"The serotonin system is just not doing its job," Dr. Ferris said.

"But it's amazing how little we really do know about the serotonin system."

Other neurological effects included a normalization of the brain's serotonin system, which can cause depression when it malfunctions.

It is likely the effect of partial agonistic action on the serotonin system.

But while the reuptake mechanism may respond quickly, the serotonin system can take weeks or months to readjust.

Anything, in fact, that relieves severe stress, which, he has found, is disruptive to the serotonin system.

Another example of a drug that interferes with the serotonin system is cocaine.

Dysregulation of the serotonin system, too, has been reported.

A substance is serotonergic if it produces its effects via interactions with the serotonin system.

Although scientists do not yet fully understand how the serotonin system works, higher circulating levels of it are associated with lighter moods.