Today, ADHD Stimulants; Tomorrow, Cocaine?

More than 80% of school age children with Attention Deficit/Hyperactivity Disorder (ADHD) respond positively to methylphenidate (i.e., Ritalin) with few side effects.  Some groups who are opposed to the use of medications for children with ADHD have raised public concern that giving this and other stimulants to children predisposes them to greater substance use and abuse when they become adolescents and adults.  Proponents of stimulant medications argue that methylphenidate is very dissimilar from cocaine and other addictive drugs because it clears the brain so slowly and as a result, possesses no potential for addiction. 
Barkley and co-authors followed 147 of their own patients for 13 years (up to age 25 years) to determine their own conclusions on this matter.  They found that children with severe ADHD or ADHD that co-existed with a conduct disorder, had higher risks for later cocaine use. These children were also most likely to be on stimulants.  When Barkley controlled for severity and associated conduct disorder, results showed treatment with a stimulant is not associated with later cocaine use.                                           

Over the past few years, twelve studies were published that examined a possible association between stimulant use for ADHD and later drug use or abuse.  Of these, eleven found no association.  Wilens and co-authors reviewed six of these studies very carefully and found that stimulant therapy in childhood actually has a protective effect – and reduces chances that students with ADHD will subsequently abuse drugs or alcohol.   Of the twelve published students, there was one outlier article which found that ADHD treatment in childhood increases risks for cigarette smoking, nicotine dependency, and cocaine dependence in adulthood.  Groups opposed to medicating children often only cite this study.  Careful scrutiny of this study by Barkley and his co-authors, demonstrated that there were flaws in the way the data were analyzed, accounting for its conflicting findings.        
   
(Barkley RA et al. Pediatrics 2003; 111(1):97-109.)
(Wilens TE et al. Pediatrics 2003; 111(1):179-185.)
– H.T.
 
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