Exclusion criteria included recent (past year) pregnancy, seizures, mental retardation, dementia, neurosurgery, and a history of head injury with loss of consciousness for greater than 10 min. In addition, participants were required to have no acute illness, an IQ score greater than 70, and no major neurological or medical (i.e., chronic obstructive pulmonary disease, Type 1 or Type 2 diabetes, cirrhosis, hepatic encephalopathy, ocular disorders, etc.) disorders unrelated to HIV-1. Positive urine toxicology or breathalyzer tests or recent (past year) dependence upon alcohol, cocaine, or opiates were also exclusions. However, current use of methadone was not. Subjects were likewise excluded if they met the DSM-IV criterion for a diagnosis of schizophrenia or bipolar disorder. Major depressive disorder was not an exclusion.
