Attention Deficit Discovery
Nov. 6, 2000 -- What's behind conditions such as attention deficit hyperactivity disorder (ADHD) and schizophrenia -- conditions that affect the ability to learn, pay attention, and remember? The brain chemical serotonin may be a key, according to a study presented at a neuroscience meeting in New Orleans.
"Both schizophrenia and ADHD are marked by disordered thinking and problems in learning, memory, and attention," lead author William Wetsel, PhD, tells WebMD. "We were interested in using an animal model to understand these processes, and perhaps design more effective drugs to treat these disorders." Wetsel is associate professor of psychiatry and behavioral sciences at Duke University School of Medicine in Durham, N.C.
For this research, the mice were genetically altered to have abnormal levels of chemicals in their brains and exhibit problems with learning and attention. When these mice were tested with standard tasks, the antidepressant drug Prozac, which increases serotonin levels, did improve their ability to learn. A lack of serotonin is thought to affect mood, behavior, memory, learning, appetite, and sleep. "When we gave these animals [Prozac], which affects the serotonin system, it had a dramatic effect on learning and memory, improving performance fourfold." Wetsel says.
Nancy Mueller, MD, says, "The only way to find a chemical basis for the way drugs work is by using animal models. The more we learn about ADHD, the more we realize it's a neurological phenomenon, not just a behavioral disorder." Mueller, who was not involved in the study, is a neurologist in private practice in Englewood Cliffs, N.J.
This study suggests that Prozac, and possibly other medications that work the same way, hold promise as a treatment for ADHD. Wetsel notes that treatments for people with ADHD have begun to include the use of Prozac, "by and large with good success."
Mueller says that she sees many who already are being treated with such drugs are seeing positive results. This animal research helps explain why this class of drugs -- known as selective serotonin reuptake inhibitors -- might be beneficial for ADHD, she says.
However, Lawrence Greenhill, MD, says he doesn't know of any solid evidence confirming that Prozac is useful in ADHD. He thinks ADHD children who are treated with these drugs are being treated for other disorders, such as major depression or obsessive-compulsive disorder. Greenhill is professor of clinical psychiatry at Columbia University College of Physicians and Surgeons in New York City.
At this point, we aren't ready to make the leap to new treatments, Wetsel says. "We have here some basic research information that may be useful in future therapies, but we're not quite there yet." He believes this research eventually may lead to more effective treatment strategies for ADHD, schizophrenia, and other conditions such as Tourette syndrome.