Concerns are growing from increasing prevalence rates for comorbid substance misuse and mental illness. Along with understanding which clinical populations are at high risk, an epidemiologically informed approach is needed to assess effectiveness of established service delivery. The aims of the study is to investigate the risk of developing an alcohol and other psychoactive substances dependence syndrome according to area of residence.

A cross-sectional survey design was used analysing data from the Psychiatric and Addictive Dual Disorders in Italy Study. Staff rating was used to assess comorbid substance use.

Significant differences were found between different geographical areas (Northern vs. Centre vs. Southern Italy). Peculiar diagnostic subgroups showed higher risk to develop such comorbid condition, whilst a number of clinical and sociodemographic variables, including area of residence, were associated with the risk to develop a dependence syndrome.

High comorbid rates do not seem necessarily the direct result of biological features inherent in schizophrenia, but social factors play an important role. A number of risk factors associated with dual diagnosis could build up an evidence base about how many people with dual diagnosis present and what the nature of their substance use is, providing targeted service planning and policy making. The higher risk of developing a dependence syndrome as associated with area of residence, could be considered as a reliable proxy measure of effective integration between mental health and addiction services. There is the need for implementing appropriate shared programmes to fill this gap in targeted areas.