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HIV-associated dementia is chronic cognitive deterioration due to brain infection by HIV.
HIV-associated dementia (AIDS dementia complex) may occur in the late stages of HIV infection. Unlike almost all other forms of dementia, it tends to occur in younger people. Purely HIV-associated dementia is caused by neuronal damage by the HIV virus. However, in patients with HIV infection, dementia may result from other infections, such as secondary infection with JC virus causing progressive multifocal leukoencephalopathy. Other opportunistic infections (eg, fungal, bacterial, viral, protozoan) may also contribute.
In purely HIV-associated dementia, subcortical pathologic changes result when infected macrophages or microglial cells infiltrate into the deep gray matter (ie, basal ganglia, thalamus) and white matter.
Prevalence of dementia in late-stage HIV infection ranges from 7 to 27%, but 30 to 40% may have milder forms. Incidence is inversely proportional to CD4+ count.
Symptoms and signs may be similar to those of other dementias (see Dementia : Symptoms and Signs). Early manifestations include slowed thinking and expression, difficulty concentrating, and apathy; insight is preserved, and manifestations of depression are few. Motor movements are slowed; ataxia and weakness may be evident. Abnormal neurologic signs may include paraparesis, lower-extremity spasticity, ataxia, and extensor-plantar responses. Mania or psychosis is sometimes present.
Generally, diagnosis of dementia in patients with HIV infection is similar to that of other dementias (see Dementia : Diagnosis). However, when patients present with an acute change in cognitive function, the cause must be identified as soon as possible.
CT or MRI should be done to check for signs of CNS infection (eg, toxoplasmosis). MRI is more useful than CT because it can exclude other CNS causes of dementia (eg, progressive multifocal leukoencephalopathy, cerebral lymphoma). Late-stage findings of HIV dementia may include diffuse nonenhancing white matter hyperintensities, cerebral atrophy, and ventricular enlargement. If no contraindication is identified by neuroimaging, lumbar puncture see Lumbar puncture (spinal tap) is done to rule out infection.
The primary treatment is highly active antiretroviral therapy, which increases CD4+ counts and improves cognitive function (see Human Immunodeficiency Virus (HIV) Infection : Treatment). Supportive measures are similar to those for other dementias (see Dementia : Treatment).
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