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For the study, Thomas Spencer, M.D., the assistant chief of the Pediatric Psychopharmacology Research Program at Massachusetts General Hospital, and colleagues enrolled 37 young adults (aged 18 to 30) with ADHD who reported a feeling of euphoria when taking stimulants. The participants were randomly assigned to take either placebo or 50 mg naltrexone in the morning along with an extended-release methylphenidate formulation taken in the morning and afternoon (up to 80 mg/day).
At baseline and three and six weeks later, the participants were asked to take a drug likeability test, where they answered questions about how good they felt after taking their medications. On the days they were given the drug likeability test, the participants took either an immediate-release methylphenidate pill in the morning or afternoon instead of their regular extended-release medication.
Spencer and colleagues observed that naltrexone significantly diminished the euphoric effect of immediate-release methylphenidate during the first three weeks of the study (the titration phase) but not during weeks 4 to 6 (the maintenance phase) of the study. Research has shown that stimulants pose the most risk for abuse when introduced abruptly and unevenly, such as the first few weeks of treatment when the optimal dose is being determined. “It is possible that the experience of euphoria attenuated because the study subjects only had mild euphoria at outset. Our nonsignificant effect for euphoria at week 6 should be viewed with caution due to the possibility of a floor effect, which would have reduced statistical power,” they wrote.
“[T]his double-blind, randomized clinical trial showed that treatment with naltrexone diminished the euphoric effect of immediate-release methylphenidate during the initial methylphenidate titration period of heightened vulnerability,” Spencer and colleagues continued. “If confirmed, these findings could lead to the development of a nonaddictive form of stimulant treatment for ADHD, which could facilitate access to an effective ADHD treatment.”
For related information, see the Psychiatric News article “Six-Question Screen for ADHD Developed for Adults.”
