No abstract

The most severe HAND diagnosis (HAD) was rare, but milder forms of impairment remained common, even among those receiving CART who had minimal comorbidities. Future studies should clarify whether early disease events (e.g., profound CD4 decline) may trigger chronic CNS changes, and whether early CART prevents or reverses these changes.

Combination antiretroviral therapy (CART) has greatly reduced medical morbidity and mortality with HIV infection, but high rates of HIV-associated neurocognitive disorders (HAND) continue to be reported. Because large HIV-infected (HIV+) and uninfected (HIV−) groups have not been studied with similar methods in the pre-CART and CART eras, it is unclear whether CART has changed the prevalence, nature, and clinical correlates of HAND. We used comparable methods of subject screening and assessments to classify neurocognitive impairment (NCI) in large groups of HIV + and HIV − participants from the pre-CART era (1988–1995; N = 857) and CART era (2000–2007; N = 937). Impairment rate increased with successive disease stages (CDC stages A, B, and C) in both eras: 25%, 42%, and 52% in pre-CART era and 36%, 40%, and 45% in CART era. In the medically asymptomatic stage (CDC-A), NCI was significantly more common in the CART era. Low nadir CD4 predicted NCI in both eras, whereas degree of current immunosuppression, estimated duration of infection, and viral suppression in CSF (on treatment) were related to impairment only pre-CART. Pattern of NCI also differed: pre-CART had more impairment in motor skills, cognitive speed, and verbal fluency, whereas CART era involved more memory (learning) and executive function impairment. High rates of mild NCI persist at all stages of HIV infection, despite improved viral suppression and immune reconstitution with CART. The consistent association of NCI with nadir CD4 across eras suggests that earlier treatment to prevent severe immunosuppression may also help prevent HAND. Clinical trials targeting HAND prevention should specifically examine timing of ART initiation.

In the past two decades, several advancements have improved the care of HIV-infected individuals. Most importantly, the development and deployment of combination antiretroviral therapy (CART) has resulted in a dramatic decline in the rate of deaths from AIDS, so that people living with HIV today have nearly normal life expectancies if treated with CART. The term HIV-associated neurocognitive disorder (HAND) has been used to describe the spectrum of neurocognitive dysfunction associated with HIV infection. HIV can enter the CNS during early stages of infection, and persistent CNS HIV infection and inflammation probably contribute to the development of HAND. The brain can subsequently serve as a sanctuary for ongoing HIV replication, even when systemic viral suppression has been achieved. HAND can remain in patients treated with CART, and its effects on survival, quality of life and everyday functioning make it an important unresolved issue. In this Review, we describe the epidemiology of HAND, the evolving concepts of its neuropathogenesis, novel insights from animal models, and new approaches to treatment. We also discuss how inflammation is sustained in chronic HIV infection. Moreover, we suggest that adjunctive therapies -treatments targeting CNS inflammation and other metabolic processes, including glutamate homeostasis, lipid and energy metabolism -are needed to reverse or improve HAND-related neurological dysfunction. Competing interests statementThe authors declare no competing interests. HHS Public AccessAuthor manuscript Nat Rev Neurol. Author manuscript; available in PMC 2016 July 08. Author Manuscript Author ManuscriptAuthor ManuscriptAuthor Manuscript chronic infection that can be managed, is associated with a near-normal lifespan and in which opportunistic infections are rare 1 .The first major advancement was an understanding of the direct relationship between HIV replication and subsequent immunological and clinical progression. This finding emphasized the need to completely suppress HIV replication in order to control disease progression.The second major advancement was the development and deployment of combination antiretroviral therapy (CART), which can provide effective systemic suppression of HIV replication. The introduction of CART in the mid-1990s resulted in a 50% decline in the rate of death from AIDS, substantial decreases in rates of maternal-infant transmission, reduced incidence of opportunistic infections, and a 40-50% decrease in the incidence of HIVassociated dementia (HAD), which was previously common and is the most severe form of cognitive impairment associated with the infection 2 .The third major change in the care of HIV+ patients was the ability to monitor the efficacy of CART through the reliable and widespread measurement of CD4 + helper T cells, plasma HIV RNA levels and antiretroviral resistance profiles, all of which are now fully integrated into routine clinical care in the developed world and used to optimize treatment for individual patients. Plasma viral l...