Central Nervous System Damage

Central Nervous System Damage

Although monocytes and macrophages can be infected by HIV, they appear to be relatively resistant to being killed by the virus. These cells, however, travel throughout the body and carry HIV to various organs, including the brain, which may serve as a hiding place or "reservoir" for the virus that may be relatively resistant to most anti-HIV drugs.

Neurologic manifestations of HIV disease are seen in up to 50 percent of HIV-infected people, to varying degrees of severity. People infected with HIV often experience

• Cognitive symptoms, including impaired short-term memory, reduced concentration, and mental slowing
• Motor symptoms such as fine motor clumsiness or slowness, tremor, and leg weakness
• Behavioral symptoms including apathy, social withdrawal, irritability, depression, and personality change

More serious neurologic manifestations in HIV disease typically occur in patients with high viral loads, generally when a person has advanced HIV disease or AIDS.

Neurologic manifestations of HIV disease are the subject of many research projects. Current evidence suggests that although nerve cells do not become infected with HIV, supportive cells within the brain, such as astrocytes and microglia (as well as monocyte/macrophages that have migrated to the brain) can be infected with the virus. Researchers postulate that infection of these cells can cause a disruption of normal neurologic functions by altering cytokine levels, by delivering aberrant signals, and by causing the release of toxic products in the brain. The use of anti-HIV drugs frequently reduces the severity of neurologic symptoms, but in many cases does not, for reasons that are unclear. The impact of long-term therapy and long-term HIV disease on neurologic function is also unknown and under intensive study.