Hi, I am researching about obssessive compulsive disorder and its relation to the neurotranmitter serotonin.I know that patients with OCD showed...

I can tell you from personal experience, and numerous
discussions with my doctor, that OCD is not caused by too much serotonin, but that
SSRI's can, in milder cases, help alleviate some of the anxiety that leads to obsessive
compulsive behaviors.  The trick becomes distinguishing between the different symptoms
and/or what medications work for each individual.  I know people who take SSRI's for
depression, anxiety, obsessive compulsive behaviors, and attention-deficit/hyperactivity
disorders.  I also know people, particularly my middle school students, usually boys,
who take other types of medications for the attention deficit/hyperactivity issues. 
While the causes of these chemical imbalances appear to be as varied as the individuals
who report them, my doctor has told me that SSRI's in particular, and
anti-depressants have not been shown to cause levels of these brain chemicals to
increase.