In other MRS studies, there were no significant group differences reported with respect to Glx or Glu levels (cf., Cheng et al., 2018; Ende et al., 2013; Frischknecht et al., 2017; Zahr, Carr, et al., 2016; Zahr, Mayer, Rohlfing, Sullivan, & Pfefferbaum, 2014). GABA levels were unaffected by chronic alcoholism except in smokers (higher GABA at 1 week abstinence which resolved at 1 month) (Mason et al., 2006). With respect to Gln measured directly, it has been reported as higher (Thoma et al., 2011) and lower (Prisciandaro et al., 2016) in the anterior cingulate of AUD relative to control groups, while a yet another study observed no group differences but correlations in AUD between Gln levels in anterior cingulate and nucleus accumbens and craving (Bauer et al., 2013). In summary, additional in vivo research is required to determine the importance of glutamate to the dynamic course of AUD.
