Abnormal gamma oscillations, measured by electroencephalography (EEG), have been associated with chronic psychotic disorders, but their prevalence in the early phase of psychosis is less clear. We sought to address this by systematically reviewing the relevant literature. We searched for EEG studies of gamma band oscillations in subjects at high risk for psychosis and in patients with first episode psychosis. The following measures of gamma oscillations were extracted: resting power, evoked power, induced power, connectivity and peak frequency. Forty-five studies with a total of 3099 participants were included. There were potential sources of bias in the study designs and potential artefacts. Although there were few consistent findings, several studies reported decreased evoked or induced power in both high risk subjects and first episode patients. Studies using larger samples with serial EEG measurements, and designs that minimise artefacts that occur at the gamma frequency may advance work in this area.

通过脑电图（EEG）测得的伽马振荡异常已与慢性精神病性疾病相关，但在精神病早期阶段其患病率尚不清楚。我们试图通过系统地回顾相关文献来解决这个问题。我们在患有精神病的高风险受试者和患有首发性精神病的患者中搜索了有关伽马波带振荡的脑电图研究。提取了以下伽马振荡的度量：静止功率，诱发功率，感应功率，连通性和峰值频率。总共进行了45项研究，共有3099名参与者。研究设计和潜在伪像中可能存在偏见。尽管几乎没有一致的发现，但一些研究报告说，高风险受试者和首发患者的诱发或诱发能力降低。