MMP9 and schizophrenia: Thus, increased activity of the MMP9 system was associated with higher levels of prefrontal function in experimental animals models [4, 5], also with neuropsychiatric illnesses such as schizophrenia or multiple sclerosis [16, 17] and The results obtained in males with bipolar illness on the WCST and in healthy males on the Stroop test may suggest that under certain conditions, a correlation of higher levels of neuropsychological function with C allele (connected with lower transcriptional activity for the MMP9 gene) may exist.