It occurs primarily in more advanced HIV infection when the CD4 cell counts are relatively low. While the progression of dysfunction is variable, it is regarded as a serious complication historically predicting death in less than one year.
Diagnosis is made by neurologists who carefully rule out alternative diagnoses.
No single test is available to confirm the diagnosis, but the constellation of history, laboratory findings, and examination reliably establish the diagnosis when performed by experienced clinicians. The cause of ADC is not fully known at present. Presence of the HIV virus is required, and there is good evidence that successful antiretroviral therapy, if started early enough, can induce a degree of improvement in neurologic performance. Evidence that antiviral therapy prevents ADC is incomplete and in some cases contradictory. However, most investigators recommend at a minimum that aggressive antiretroviral therapy with maximally CNS penetrating drugs be used when this diagnosis is likely.