Monoamine oxidase (MAO) B messenger RNA (mRNA) levels in the striatum correlated with central nervous system viral loads. A, MAO B mRNA level, as measured by Nanostring analysis, positively correlated with viral load in the basal ganglia (BG, P = .030). B, MAO B mRNA level also positively correlated with viral load in the cerebrospinal fluid (CSF; P = .001). Viral loads were expressed as simian immunodeficiency virus (SIV) copy equivalents per microgram of RNA (A) or per milliliter of CSF (B). Statistical analyses used Spearman correlation.