Wednesday, September 7, 2011

Neuroaids- A Disease of Memory Loss in HIV+ Patient

HIV/AIDS (human immunodeficiency virus/acquired immune deficiency syndrome) is primarily an immune system disorder but it also has an effect on the nervous system and may lead to a number of severe neurological disorders. NeuroAIDS, the novel neurologic disorders, are prime consequence of damage to the peripheral and central nervous system by HIV. The clinical syndromes of Neuroaids include myelopathy, sensory neuropathy, cognitive/motor disorder, brain infections, HIV dementia, and disorders of the muscle and spinal cord. In spite of potent antiretroviral therapy, many people who have HIV, experience amnesia (Memory Loss) and other cognitive problems.

The BBB in HIV-associated NeuroAIDS
Neuroaids- A Disease of Memory Loss in HIV+ Patient
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Any part of the nervous system such as spinal cord, the brain, nerves, or muscle can be affected by HIV. Depending on involved part, symptoms of Neuroaids in infected individuals may vary from memory loss, dizziness, headache, numbness, weakness, vision changes, pain or trouble walking. Neurologic disorders such as primary central nervous system lymphoma (PCNSL) and opportunistic infections may occur only in patients with AIDS at advanced stage. While neurologic conditions like HIV-associated dementia and HIV-associated neuropathy may occur even in patients with AIDS at well-controlled HIV stage.

Other nervous system obstacles that occur as a result of the drugs used to treat disease or disease itself include pain, shingles, seizures, lack of coordination, spinal cord problems, anxiety disorder, difficult or painful swallowing, fever, depression, vision loss, destruction of brain tissue, gait disorders, and coma.  These symptoms may become mild to severe progressively with the increasing stages of AIDS.

Antiretroviral treatment slows the development of HIV disease by suppressing HIV replication in 40-60 % of HIV-infected people. Even after Antiretroviral treatment, mild-to-moderate neurological deficits may develop in some cases and full-blown dementia may develop up to 5 percent patient. These all complications are communally known as NeuroAIDS. Until now, researchers were not able to explain this medical mystery. But researchers of Albert Einstein College of Medicine of Yeshiva University have solved this longstanding medical secrecy. 29th June issue of The Journal of Neuroscience published their findings.

As founded by Einstein researchers in a previous study, HIV infects about 5 % of brain cells known as astrocytes. Astrocytes bolster a network of blood vessels called the blood-brain barrier (BBB) which prevents voyage of harmful substances from the bloodstream into the brain. Even a minute level of astrocyte infection can deeply damage the BBB, as shown by the researchers. Toxic signals have been emitted by few infected astrocytes through specialized channels which may kill neighboring uninfected astrocytes. This may lead to weakening of the BBB and after that allow the harmful complexes to enter the brain, as said by Joan Berman, Ph.D., professor of pathology and of microbiology & immunology at Einstein. A laboratory model of the BBB which is constructed from human cells and an examination of HIV infected brain tissue of macaque monkeys give the evidence of this mechanism. So the drugs which have capacity to reduce cascade of damaging signals triggered by infected astrocytes might help in treating or preventing NeuroAIDS.


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