From the American Psychiatric Association
Not Just a Childhood Disease

TORONTO, Canada—Treatment with mixed amphetamine salts extended release (XR) (Adderall XR) improves information processing speed and accuracy in adults with attention-deficit/hyperactivity disorder (ADHD), according to findings presented at the annual meeting of the American Psychiatric Association.

Once thought to be primarily a disorder of childhood, ADHD is now known to frequently extend into adolescence and adulthood. Analysis of the National Comorbidity Replication Survey revealed that 3% of a nationally representative sample of 10,000 US adults satisfied diagnostic criteria for ADHD, and that more than one third of those diagnosed with ADHD had not been diagnosed until adulthood.

In a recent study, 15 adults aged 19 to 25 with ADHD were randomized to receive mixed amphetamine salts XR or placebo for 3 weeks and were then crossed over to the other group for another 3 weeks. The treatment group received 20 mg mixed amphetamine salts XR daily in the first week, 40 mg/day in the second week, and 50 mg/day in the third week.

The primary outcome measures were changes in the speed and accuracy of information processing during neurocognitive testing using the computer-assisted CogScreen-Aeromedical Edition test, which measures working memory, information processing speed, mental flexibility, and other parameters.

At study week 3, accuracy scores on a visual—spatial working memory test were higher in the treatment group than the placebo group (95% vs 93%; P = .027). At week 6, the scores in the group switched from placebo to active treatment improved, and scores in the group switched from treatment to placebo remained unchanged.

Improvements in the accuracy of information processing with mixed amphetamine salts XR were paralleled by improvements in response speed. In patients who received placebo first, response speed improved after switching to active treatment, while those who received mixed amphetamine salts XR first maintained their improved response speed, even after switching to placebo.

“One unexpected finding was that patients who received mixed amphetamine salts XR in the first treatment period and who were then switched to placebo for the second treatment period either maintained or improved their accuracy and response speed despite no longer receiving the medication,” said Gary Kay, PhD, of the Washington Neuropsychological Institute, Washington, DC. “This finding suggests some lasting effects of psychostimulant treatment on certain aspects of neurocognitive processing in young adults with ADHD.”

At a follow-up of 30 days following the last dose of mixed amphetamine salts XR, no serious adverse events were reported.