Abnormalities in the mismatch negativity (MMN) component appear to be specific to schizophrenia. MMN is thought to indicate the occurrence of... Show moreAbnormalities in the mismatch negativity (MMN) component appear to be specific to schizophrenia. MMN is thought to indicate the occurrence of an automatic initial step in a cognitive process whereby the individual is alerted to changes in the auditory environment. In schizophrenia, a meta-analytic review has suggested that the MMN component is significantly reduced compared to controls. However, the findings related to the MMN component and early psychosis (EP) have been inconsistent. A literature search was conducted for data comparing persons experiencing EP and healthy controls. EP was operationalized as including persons putatively at risk (AR) for developing psychosis and those experiencing first episode psychoses (FEP). Fifteen studies were identified (N = 1076: EP = 628, Controls = 448) that met inclusion criteria. A fixed effect model was used to calculate the overall mean weighted effect size of the total sample (g = -0.380). A planned categorical moderator analysis included 37 effects sizes. A method of moments, random effects model was used to compare group means of categorical variables and assess between-group heterogeneity in reported effect sizes based on clinical group, MMN measurement type, and MMN deviant type. The MMN mean weighted effect sizes for the AR and FEP groups measured in amplitude in the duration deviant condition is g = -.251 and -.801, respectively. The difference in these means is statistically significant (QBetween = 17.77, df = 1, p < .0001). Diagnostic implications and the role of electroencephalography in cognitive rehabilitation are discussed. M.S. in Psychology, May 2014 Show less
