Does it affect NMDA? I thought it was nAChRs. The memantine, I mean.
Edited to add: you are correct. I found this possible explanation online.
"Memantine, a low-affinity, non-selective NMDAR antagonist, is indicated for treating Alzheimer's disease and used off-label to treat psychiatric illnesses.2 It seems paradoxical to consider this agent for treatment of schizophrenia, since its activity as an NMDA antagonist would appear to worsen psychotic symptoms. However, it appears to block NMDAR activity stimulated by low levels of glutamate, thereby perhaps protecting against neurotoxicity.2 Two small studies found it to be more effective than placebo in improving scores of positive, negative, and cognitive symptoms.7,8 However, a larger trial found no difference at endpoint in PANSS total scores, and an increase in adverse effects in the memantine group."