NOS1AP and major depressive disorder: Cheah et al (2015) found an association between eight NOS 1 adapter protein (NOSAP1) polymorphisms and depression in a study of 235 schizophrenics in Australia. This protein has previously been strongly associated with schizophrenia, due to downregulation of NO. Lawford et al (2013) also investigated 13 NOS1AP SNPs in 121 Vietnam male war veterans with a diagnosis of PTSD.