A complicated link between assailment and antidepressant drugs

Nearly half a 1000000 children in the U.Due south. have antidepressants. In 2007, the Centers for Disease Control and Prevention released a warning for fluoxetine, one of the well-nigh highly prescribed psychiatric medications. The drug's master chemical compound seemed to be causing a host of negative side effects in a subset of the young users.

"It's happening," said Rich Melloni, professor of psychology and director of the Program in Behavioral Neuroscience in the College of Science. "Kids are becoming irritated, aggressive, impulsive, agitated, hostile. So you lot ask the question: Why?" As behavioral neurobiologists, Melloni's team is using boyish animate being models to proceeds an agreement of why these negative side effects occur. Their findings are published in this month's issue of the journal Behavioral Neuroscience.

First, he and his research team administered regular doses of fluoxetine to healthy adolescent hamsters. The animals received either a low, moderate or high dosage, equivalent to what a human adolescent would receive to care for conditions such as feet, depression or obsessive-compulsive disorder, respectively.

They so observed the hamsters' behavior when presented with an intruder — or the mere odour of an intruder — in their muzzle. Hamsters that received the low dosage consistently demonstrated pregnant increases in ambitious behavior.

Adjacent the researchers looked at the hamsters' brains. They were surprised past what they found.

Melloni said that when a molecule called vasopressin is present at loftier levels in the brain, the assailment organization works in overdrive. Another molecule, serotonin, has the reverse affect.

"Think of serotonin as your brake for assailment and vasopressin equally your gas," said Melloni. If you want to go fast, he said, you lot tin can press on the gas, ease off the brake, or appoint in a combination of the 2. Fluoxetine, so to speak, is designed to push on the brake in social club to help people deal with the symptoms of depression. But the aggressive hamsters' brains had problems with both their gas pedals and their brakes.

Fluoxetine is a "serotonin reuptake inhibitor," meaning that it increases serotonin levels by preventing the molecule from being reabsorbed by the body. Lower serotonin has been linked to depressive symptoms in some patients.

But other neurological systems as well contribute to low, such as the molecules dopamine and norepinephrine. When these systems are dumb, patients tin can show similar symptoms every bit if they had an impaired serotonin organisation.

"Take that kid that presents with the same symptoms, but he has a dopamine or norepinephrine problem," said Melloni. "But when yous give him a serotonin drug, he may get aggressive, he may become worse."

Melloni'due south findings suggest that the children who experience the aggressive side furnishings of fluoxetine may non accept begun with an impaired serotonin system at all. "There's the likelihood," said Melloni, "that past virtue of the fact that our clinical diagnosis is non based in neurobiology, only rather in symptomology, that nosotros may exist giving kids a serotonin drug inappropriately."

The next step in the enquiry is to perform the same tests on hamsters with "ruined" serotonin systems. "Then allow's give these impaired hamsters [fluoxetine] and encounter if they become aggressive," Melloni said. "My judge is they are not going to exist."