Previous research has shown that behavioural changes in rats treated with methylphenidate (Ritalin), a commonly prescribed medication for attention-deficit hyperactivity disorder (ADHD), persist after treatment discontinuation.
In a study in the Journal of Neural Transmission
(online, 23 January 2017), the same researchers studied the effect of the drug on neurochemistry in adolescent rat brains.
They found that three months of a high-dose regimen of methylphenidate (30mg/kg MP for the first hour; 60mg/kg for the remaining 7 hours), increased dopamine-transporter and -receptor binding in multiple brain regions, some of which correlated with behavioural changes. However, when rats underwent a one-month abstinence period following methylphenidate exposure, these differences in dopamine binding were not observed.
The researchers say the findings suggest the effects of methylphenidate on dopamine neurochemistry are likely to be reversible. But, they say, it is still concerning given the role of these receptors in multiple psychiatric diseases and the increasingly common use of non-prescribed methylphenidate as a cognitive enhancer.
 Robison L, Ananth M, Hadjiargyrou M et al. Chronic oral methylphenidate treatment reversibly increases striatal dopamine transporter and dopamine type 1 receptor binding in rats. J Neural Transm 2017. doi: 10.1007/s00702-017-1680-4