Hyperactivity

...ba href=/hyperactivity/a/b disorder (ADHD) may be less likely to lead to abuse than the traditional immediate-release methylphenidate.

Dr.

Thomas J.

Spencer from Massachusetts General Hospital and Harvard Medical School in Boston and colleagues compared the abuse potential of immediate-release and controlled-release methylphenidate in 12 healthy adult volunteers.

None had been diagnosed with ADHD or any neurological or psychiatric disorder.

Using positron emission tomography (PET) scans, which measure dopamine transporter blockade, the investigators found that a 90-mg capsule of controlled-release methylphenidate produced the same dopamine blockade in the brain as a 40-mg capsule of immediate-release methylphenidate, although at a much slower rate.

Although the two formulations led to similar concentrations in the blood, controlled-release methylphenidate required a longer period of time to reach peak blood and brain levels and to block the dopamine transporter in the brain.

Unlike the immediate-release methylphenidate, the subjects reported no preference and detected no subjective effects with the controlled-release methylphenidate.

"The findings suggest that the abuse potential of oral methylphenidate is strongly influenced by the rate of delivery and not solely by the magnitude of plasma concentrations or brain transporter occupancy," the authors conclude.

"These results," they add, "advance understanding of the underlying central effects of methylph...

...ba href=/hyperactivity/a/b.

Children with CD4 counts below 660 cells per microliter, white blood cells used to follow the loss of immune function, were more likely to have conduct problems than were children with higher CD4 counts, the researchers note.

Children with higher IQ scores were less likely to have learning problems or behaviors associated with ADHD.

There were no gender differences for any of the behavioral parameters evaluated, the investigators observe, and there were no significant correlations between behavioral problems and neuroimaging results.

The source of behavioral abnormalities in HIV-positive children "is likely to be multifactorial, including factors such as prenatal drug exposure, difficult family environment, level of maternal education, changes in caregivers, exposure to lead, nutrition and poverty," the researchers suggest.

"As therapies improve and children live longer, studies such as ours will help raise awareness and promote the development of therapeutic interventions designed to improve learning and behavior in this population of children," the authors conclude.

SOURCE: Pediatrics, March 2006.

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...ba href=/hyperactivity/a/b disorder (ADHD) in children and teenagers, U.S.

health experts unanimously said on Thursday.

The Food and Drug Administration panel of outside advisers said company data on the stimulant drug, currently approved for sleep disorders, showed it worked for ADHD.

The FDA will make the final decision but usually follows the advice of its advisers.

© Reuters 2006.

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