Is it true that people with low serotonin tend towards addiction?

We put this question to Professor Barry Everitt, Professor of Behavioural Neuroscience at Cambridge University

It's an interesting and good question. The answer is a difficult one to provide. What we do know is that individuals who are in withdrawal from drugs tend to have reduced levels of serotonin in key parts of the brain where the other transmitter I mentioned earlier, dopamine, is also important. There is a notion that one of the things that might cause you to take drugs again is an attempt to self-medicate, if you like, that lower level of serotonin in these key parts of the brain. That might be an interesting mechanism. Clearly serotonin is very closely linked to mood change and withdrawal induced mood change is a really quite difficult early problem for people trying to stay off drugs.