PET scans show us that, in sexual addiction, the surge of dopamine and its subsequent recession captures the brain, which then wants another hit. The surge of dopamine is the pleasure pay-off but, actually, it is in the subsequent depletion that irritability, restlessness, discontent, depression, anxiety and all the negative stuff lurks. So we want to get back on the train and repeat whatever it was that gave us the best bang for our buck. Why do some people pick alcohol, whilst others choose drugs or sex? Well, we are researching that now

Wouldn't this make addicts want to take medication to deal with this problem?

There are five dopamine receptors - D1 to D5. The D2 receptor is the addiction receptor. The other four have nothing to do with addiction. Dopamine receptors are also involved in Parkinsonism and some major mental illnesses, such as schizophrenia. However, all the medications that we've used for Parkinsonism, dopamine deficiency or mental illnesses, just don't work for addiction. We don't have a drug that successfully increases dopamine, other than Thorazine, Stelazine or Haldol, and they don't act on the D2 addiction receptor. The Parkinsonian drugs that increase dopamine don't act on the addiction receptor either.

A dopamine increasing silver bullet for addicts is being sought but it does not exist today. I don't think they'll find it because there are too many different genes and chromosomes involved.

There are many minor players in the user’s brain chemistry but this is the major player in all compulsivities. Should we conclude that we are all deficient in dopamine? With alcoholism and drugs the answer is yes. It's either a down-regulated system, which means it's not functioning properly, or it's an actual depletion of dopamine. We drink, drug and have sex because it increases our dopamine.