Published online Aug 19, 2020. doi: 10.5498/wjp.v10.i8.187
Peer-review started: March 20, 2020
First decision: April 26, 2020
Revised: June 25, 2020
Accepted: July 19, 2020
Article in press: July 19, 2020
Published online: August 19, 2020
Schizophrenia spectrum disorders impact functioning, reduce quality of life and increase the risk of physical illness and premature mortality. Nutritional intervention studies aimed at decreasing body weight have demonstrated efficacy in improving metabolic outcomes; however, few studies have explored the impact of interventions designed to modify diet on mental health outcomes.
To synthesize the existing experimental studies of adjunctive diet modification as an intervention in the treatment of psychotic disorders, analyze findings related to effectiveness and safety, highlight knowledge gaps and limitations, and set forward recommendations for future research studies.
An extensive a priori search strategy was developed and the databases Embase, Embase Classic, Ovid MEDLINE were searched. Screening and data extraction were completed in duplicate. Studies included in this analysis were experimental studies of an adjunctive dietary intervention (overall dietary pattern or education on dietary change) for treatment of schizophrenia spectrum disorders. No restrictions were placed on control groups or blinding. The studies were required to report a mental health outcome.
Twenty-five clinical trials were identified, along with two additional protocols and two meta-analyses. Nineteen of the clinical trials reported improvement in one or more mental health domain including psychosis symptoms, cognition, and quality of life. A high level of heterogeneity was found with respect to patient population, intervention, and study design. All of the studies included lifestyle or psychosocial components in addition to dietary modification. The nutrition advice provided to participants was poorly described overall and compliance was not assessed. The studies that showed benefit tended to have a smaller sample size and were less likely to be randomized but were more likely to use a group delivery intervention.
Further research assessing effectiveness and efficacy of clearly reported dietary interventions is warranted, especially those using rigorous methodology, modifying diet in isolation and assessing participant compliance.
Core tip: While guidelines exist related to the role of nutrition interventions in the management of obesity and physical comorbidities in patient with schizophrenia spectrum disorders, there is limited clinical use in the management of mental health symptoms. This systematic review identified and analysed the findings of 25 clinical trials which modified participant diet and measured a mental health outcome. Nineteen reported improvement in one or more domain; however, many used additional interventions in combination with nutrition, and failed to report a detailed intervention protocol or assess compliance, limiting the conclusions that can be drawn. Further research is warranted using rigorous methodology.