Violent offences of methamphetamine users and dilemmas of forensic psychiatric assessment

Methamphetamine (MA), an extremely addictive synthetic stimulant, has quickly spread to become the most frequently used illicit drug in China. People with a history of chronic and heavy MA use have a high possibility of exhibiting schizophrenia-like psychotic symptoms, mainly delusions of reference, auditory hallucinations and cognitive deficits. These emerging findings suggest MA use increases aggression and violence and that there is a correlation between MA use and violence. However, it is unclear how to assess the capacity of criminal responsibility in “MA-induced” psychosis and how to set clear boundaries between schizophrenia and MA-induced psychosis when only limited and inconsistent evidence is available. Furthermore, a final persuasive differential diagnostic method based on improved understanding of schizophrenia and MA-induced psychotic disorders has yet to be developed. This paper will evaluate the epidemiology, social harm, and forensic psychiatric assessment of MA users, propose a future direction for the differential diagnosis between MA-induced psychotic disorders and schizophrenia, and put forward some practical solutions to assess the capacity of criminal responsibility of defendants with drug-induced psychotic disorder.