Odor sensitivity is impaired in HIV-positive cognitively impaired patients

An estimated 7-28% of patients infected by the human immunodeficiency virus (HIV) develop dementia and at least 50% develop mild neurocognitive impairment. Past studies have shown odor identification impairments in HIV + neurocognitively impaired patients. It is difficult, however, based on an odor identification test to state with certainty that individuals with cognitive impairment have sensory olfactory deficits, because odor identification tests are known to draw upon cognitive skills. In the present study odor detection sensitivity was evaluated using an ascending, forced-choice, two-alternative, odor threshold test for butanol. Subjects were divided into three groups, HIV seropositive (HIV+) neurocognitively impaired, HIV+ neurocognitively unimpaired, and HIV negative, based on neurological and psychological testing. An analysis of variance revealed significantly poorer odor sensitivity for the HIV+ neurocognitively impaired group than for the two control groups. A significant negative correlation between degree of cognitive impairment and olfactory sensitivity was also found. We suspect that the olfactory deficits found in the HIV+ neurocognitively impaired subjects are primarily due to damage to the central nervous system; however, nasal infection may be a contributing etiology.