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* This is the Professional Version. *

HIV-Associated Dementia

By Juebin Huang, MD, PhD

HIV-associated dementia is chronic cognitive deterioration due to brain infection by HIV.

Dementia is chronic, global, usually irreversible deterioration of cognition. 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.

Dementia should not be confused with delirium although cognition is disordered in both. The following helps distinguish them:

  • Dementia affects mainly memory, is typically caused by anatomic changes in the brain, has slower onset, and is generally irreversible.

  • Delirium affects mainly attention, is typically caused by acute illness or drug toxicity (sometimes life threatening), and is often reversible.

Other specific characteristics also help distinguish the 2 disorders (see Table: Differences Between Delirium and Dementia*).

Purely HIV-associated dementia is caused by neuronal damage by the HIV virus. However, in patients with HIV infection, dementia may result from other disorders, some of which may be treatable. These disorders include other infections, such as secondary infection with JC virus causing progressive multifocal leukoencephalopathy and CNS lymphoma. Other opportunistic infections (eg, cryptococcal meningitis, other fungal meningitis, some bacterial infections, TB meningitis, viral infections, toxoplasmosis) 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

Symptoms and signs may be similar to those of other dementias. Early manifestations include

  • Slowed thinking and expression

  • Difficulty concentrating

  • 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

  • Extensor-plantar responses

Mania or psychosis is sometimes present.

Diagnosis

  • Clinical evaluation

  • Measurement of CD4 count and HIV viral load

  • Prompt evaluation, including MRI and usually lumbar puncture, when deterioration is acute

HIV-associated dementia should be suspected in patients who have

  • Symptoms of dementia

  • Known HIV infection or symptoms or risk factors suggesting HIV infection

If patients known to have HIV infection have symptoms suggesting dementia, a general diagnosis of dementiais confirmed based on the usual criteria, including the following:

  • Cognitive or behavioral (neuropsychiatric) symptoms interfere with the ability to function at work or do usual daily activities.

  • These symptoms represent a decline from previous levels of functioning.

  • These symptoms are not explained by delirium or a major psychiatric disorder.

Evaluation of cognitive function involves taking a history from the patient and from someone who knows the patient plus doing a bedside mental status examination or , if bedside testing is inconclusive, formal neuropsychologic testing (see Assessment of cognitive function).

If patients with symptoms of dementia are not known to have HIV infection but have risk factors for HIV infection, they are tested for HIV.

In patients with HIV infection or suspected HIV-associated dementia, CD4 count and HIV viral load are measured. In patients with suspected or confirmed HIV and dementia, these values help determine how likely HIV-associated dementia (and CNS lymphoma and other HIV-associated CNS infections) is to be contributing to dementia. In patients who have HIV infection but not dementia, these values help determine how likely HIV-associated dementia is to develop.

If patients have dementia and HIV infection, other processes can cause or contribute to worsening dementia symptoms. Thus, the cause of cognitive decline, particularly sudden, severe decline—whether due to HIV or another infection—must be identified as soon as possible.

MRI, with and without contrast, should be done to identify other causes of dementia, and if MRI does not identify any contraindication to lumbar puncture, lumbar puncture should also be done.

Late-stage findings of HIV-associated dementia may include diffuse nonenhancing white matter hyperintensities, cerebral atrophy, and ventricular enlargement.

Prognosis

Patients with HIV infection and untreated dementia have a worse prognosis (average life expectancy of 6 mo) than those without dementia.

Treatment

  • Antiretroviral therapy

The primary treatment of HIV-associated dementia is antiretroviral therapy, which increases CD4+ counts and improves cognitive function.

Supportive measures are similar to those for other dementias. For example, the environment should be bright, cheerful, and familiar, and it should be designed to reinforce orientation (eg, placement of large clocks and calendars in the room). Measures to ensure patient safety (eg, signal monitoring systems for patients who wander) should be implemented.

Symptoms are treated as necessary.

* This is the Professional Version. *