Should you prescribe a stimulant to treat attention and hyperactivity problems in teenagers and adults with a history of substance abuse? Evidence suggests that using a stimulant to treat attention-deficit/hyperactivity disorder (ADHD) may place such patients at risk for stimulant abuse or for relapse into abuse of other substances. But a stimulant may be the only option for patients whose ADHD symptoms do not respond to alternate medications, such as antidepressants.
Growing numbers of adults are being treated for ADHD. Because substance abuse problems are common in adults with ADHD (Box 1 ),1-3 prescribing an antidepressant instead of a stimulant in some cases may be prudent. Consider the following factors when choosing ADHD therapy for patients with a history of substance abuse.
Prevalence of stimulant use and abuse
In the United States, more than 95% of medications prescribed for children and adults with ADHD are stimulants—usually methylphenidate.4 Stimulant use has increased as more children and adults are diagnosed with ADHD. Methylphenidate prescriptions increased five-fold from 1990 to 1995.5 Visits to psychiatrists and physicians that included stimulant prescriptions grew from 570,000 to 2.86 million from 1985 to 1994, with most of that increase occurring during visits to primary care and other physicians.6
When used as prescribed, methylphenidate is safe and effective for treating most children and adults with ADHD. Methylphenidate’s pharmacologic properties, however, are similar to those of amphetamines and cocaine (Box 2, Figure 1),7,8 which is why methylphenidate is a schedule-II controlled substance.
Published data. Fifteen reports of methylphenidate abuse were published in the medical literature between 1960 and 1999,7 but little is known about the prevalence of stimulant abuse among patients with ADHD. Banov and colleagues recently published what may be the only data available, when they reported that 3 of 37 (8%) patients abused the stimulants they were prescribed for ADHD.9 The three patients who abused stimulants had histories of drug and alcohol abuse at study entry. In all three cases, stimulant abuse did not develop immediately but became apparent within 6 months after the study began.
In a study of 651 students ages 11 to 18 in Wisconsin and Minnesota, more than one-third of those taking stimulants reported being asked to sell or trade their medications. More than one-half of those not taking ADHD medications said they knew someone who sold or gave away his or her medication.10
Stimulant theft, recreational use. Methylphenidate has been identified as the third most abused prescribed substance in the United States.11 It was the 10th most frequently stolen controlled drug from pharmacies between 1990 and 1995, and 700,000 dosage units were reported stolen in 1996 and 1997.12
As many as 50% of adults with ADHD have substance abuse problems (including alcohol, cocaine, and marijuana), and as many as 30% have antisocial personality disorder (with increased potential for drug-seeking behaviors).1 Compared with the general population, persons with ADHD have an earlier onset of substance abuse that is less responsive to treatment and more likely to progress from alcohol to other drugs.2
The elevated risk of substance abuse in ADHD may be related to a subtle lack of response to normal positive and negative reinforcements. Hunt has outlined four neurobehavioral deficits that define ADHD.3 Besides inattention, hyperarousal, and impulsiveness, he proposes that persons with ADHD have a reward system deficit. They may gravitate toward substance abuse because drugs, alcohol, and nicotine provide stronger rewards than life’s more subtle social interactions.
The popular media have reported recreational use of methylphenidate—with street names such as “R-Ball” and “Vitamin R”—among teens and college students.13 Illegal stimulants are perceived to be easily accessible on college campuses, but no data have been reported.
The use of stimulant medication for ADHD patients with substance abuse problems remains controversial. For such patients, this author reserves stimulant medication for those:
- whose ADHD symptoms have not responded adequately to alternate treatments
- who have been reliable with prescription medications
- and whose functional level is seriously impaired by their ADHD.
Antidepressants vs. stimulants
Although few well-designed controlled studies have been published, four antidepressants appear to be reasonably equivalent in effectiveness for adults with ADHD and do not carry potential for stimulant abuse.14
Desipraime, bupropion, venlafaxine, and the experimental drug atomoxetine (Table 1) all increase norepinephrine at the synapse by inhibiting presynaptic reuptake. Though dopamine has traditionally been considered the neurotransmitter of choice for ADHD treatment, norepinephrine may be equally potent.
Impulse control center. Several lines of research have recently established a connection between the prefrontal cortex, norepinephrine, and ADHD.15 This evidence suggests that the prefrontal cortex plays a major role in inhibiting impulses and responses to distractions: