Memantine effects on auditory discrimination and training in schizophrenia patients

The uncompetitive low-affinity NMDA receptor antagonist, memantine, acutely increases electrophysiological measures of auditory information processing in both healthy subjects (HS) and patients with schizophrenia. Memantine effects on functional measures of auditory discrimination performance and learning are not known; conceivably, beneficial effects on these measures might suggest a role for memantine in augmenting the cognitive and functional impact of auditory targeted cognitive training (TCT). Here, carefully characterized HS (n = 20) and schizophrenia patients (n = 22) were tested in measures of auditory discrimination performance (words-in-noise (WIN), quick speech-in-noise (QuickSIN), gaps-in-noise) and auditory frequency modulation learning (a component of TCT) on 2 days about a week apart, after ingesting either placebo or 20 mg memantine po, in a double-blind, within-subject cross-over random order design. Memantine modestly enhanced functional measures of auditory discrimination in both schizophrenia patients (WIN) and HS (WIN and QuickSIN), as well as auditory frequency modulation learning in schizophrenia patients. These findings converge with a growing literature showing that memantine can enhance a range of metrics of auditory function. These properties could contribute to the apparent benefits of memantine as an adjunctive treatment in schizophrenia, and suggest that memantine might augment learning and potentially clinical gains from auditory-based TCT.