Of the glutamate receptors, the NMDA type has received the most research attention in relation to AD (Gass and Olive 2008). Consistent with that literature, a recent survey of 10 glutamate system genes showed a moderate association of AD (i.e., an odds ratio of 2.18) with markers in GRIN2A, which encodes NR2A, the N-methyl-D-aspartate receptor subunit 2A (Schumann et al. 2008). The effect was initially demonstrated in one sample and replicated in an independent sample. That study did not, however, examine any of the genes encoding kainate receptor subunits. Kainate receptors are important modulators of interneuron excitability in the hippocampus. Carta et al. (2003) showed that ethanol potently inhibits this effect at plasma concentrations associated with the ingestion of 1-2 alcoholic drinks, an effect that appeared to be specific for kainate receptors and physiologically relevant. The authors argued that the effect may partially explain some of the paradoxical excitatory actions of alcohol, which are perceived as positive by some individuals and could contribute to the development of alcoholism. The only other kainate receptor gene that has been studied as a
