Almost half of combination antiretroviral therapy (cART)-treated HIV patients experience some degree of neurocognitive impairment (neuroHIV). To search for underlying pathology, scientists analyzed the brains of monkeys infected with simian immunodeficiency virus (SIV) then treated with cART. The majority of the SIV-infected macaque brains showed signs of unusual lymphocyte-dominant inflammation, suggesting that persistent neuroinflammation may underlie cognitive problems in cART-treated HIV patients.