study was approved by the Ethics Committee of the Medical Faculty of the University of Duisburg-Essen, Germany (21-10165-BO).

From 2018 to 2020, 918 adult patients attended the ADHD clinic. Of these, 190 patients received stimulant prescription in the ADHD clinic. Questionnaires from 100 participants were collected (response rate 52.6%). Respondents were mainly male (n=60; 8 responses missing). The average age was 33.2±11.7 years. Patients had been in treatment at the ADHD clinic for an average of 5 years. Self-reported abuse and diversion of prescribed stimulant medication are shown in [Table 1]. By far the most frequent behaviour violating treatment protocol was dose increase by patients for enhanced symptom reduction, which was reported by 23 patients, including ten who had done so at five times or more during lifetime. Indications of ER-MPH abuse were reported by a small minority (increase of dosage to get “kick” n=3; non-oral application n=4; prescription from several doctors n=2). Nine patients reported on ER-MPH diversion during lifetime, two of them during the last 12 months. The lifetime prevalence of diversion, medication abuse/misuse or increase of dosage was 30%.

Table 1 History of in-treatment psychostimulant abuse and diversion (n=100).

	Lifetime prevalence	Lifetime frequency>= 5 times	Prevalence last 12 months
Diversion	9	1	2
Took less than prescribed, to divert the surplus	0	0	0
Gave ADHD medication to others	9	1	2
Abuse of Medication	10	5	4
Voluntarily overdosed to get a “kick”	3	2	3
Took medication not in tablet form	4	3	-*
Aggravated symptoms to get higher doses	1	0	0
Purchased additional MPH	5	1	2
Received MPH receipts from several physicians	2	1	1
Took more MPH for more symptom reduction	23	10	20
up to 10 mg	8	*	*
20 mg	8	*	*
30 mg	4	*	*
40 mg	1	*	*
not specified	2	*	*
Any non-medical use, abuse or diversion	30	12	21 **

*Not asked. *at least 21 patients (change of the route of application not asked regarding the last 12 months).

The lifetime rate of stimulant diversion and abuse in the present study was lower than reported in most other studies, especially those investigating adolescent and student samples in North America. We attribute this result to the extensive diagnostic process and the strict treatment procedures, e. g. therapy contracts, regular clinical evaluations, prescription of extended-release methylphenidate [7]. It is worth noting that after extensive diagnostics, only about 50% of patients who presented to the ADHD clinic receive the diagnosis of ADHD [6]. Reducing concerns about diversion and abuse by using such diagnostic and treatment procedures might help to prevent underprescription of MPH and other stimulants to ADHD [8] [9].

The present survey was conducted strictly anonymously to reduce the risk that effects of social desirability and fears of negative consequences might influence the answers to sensitive questions. Due to this, the information provided is considered as valid. However, the participation rate was just a bit more than half of the treated patients. Hence, it could not be ruled out that patients not returning their questionnaires had a higher prevalence of misuse and diversion than patients participating in the study. In addition, the survey did not ask for additional patient characteristics, which could have compromised anonymity, e. g. education or employment. Therefore, generalizability of results within the present and to other patient populations cannot be fully determined.

Publication History

Received: 25 September 2024

Accepted after revision: 21 February 2025

Article published online:
27 March 2025

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