HIV dementia: an evolving disease

Cross talk between growth factors and viral and cellular factors alters neuronal signaling pathways: implication for HIV-associated dementia

HIV-associated dementia (HAD) is a serious neurological disorder affecting about 7% of people with AIDS. In the brain, HIV-1 infects a restricted number of cell types, being primarily present in macrophages and microglial cells, less abundant in astrocytes, and rarely seen in oligodendrocytes and neurons. Lack of a productive HIV-1 infection of neuronal cells suggests the presence of an indirect pathway by which the virus may determine the brain pathology and neuronal dysfunction seen in AIDS patients. Among the participants in this event, viral proteins including gp120 and Tat, along with host factors including cytokines, chemokines, and several signaling pathways have received considerable attention. In this article, we discuss the most recent concepts pertaining to the mechanisms of HIV-1-induced neuronal dysfunction by highlighting the interplay between signal transduction pathways activated by viral and host factors and their consequences in neuronal cell function.

Viral diseases of the central nervous system

Viral diseases of the central nervous system encompass a wide range of different processes, mainly inflammation affecting the brain (encephalitis), the meninges (meningitis), or a combined meningoencephalitis. The spinal cord can be affected as well (myelitis). Another group of viral-related disorders, sometimes without a clear pathophysiological mechanism disclosed, include post-viral illnesses. All of these groups of diseases are discussed in this article, with an emphasis on their imaging presentation, using magnetic resonance imaging.