Articles/Information

ADHD and Substance Abuse

Excerpted from an article in medscape.com written by Jay Giedd, MD titled "ADHD and Substance Abuse"

Parents are bombarded with conflicting information about attention-deficit/hyperactivity disorder (ADHD) and its treatment. Increased use of stimulant medications has sparked debates about whether more people are being appropriately recognized and treated or whether people are being overmedicated. A particularly powerful issue in these debates is the relationship between ADHD and substance abuse...

"Are people with ADHD more like to develop substance abuse?", is the least controversial and is answered in the affirmative by a plethora of epidemiologic data indicating that the diagnoses of ADHD and substance abuse occur together more frequently than expected by chance alone...

One of the studies was conducted by pre-eminent ADHD researcher Russell A. Barkley, PhD, whose team followed 147 clinic-referred children with ADHD for approximately 13 years. Parent and patient interviews were conducted at age 15 years and again in adulthood (19-25 years). Drug use/abuse details (alcohol, cocaine, amphetamines, all stimulants, marijuana, narcotics, sedatives, "others") and symptoms of ADHD and conduct disorder and were obtained and correlated with stimulant treatment in childhood and high school. Although there was no significant correlation between duration of stimulant treatment in childhood or high school and frequency of use of any drug in adulthood, the frequency of cocaine use in adulthood was higher among treated vs. non-treated groups...

"Are the stimulant medicines themselves addictive?" is being explored elegantly by the neuroimaging work of Nora Volkow. Research shows that the faster the rate of uptake, the greater the potential -- methylphenidate takes an hour to raise dopamine levels whereas cocaine takes seconds. One of the effects of stimulants is to block dopamine transporters, which are located on the presynaptic neurons and serve to remove the dopamine from the synaptic cleft. Using positron emission tomography, Dr. Volkow compared the potency of methylphenidate vs cocaine in blocking these transporters. To her surprise, methylphenidate was more potent than cocaine in blocking dopamine. A dosage of 0.5 mg/kg, a typical amount prescribed for children, blocked 70% of dopamine transporters.