NPY and bipolar disorder: Multiple studies have observed expression deficits in NPY and NPY mRNA in the PFC from post-mortem tissue of subjects with schizophrenia and subjects with bipolar disorder (Gabriel et al., 1996; Kuromitsu et al., 2001; Hashimoto et al., 2008a), although it is important to note that Caberlotto and Hurd (1999) found decreased NPY mRNA only in post mortem tissue of subjects with a clinical diagnosis of bipolar disorder, and not those with schizophrenia or other disorders.