A systematic review of the effects of novel psychoactive substances “legal highs” on people with severe mental illness

Introduction: Novel psychoactive substances (NPS) are synthetic substances that have been developed to produce altered states of consciousness and perceptions. People with severe mental illness (SMI) are more likely to use NPS than people without mental illness, but the short and long-term effects of NPS are largely unknown.
Method: We systematically reviewed the literature about the effects of NPS on people with SMI.
Results: We included 12 case reports, 1 cross-sectional survey and 1 qualitative study. Participants included mostly males aged between 20 and 35 years. A variety of NPS were used, including synthetic cathinones and herbs such as salvia. The most commonly reported effects of NPS were psychotic symptoms (in some cases novel in form and content to the patients’ usual symptoms) and significant changes in behaviour, including agitation, aggression and violence. Patients’ vital signs; blood pressure, pulse rate and temperature were also commonly affected.
Conclusion: NPS potentially have serious effects on people with severe mental illness but our findings have limited generalisability due to a reliance on case studies. There is a paucity of evidence about the long-term effects of these substances. Further research is required to provide a better understanding about how different NPS affect patients’ mental and physical health.
PROSPERO Identifier: CRD42015026944
Keywords: legal highs, novel psychoactive substances, psychotic disorders, severe mental illness, schizophrenia, systematic