Definitely Not Maybe: A Paradoxical Effect of Ritalin on Deprivation-Induced Hyperactivity


Ian McLaughlin

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Background: Stimulant medications -- Ritalin being the oldest on the market -- have been noted for their paradoxical effects: Stimulant medication generally decreases hyperactivity in people with ADHD but increases activity in those without the disorder. This paradoxical effect has been seen in rats selectively bred to be high voluntary runners as a model of the hyperactive dimensions of ADHD; Ritalin lowers running of High Runner mice. Food deprivation also increases rats? running and hyperactivity. We set out to see whether the ?paradoxical effect? of Ritalin can extend to food deprivation-induced hyperactivity (DIH) in Rats. Design: Thirteen normal adult male rats were placed in a running wheel for two hours a day under four different conditions: normal, drug only, food deprived only, and food deprived and given drug. Results: Experimentally, food deprivation and Ritalin increased running additively ? i.e. Ritalin increased hyperactivity equally in both well-fed and food deprived rats. However, when individual differences in DIH were examined, a negative correlation between the magnitude of DIH and Ritalin?s effect was observed. That is, Ritalin suppressed running in rats especially vulnerable to food deprivation-induced hyperactivity. Conclusion: Ritalin may exacerbate the negative symptoms of anorexia. However, in those most vulnerable to deprivation-induced hyperactivity, Ritalin may decrease hyperactivity.


Nancy Dess




Ford Research Endowment

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