HIVAssociated Cognitive Impairment Adults

Over the past two decades, various terms have been used to describe the cognitive features, including mental slowness, diminished concentration, and a decline in memory in the setting of HIV infection. These cognitive changes are variably associated with changes in behavior (lethargy, apathy, and diminished emotional responses) and motor symptoms (clumsiness, gait abnormalities, tremor, and reduced motor control). The term HIV-associated dementia or HIV dementia incorporates the cognitive changes seen in HIV-1 infection as well as those occurring in the setting of AIDS, previously termed "AIDS dementia complex" ( complex was used to indicate the added presence of central nervous system--based motor deficits, often myelopathy and behavioral changes, including psychosis). As such, the term HIV dementia is considered to be synonymous with AIDS dementia complex, HIV encephalopathy, and HIV-associated dementia complex. A separate term, HIV- associated minor cognitive/motor disorder, has been used to denote minor degrees of cognitive and motor impairment that are not sufficient for the diagnosis of dementia. According to the American Academy of Neurology AIDS Task Force, y this term is appropriate because it is unclear whether this degree of impairment uniformly progresses to overt dementia. The term HIV-associated delirium should be used in the setting of an alteration in consciousness with a rapid worsening of cognitive function in at least two domains. With these terms, three general categories can be used to classify HIV-associated cognitive dysfunction ( .Table.44-7 ). The terms HIV encephalitis, HIV-associated diffuse poliodystrophy, and HIV leukoencephalopathy are pathological findings that may be seen at autopsy in patients with HIV dementia and should not be used to denote clinical syndromes.

Pathogenesis and Pathophysiology. Much has been learned about the biology of HIV-1, the cells it infects, and the mechanisms by which viral entry into cells occurs. However, just how HIV-1 exerts its effects on the central nervous system remains uncertain and continues to be the focus of ongoing research. Gross examination of the HIV- infected individuals' brain who had cognitive impairment shows cerebral atrophy of variable degrees. There is ventricular


TABLE 44-7 -


Category 1 (HIV-associated, minor)

0.5 SD below normal on standardized neuropsychological tests

Decline in work or other activities of daily living (ADLs)

Symptoms for 1 month

Criteria for HIV-l-associated dementia or delinum is absent

No other etiology

Category 2 (HIV-associated dementia)

Marked impairment in at least two ability domains

Significant impairment in work and other ADLs

Symptoms for 1 month

No other etiology

Free of delirium for a period sufficient to establish the presence of dementia

Category 3 (HIV-associated delinum)

Clouding of consciousness

Marked, rapid worsening of cognitive function in

2 domains

SD = Standard deviation.

enlargement, particularly in the frontal and temporal lobes, widening of sulci, and attenuation of deep cerebral white matter with, at times, softening of the centrum semiovale.76i , y A spectrum of characteristic gross and microscopic changes has been described and categorized by an international working group consensus in 1991 as follows (.Table.44-8 ). HIV-1 encephalitis is characterized by foci of inflammatory cells, microglia, macrophages, and multinucleated giant cells (Fig. 44-6 (Figure Not Available) ). Location tends to be perivascular with predominance in the basal ganglia and subcortical white matter, although to a lesser degree the cortical gray matter may also be affected in some cases. In adult series, HIV encephalitis is reported in up to 90 percent (15 to 90 percent) of AIDS cases studied. Although HIV encephalitis is one of the most impressive postmortem findings, the degree of severity appears to be greater in adults than infants and young children. y1 HIV-1 leukoencephalopathy is characterized by diffuse myelin pallor. There is diffuse damage to white matter with myelin loss. Associated findings such as reactive astrogliosis, the presence of macrophages, and multinucleated giant cells may also be present. Symmetrical white matter pallor can be


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