Compliance with methylphenidate treatment and drug abuse of adults with attention deficit hyperactivity disorder (ADHD)

INTRODUCTION: Attention deficit hyperactivity disorder (ADHD) is a neuropsychiatric disorder characterized by symptoms of inattention with or without evidence of impulsivity/hyperactivity. In 80% of the children with ADHD, symptoms persist through adolescence and adulthood1 . Compliance with treatment is an important factor for the outcome and patients’ health. When related literature is revised, it is seen that compliance with treatment in ADHD is studied in children2 . It is also important to mention that, though stimulants are highly effective as first line pharmacotherapies for ADHD, they pose a risk for abuse3 . Patients with ADHD have a high risk for substance abuse. It was found that adults with ADHD had significantly higher rates of drug as well as comorbid drug and alcohol use disorders than non-ADHD adults4 . There are many studies conducted in order to determine comorbid diagnoses with ADHD. According to one study, adults with ADHD, compared with adults without ADHD, had significantly more current Axis I disorders5 . The purpose of the present study is to determine the prescribed methylphenidate use routines of adult patients diagnosed with ADHD. How strictly these patients follow the prescribed doses and timings will be evaluated in order to see their compliance with methylphenidate treatment. The study also aims to understand the prevalence of comorbid conditions and drug abuse of these patients.

METHOD/PROCEDURE: 42 out-patients followed at the ADHD treatment program in the Istanbul Medical Faculty Hospital Psychiatry Department were enrolled in the study. Before confidential semi-structured face to face interviews, participants were informed and consent provided. After completing a socio-demographic form, participants were asked to provide information about the details of their disorder, their medicines for ADHD and details of other existing diagnosed disorders if any. Details like type of medication, age of patient at the time of their first diagnose of ADHD, and drug use periods were investigated. Patients were asked whether they use the ADHD medicine differently from their prescription in terms of either the dosage or the timing. Participants also provided information about their lifetime use of various illicit and licit drugs including tobacco, cannabis, inhalants, synthetic cannabinoids, heroin, cocaine, amphetamines, hallucinogens, any type of medicine in order to experience intoxicating effects and any other drug not already mentioned. Patients over 18 years of age who had been prescribed methylphenidate for ADHD for at least 3 months and volunteered to participate were included in this study.

RESULTS: A total of 42 patients diagnosed with ADHD participated in the study, 11 (26.2%) female and 31 (73.3%) male. The mean age of the participants was 22.45 years±5.1 (range 18-43). 39 (92.9%) of the participants were single and 3 (7.2%) were either married or engaged. 4 (9.5%) of the participants were secondary school graduates, 21 (50%) of them were high school graduates, 16 (38,1%) had graduated from either vocational school or undergraduate program, and 1 (2.4%) had a higher education degree. 52.2% (n=22) of the participants were students and 2 of these students had part-time jobs; 11 (26.2%) participants were employed and 9 (21.4%) were neither students nor employed. Of the participants, 18 (42.9%) had been diagnosed with ADHD at the age of 12 or younger, 6 (14.3%) had been diagnosed between the ages 13-17 and 18 (42.9%) had been diagnosed at the age of 18 or over. Participants were also asked to report the main ADHD feature as ‘only attention’, ‘only hyperactivity/impulsivity’ and ‘both attention and hyperactivity/impulsivity’. 26 (61.9%) of the participants did not have any additional diagnosis whereas 16 (38.1%) had at least one additional diagnosis. 3 of these 16 participants had 2 comorbid diagnoses (in all three cases, the third comorbid disorder was a depressive disorder). The distribution of the comorbidities: Depressive disorders (n=6), Obsessive Compulsive Disorder (n=3), Anxiety Disorders (n=2), Mild MR(n=2), Borderline PD (n=2), Tic Disorders (n=1), Conversion (n=1), Conduct Disorder (n=1) and Dyslexia (n=1). 36 (84%) of the participants had taken their medication on their own whereas 7 (16%) of them had taken them under somebody else’s supervision. 15 (35.7%) of the participants reported using the medicine differently (in timing) than prescribed; the distribution being as follows: 4 (9.5%) were ‘not using it on the weekends’, 4 (9.5%) were ‘using it periodically’, 11 (11.9%) were ‘ using it only as needed’ and 2 (4.8%) were ‘frequently missing doses’. 16 (61.9%) reported changing the doses when taking the medicines they were prescribed: 4 (9.5%) were ‘using more than the doctor’s prescription’, 1 (2.4%) was ‘using less than the doctor’s prescription’ and 11 (26.2%) were using ‘as much and frequently as they feel necessary’. 14 out of the 15 participants who tended to use their medicine differently (in timing) than prescribed were among those who took their medication on their own; whereas only 1 participant who used the medicine differently (in timing) than prescribed was taking it under someone else’s supervision. From a different point of view, 14 (32.6%) of the 36 participants who had taken their medication on their own were prone to use medicine differently than their prescriptions, and this constitutes 33.3% of the total participants. 11 (26.1%) of the participants reported using illicit/licit drugs (to experience intoxication effects) at least once in their lifetime. 6 participants used only one type of illicit/licit drugs whereas the remaining 5 used more than one type of illicit/licit drugs. The distribution of the drugs: Cannabis (n=10), Synthetic Cannabinoids (n=2), Cocaine (n=1), Amphetamines (n=1), Hallucinogens (n=1), Licit drugs for intoxication purposes (n=3).

DISCUSSION: Compliance with treatment is an important factor for the outcome and patients’ health. The present study intended to determine the compliance with methylphenidate treatment in adults with ADHD. The results suggest that the participants with ADHD tend not to use their medications properly, especially the ones who take their medications independently. 15 participants were not following their prescription schedule and 14 of these participants were among those who were taking their medicines independently. Similarly, 16 participants tended to change the dose of their medication based on their needs. It is thought that there is a high possibility of increase in compliance of medication treatment when the patient is supervised or given the prescribed dose of medicine by someone else. When symptoms are taken into consideration, adults with ADHD report mostly ‘attention’ problems, followed by combined type; and least reported is ‘hyperactivity/ impulsivity’ with the ratios 47.6%, 42.9% and 9.5%, respectively. Similarly findings of another study show that patients in the predominantly hyperactive/impulsive group represent a small rate among the total number of participants5 . There is a high possibility that the hyperactivity/impulsivity problems common in childhood ADHD tend to fade, while in adults, inattention problems arise or stand out over time. Lifetime substance use was high in the sample group. Our findings show that ADHD patients are a non-negligible risk group for lifetime substance use with the ratio of 11 (26.1%). A 38.1% comorbidity rate seems lower than the previous reports in the literature. Depression was the most common comorbid diagnosis, and this finding was compatible with the literature. The main limitation of the present study was its reliance on self-report as the primary method of assessment. Although prescribed doses and medications were cross-checked from patient files, it was not feasible to cross-check the use of illicit drugs or drifts from the prescribed methylphenidate using routines that the participants reported. It is possible that participants underreported the frequency of drug use or compliance of treatment due to the socially undesirable nature of these behaviors. The scope of the present study will be enlarged in a subsequent study as data collection continues with new incoming patients.