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Nicotine as Good as Ritalin on Core Measure of Attention Deficit/Hyperactivity Disorder: Presented at SFN

By Roberta Friedman, PhD

NEW ORLEANS, LA -- November 13, 2003 -- Nicotine serves as well as the commonly prescribed drug methylphenidate (Ritalin) on measures of motor inhibition taken in teens with attention deficit/hyperactivity disorder (ADHD).

Investigators of a small study presented here November 8^th at the Society for Neuroscience 33^rd Annual Meeting, used the finding to suggest that smoking in people with ADHD is an attempt at self-medication.

Alexandra Potter, PhD, postdoctoral fellow, Clinical Neuroscience Research Unit, University of Vermont, Burlington, United States, noted that kids with ADHD take up smoking and become hooked at twice the rate of other adolescents. "If these findings are substantiated," Dr. Potter said, "these cognitive improvements may explain the high rates of smoking initiation and maintenance in ADHD."

Dr. Potter and colleagues carried out a double-blinded study of 8 teens ages 13 to 17 years, split equally as to gender. All had ADHD according to criteria from the Diagnostic and Statistical Manual of Mental Disorders, 4^th edition.

Nicotine was delivered by a skin patch. Comparison was to oral Ritalin and a placebo for both medications. The teens served as their own controls.

Reaction times significantly improved on 2 standard laboratory tasks that measure inhibition of responding no matter which drug was used. Tests included the Stroop Task, with nicotine significantly decreasing the so-called Stroop effect (P < .05). Nicotine worked better on this task than did Ritalin.

Another test that highlights the inability of kids with ADHD to inhibit behavior is the Stop Signal Task, with both drugs showing significant improvement compared to placebo (P < .01). Accuracy on this test did not change due to the drugs, nor did the reaction time, indicating the drugs worked by specifically changing inhibition and not motor performance per se.

Inability of children to inhibit behavior "is recognized as the core cognitive defect in ADHD," Dr. Potter said. In fact, the Stop Signal Task proves so difficult that many with ADHD never are able to reach the 50% inhibition criteria that need to be defined by the computer generating the signals. In essence, they fail the test.

The Stop Signal Task involves hitting a button when an X rather than an O is presented. Then a sound is presented after the letter, a quarter of the time, which is a signal not to press. Kids with ADHD have enormous trouble stopping themselves from hitting the button anyway. Nicotine reduced the stop signal deficit "almost to published norms" for the test, Dr. Potter said.

Co-investigator Paul Newhouse MD, department of psychiatry, University of Vermont, said, "It was a pretty surprising result that we got such a strong signal in such a small group [to show the nicotine effect in ADHD]."

Dr. Newhouse added that at least 3 pharmaceutical companies are working on novel nicotinic agents, and are "thinking of targeting ADHD" with these investigational drugs.

"We have a saying in the lab about nicotine [as a component of cigarettes]," Dr. Newhouse added. "'Good drug; bad delivery system.'"

Dr. Newhouse noted that long-term use of nicotine in a patch, by teens, has not been studied adequately to determine safety.


[Study Title: Acute nicotine administration improves behavioral inhibition in adolescents with attention-deficit/hyperactivity disorder (ADHD). Abstract 18.9]

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