People with schizophrenia are much more likely to smoke than the rest of the population and people suffering from depression and anxiety are also more likely to smoke as well. A study of 100 people with schizophrenia living in the North of England asked whether those who smoked had higher levels of anxiety and depression and whether suffering from anxiety and depression made the participants more likely to smoke. The researchers found that there was no significant difference 'in anxiety and depression scores as a function of smoking status' although men with schizophrenia were much more likely to smoke than women.
Martin, C.R. ... [et al] - Mood and smoking in schizophrenia Journal of Psychiatric and Mental Health Nursing November 2008, 15(9), 703-709