Stimulant drugs can cause persistent changes in the brain. Imaging studies show that these changes are most apparent in dopamine transporter (DAT) or receptor availability within the striatum.

This work focuses on influences of stimulant use on dopaminergic function assessed using nuclear-medicine imaging (PET/SPECT). Included are 39 studies on 655 cocaine, amphetamine, methamphetamine or nicotine users, as well as 690 healthy controls. Metaanalyses were conducted separately for D2/D3 receptors and dopamine transporters of the entire striatum, its subregions caudate and putamen respectively.

Meta-analyses results regarding nicotine did not show significant effects between smokers and nonsmokers. In cocaine users there was a significant decrease in dopamine receptor availability in all regions. The striatal DAT availability was significantly increased in cocaine users. Methamphetamine users showed a significantly decreased dopamine receptor and transporter density in all regions. Significant results also indicate a lower transporter availability in all regions. Amphetamine users showed reduced DAT availability in the striatum, as well as in the sub regions.

This meta-analysis provides evidence that there are ongoing changes in the dopaminergic system associated with the use of stimulants. Especially the results of cocaine, methamphetamine and amphetamine use mainly showed a downregulation. In addition, this meta-analysis is the first to include nicotine. This subset of studies showed evidence for a decreased receptor and DAT availability but no significant results were found in the metaanalyses.

Epidemiological studies suggest schizophrenia and substance misuse to be associated with a higher rate of violence and crime.

The literature was evaluated to assess whether people with schizophrenia who use substances have an increased risk for violence and disturbed behaviour.

A detailed Medline analysis was performed and relevant studies were reviewed.

A large number of studies have linked substance misuse in schizophrenia with male gender, high incidence of homelessness, more pronounced psychotic symptoms, non-adherence with medication, poor prognosis, violence and aggression. The latter has been proved by clinical, epidemiological and longitudinal prospective studies of unselected birth cohorts. The increased risk for aggression and violent acts cannot be interpreted only as a result of poor social integration. Male gender, more severe psychopathology, a primary antisocial personality, repeated intoxications and non-adherence with treatment are important confounding variables.

Substance misuse has been shown consistently to be a significant risk factor for violence and disturbed behaviour. Future research should try to evaluate possible pharmacological and psychosocial treatment approaches.