For the original trial, the researchers recruited patients with detectable virus (HIV-1 RNA levels greater 400 copies/mL) who had not received any prior antiretroviral therapy. The researchers gave all patients 2 antiviral drugs (zidovudine and lamivudine). They also randomly assigned patients to receive one of 3 additional therapies (efavirenz alone, abacavir alone, or abacavir and efavirenz together). To ensure that the researchers and the patients would know who received which treatment, they gave dummy pills (placebos) to patients assigned to efavirenz or abacavir. In this substudy, the researchers compared neuropsychological symptoms and test results of patients assigned to receive efavirenz with those of patients assigned to receive abacavir and placebo. The tests measured cognition, thinking ability, sleep experience, anxiety, and depression. They were given to patients 1, 4, 12, and 24 weeks after starting therapy.