Adam W Carrico Michael H Antoni Lawrence Young and Jack M Gorman

Because of the many the stressors inherent in HIV infection, psychosocial and biomedical issues must be addressed for successful disease management (Schnei-derman et al., 1994). The anticipation and impact of HIV antibody test notification; emergence of the first symptoms of disease; changes in vocational plans, lifestyle behaviors, and interpersonal relationships; and the burdens of complex medication regimens are all highly stressful. These multiple challenges can create a state of chronic stress that may overwhelm an individual's coping resources and significantly impair emotional adjustment to ongoing demands of the illness (Leserman et al., 2000). Accordingly, HIV-positive individuals are at increased risk for developing an affective or adjustment disorder across the disease spectrum (Bing et al., 2001). Although reductions in mood disturbance have been observed following the introduction of highly active anti-retroviral therapy (HAART; Rabkin et al., 2000), the risk of developing major depressive disorder is two times higher in HIV-positive samples when compared to HIV-negative peers (Ciesla and Roberts, 2001; see also Chapters 4 and 9 in this volume).

With substantial reductions in morbidity and mortality following the advent of HAART, clinical care of HIV-positive persons has improved dramatically such that the disease is now commonly conceptualized as a chronic illness (CDC, 1997;Mannheimeretal., 2005). However, not all HIV-positive patients treated with HAART display adequate viral suppression because of the difficulties some patients have adhering to treatment and the emergence of drug-resistant strains of the virus (Bangsbergetal., 2001;Tamalet etal., 2003). Questions also remain regarding the appropriate time to initiate HAART in HIV-positive patients. Variability in the extent of immune reconstitution, an increased incidence of opportunistic infections in the months following initiation, and profound drug-related toxicities have all been reported (Ledergerber et al., 1999; Lederman and Valdez, 2000; Volberding, 2003; Yeni et al., 2004). These issues perpetuate the great uncertainty that surrounds this chronic, albeit unpredictable, disease.

Because HIV-positive persons endure a chronic disease that requires adaptation across a variety of domains, individual differences in the ways they adapt to these challenges may affect not only quality of life but also disease processes. Research in psychoneuro-immunology (PNI) has examined the potential bio-behavioral mechanisms whereby psychosocial factors such as stressors, stress responses, coping, and negative affective states influence disease progression (Antoni, 2003a). Psychosocial factors are thought to relate to immune-system function in humans via stress- or distress-induced changes in hormonal regulatory systems (Kiecolt-Glaser et al., 2002). Several adrenal hormones, including cortisol and catecholamines (norepinephrine and epinephrine), are altered as a function of an individual's appraisals of and coping responses to stressors (McEwen, 1998). What is particularly relevant to HIV/AIDS research is the observation that a variety of neuroendocrine abnormalities occur in both clinically depressed (Gillespie and Nemeroff, 2005) and HIV-positive (Kawa and Thompson, 1996) populations. In HIV-positive persons, elevations in these hormones have also been associated with alterations in multiple indices of immune status (Antoni and Schneiderman, 1998). The most definitive PNI work has illuminated such biobehavioral mechanisms through longitudinal and intervention designs where changes in psychosocial factors are mapped onto changes in immunologic indicators and clinical disease progression over time in different HIV-positive populations. In this chapter, we review seminal research findings that support the relevance of PNI pathways in HIV disease progression. Although the majority of PNI investigations with HIV-positive persons were conducted prior to the availability of HAART, more recent findings indicate that enhanced psychological adjustment may facilitate virologic control and bolster immunocompetence, enhancing the effectiveness of HAART.

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