you will chose the one that is most accessable, now won't you!
Serotonin is actually the chemical that interacts with the brain during the initial "attraction" phase of a relationship, along with dopamine and norepinephrine (it's no coincidence that the anti-depressants prescribed for OCD, serotonin-norepinephrine reuptake inhibitors, can cause a decrease in a person's ability to fall in love). Interestingly, lower-than-normal levels of serotonin are common among "newfound lovers" and are also common in, you guesssed it, people with OCD.
Consequently, you could say that the newly-lovestruck couple going to prom together for the first time have actually fallen into OCD with each other; although you'd probably receive strange looks from anyone who hears you utter such a bizzare bastardization of a ubiquitously understood phrase. Wow, the term "love-sickness" is starting to make a whole lot of sense now, isn't it?
Unlike Serotonin (which plays an important role in the early stage of a relationship), a chemical known as Oxytocin is linked to the long term bonding phase of a more mature romantic relationship. I bet you can guess what chemical is released into the brains of two lovers after they experience an orgasm (hint: it starts with a big O).
Oxytocin may not be directly linked to OCD, however. But Oxytocin and Sertonin, along with other neuro chemicals (such as Testosterone, Estrogen, Dopamine, Norepinephrine, and Vasopressin) interact to create the whole spectrum of "romantic love" that two humans experience together. An even larger variety of neurochemicals constantly work in parallel to create the full human emotional experience, which manifests itself mentally as well as physically (it's not just a coincidence that your palms start to sweat and your heart begins to beat a little faster when you run into that special someone).
Interestingly enough, due to the bizarre ways these neuro chemicals interact with your brain, certain levels of Oxytocin may play a role in OCD and Asperger's after all! Why else would the Journal of Neuropsychopharmacology publish a study2 in 2003 entitled Oxytocin Infusion Reduces Repetitive Behaviors in Adults with Autistic and Asperger's Disorders? This study argues that "repetitive behavior in autism spectrum disorders may be related to abnormalities in the oxytocin system, and may be partially ameliorated by synthetic oxytocin infusion." Say what?
Wait. Does this mean that having a lot of sex will decrease the amount of time you spend stimming and also cause you to spend less time focused on your special interests? I have no idea; I'm not a clinical neuropsychopharmacologist.
References
[1] "On Love," National Geographic, February 2006
[2] Neuropsychopharmacology (2003) 28, 193-198.
[3] Wikipedia contributors, "Love (scientific views)," Wikipedia, The Free Encyclopedia, http://en.wikipedia.org/w/index.php?tit ... =113411348 (accessed March 11, 2007).