Frontal Glutamate and ?-Aminobutyric Acid Levels and Their Associations With Mismatch Negativity and Digit Sequencing Task Performance in Schizophrenia.

ABSTRACT: Auditory mismatch negativity (MMN) is a biomarker for schizophrenia thought to reflect glutamatergic N-methyl-d-aspartate receptor function and excitatory-inhibitory neurotransmission balance. However, the association of glutamate level with MMN has not been directly examined in patients with schizophrenia, to our knowledge.To investigate the contributions of glutamate and ?-aminobutyric acid (GABA) to MMN and digit sequencing task (DST) performance, an assessment of verbal working memory, in schizophrenia.Fifty-three control participants from the community and 45 persons with schizophrenia from outpatient clinics completed an electroencephalographic session for MMN, magnetic resonance spectroscopy for glutamate and GABA, and a DST. The study dates were July 2011 to May 2014, and the dates of our analysis were May 2014 to August 2015.Glutamate, GABA, the ratio of glutamine to glutamate, MMN amplitude, and DST. Structural equation modeling was used to test the effects of neurochemistry and MMN amplitude on DST performance.The 45 persons with schizophrenia were a mean (SD) of 37.7 (12.8) years and the control participants were 37.1 (13.1) years. The schizophrenia group had a mean (SD) of 14.7 (12.1) years of illness. Mismatch negativity amplitude (F?=?4.39, P?=?.04) and glutamate (F?=?9.69, P?=?.002) were reduced in the schizophrenia group. Smaller MMN amplitude was significantly associated with lower GABA level (P?=?.008), lower glutamate level (P?=?.05), and higher ratio of glutamine to glutamate (P?=?.003). Reduced MMN amplitude was linked to poor verbal working memory in schizophrenia (P?=?.002). Modeling revealed that a proxy of glutamatergic function, indexed by the ratio of glutamine to glutamate, influenced a path from the ratio of glutamine to glutamate to MMN to verbal working memory (P?=?.38 [root-mean-square error of approximation, P?

SUBMITTER: Rowland LM 

PROVIDER: S-EPMC4740214 | biostudies-literature | 2016 Feb

REPOSITORIES: biostudies-literature