AIDS and The Nervous System: A Focus On The AIDS Dementia Complex

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AIDS and The Nervous System: A Focus On The AIDS Dementia Complex

Infection by the human immunodeficiency virus (HIV), the biologic agent of the AIDS syndrome, has emerged as one of the most important threats to public health in the United States and its incidence is rapidly increasing. A highly lethal disease with over 70% of AIDS patients dying within 2 years of diagnosis. This disease has already become the leading cause of death in men aged 25-44 and women aged 25-34. The Centers for Disease Control have for the purpose of epidemiological surveillance, defined AIDS as a "reliably diagnosed disease that is at least moderately indicative of an underlying cellular immunodeficiency in a person who has no underlying cause of cellular immunodeficiency nor any other cause of reduced resistance reported to be associated with that disease." [5]

The pathophysiology of HIV is indicative of a retrovirus. At the cellular level the most distinct feature of AIDS is the depletion of the helper-inducer lymphocytes or T-helper cells. The specific antigen CD4 present on these lymphocytes appears to be the target of the AIDS retrovirus. HIV does not usually cause disease as soon as it is acquired and therefore in most cases, has a latency period which may be variable. The ultimate problem in this disease is the progressive immunosuppresslon due to the lack of lymphocytes.

The nervous system is an early and obvious site of disease in AIDS In addition to the opportunistic infections that the defect in cell mediated immunity allows, there is neurologic damage directly attributable to the AIDS virus. Dysfunction’s of practically all parts of the nervous system have been reported as a direct or indirect result of HIV infection [3]. The human immunodeficiency virus directly attacks cells in the nervous system, although it does not cause morphologic injuries to the neurons. It causes disabling, but not necessarily irreversible changes to the brain and spinal cord. The most common manifestation of this virus is a progressive dementia associated with subacute encephalopathy which is a part of the AIDS Dementia Complex. Spinal cord, cranial nerve, and peripheral nerve damage also occur but at a much lower frequency and are less likely to command the overall course or the disease. As more is learned about HIV infection, the effect on the nervous system becomes more apparent. Estimates on the Prevalence of neurologic consequences of AIDS range from 31-65% in adults and 50-90% in children[5].
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