Stimulant medications such as Ritalin have been prescribed for decades to treat attention deficit hyperactivity disorder (ADHD), and their popularity as "cognition enhancers" has recently surged among the healthy, as well. What's now starting to catch up is knowledge of what these drugs actually do in the brain. In a paper publishing online in Biological Psychiatry, University of Wisconsin-Madison psychology researchers David Devilbiss and Craig Berridge report that Ritalin fine-tunes the functioning of neurons in the prefrontal cortex (PFC)—a brain region involved in attention, decision-making and impulse control—while having few effects outside it.

Because of the potential for addiction and abuse, controversy has swirled for years around the use of stimulants to treat ADHD, especially in children. By helping pinpoint Ritalin's action in the brain, the study should give drug developers a better road map to follow as they search for safer alternatives.

At the same time, the results support the idea that today's ADHD drugs may be safer than people think, says Berridge. Mounting behavioral and neurochemical evidence suggests that clinically relevant doses of Ritalin primarily target the PFC, without affecting brain centers linked to over-arousal and addiction. In other words, Ritalin at low doses doesn't appear to act like a stimulant at all.

"It's the higher doses of these drugs that are normally associated with their effects as stimulants, those that increase locomotor activity, impair cognition and target neurotransmitters all over the brain," says Berridge. "These lower doses are diametrically opposed to that. Instead, they help the PFC better do what it's supposed to do."

Release date: June 24, 2008
Source: University of Wisconsin, Madison