range from marginal to severe (Valcour et al., 2004; Vance and Struzick, 2007). Cognitive dysfunction can have a major impact on a patient’s ability to maintain activities of daily living, remain employed, or engage in other regular activities such as driving.
Common comorbidities among HIV-infected populations with and without neurocognitive disorder include psychiatric and behavioral disorders, which can lead to functional impairment and potential disability. Within psychiatric disorders, major depression, delirium, and anxiety are seen in 25 to 50 percent of individuals living with HIV infection (Pence et al., 2006). Studies have suggested the risky behaviors associated with bipolar disorder or schizophrenia may lead to higher prevalence rates of HIV infection among affected populations. These disorders are somewhat less common than major depression, but if untreated may lead to impairment and disability (Vlassova et al., 2009). Behavioral disorders include untreated drug dependence, which can lead to impairment and disability. Injection drug use can lead to immune suppression and increased HIV transmission (Fama et al., 2009; Vlassova et al., 2009). Cocaine, amphetamine, and alcohol abuse can also lead to increased immune suppression (Fama et al., 2009), decreased adherence, and poor virologic outcomes (Vlassova et al., 2009). Psychological reactions to negative life experiences can lead to posttraumatic stress disorder, seen in 13 to 20 percent of individuals living with HIV infection. Posttraumatic stress disorder cooccurs with major depression and substance use disorders in 25 to 50 percent of individuals living with HIV infection and is associated with lower CD4 counts and incompletely suppressed viral load (Vranceanu et al., 2008).
A growing number of older adults are affected by HIV/AIDS, including those who have aged with the disease due to advances in treatment as well as individuals who have been infected later in life. In 2007, the largest number of new infections occurred among those ages 40 to 44. Furthermore, according to CDC estimates for 2007, 28 percent of HIV-infected adults were over age 45. New aspects of chronic HIV infection will likely become apparent as the HIV/AIDS population ages.
Older age is associated with more rapid progression of HIV infection. Research has linked age as an independent prognostic factor for patients with HIV (Egger et al., 2002). Patients older than age 50 who began combination antiretroviral therapy showed higher clinical progression of disease, including higher rates of mortality, compared to younger patients beginning treatment (Kirk and Goetz, 2009). Furthermore, untreated older adults progress to AIDS and death much faster than younger individuals. In addition, older adults may experience longer-term effects from the virus,