Semantic clustering inefficiency in HIV-associated dementia.

Although HIV is detectable throughout the CNS, its preferential disruption of fronto-basal ganglia systems is thought to underlie the neurobehavioral syndrome of HIV-associated dementia. Semantic clustering, a measure of organizational strategy during learning and retrieval, is commonly impaired in patients with frontal systems dysfunction, but has not previously been evaluated in HIV-associated dementia. The current study examined semantic and serial clustering strategies on a list-learning task in 15 individuals with HIV-associated dementia, 44 HIV-infected individuals without dementia, and 24 healthy comparison subjects. Results indicated a stepwise decline in the use of semantic, but not serial, clustering with increasing severity of HIV-associated cognitive disorder. Findings suggest that HIV-associated dementia is associated with inefficient use of higher-level encoding and retrieval strategies, perhaps mediated by a disruption of fronto-basal ganglia systems.