Serotonin hypothesis- individuals with OCD have reduced levels of serotonin, or deficiant serotonin metabolism. Drugs which increase serotonin levels have proved effective in the treatment of OCD. Drugs which affect other neurotransmitters are of little or no value in the treatment of OCD.
However, there are serious problems with the serotonin hypothesis. Drugs can be effective for many different reasons, and just because serotonin reduces the symptoms of OCD doesn't prove that low serotonin caused it in the first place.
Studies in which serotonin levels are assessed have found little…