In fact, enhanced expression of GNMT in cortical mixed neuron-glial cultures culture has been shown to be neuroprotective.139 In GNMT knockout mice, alterations in the adenosylmethionine pathway impair neurogenesis and contribute to cognitive decline.140 Mutations in genes encoding the glycine cleavage system also predispose mice and humans to neural tube defects.141. This evidence concerns the gene GNMT and Mental deterioration.