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Brookhaven National Labs. has published many studies on the effects of methylphenidate (Ritalin) and cocaine on the brains: Volkow et al, Is methylphenidate like cocaine? Studies on their pharmacokinetics and distribution in the human brain. Arch. Gen Psychiatry 1995 Jun;52(6):456-63 The studies showed that although cocaine does bind to dopamine receptors in the basal ganglia, similarly to methylphenidate, cocaine's clearance from the brain was over 3 times faster (20 min. versus 90 min). Also, there are two stereoisomers of methylphenidate present in commercial Ritalin and generic methylphenidate. The R-isomer has been shown to stimulate dopamine in the frontal lobes and to inhibit the reuptake of norephinephrine. The L-isomer is believed to cause a "high." When the 50:50 isomer mixture (racemic methylphenidate) is taken orally, most of the L isomer converts to the D-isomer in the gut. Abusers need to snort racemic methylphenidate in order to get a high from the commercial product. Does anyone know if methylphenidate has any effect on PD symptoms? I am not aware of any such study. Also, I am very interested to known if anybody in the network has been diagnosed with both ADHD and PD. Fiona Geiser ([log in to unmask]) (By the way, I have a Ph.D. in organic chemistry and I have also been diagnosed with Attention Deficit Hyperactivity Disorder (ADHD). I am curious about the similarities of PD and ADHD medications. For instance, the active metabolite in selegiline is D-amphetamine. D-amphetamine is prescribed as an alternative stiumulant for use in ADHD. Interesting connection. Neuroimaging studies have shown the cocaine abusers deplete dopamine neurons in the basal ganglia over time.) ---------- From: Parkinson's Disease - Information Exchange Network on behalf of Maggie Salls Sent: Sunday, May 05, 1996 11:21 AM To: Multiple recipients of list PARKINSN Subject: cocaine and ritalin I just caught the tail end of two reports this last week on NPR which led me to believe that cocaine flooded the brain with dopamine-like agents. Ditto with Ritalin. Is there anything here that has relevance to PD? Can't be more specific as I was in a car on a big highway and didn't get the whole of the story. Probably reported on All Things Considered or Morning Edition. Maggie Salls