The importance of confounding factors in the evaluation of neuropsychological changes in patients infected with human immunodeficiency virus.

There are conflicting reports on the early effects of human immunodeficiency virus (HIV) infection on the nervous system. Some studies have suggested that there may be early cognitive impairment, while others have refuted this. We describe the results of extensive neuropsychological testing in a group of 40 infected subjects. These indicate that the degree of impairment is closely related to confounding factors other than the infection itself. Our conclusion is that the early stages of HIV disease are not associated with a high frequency of cognitive impairment if these confounding variables are taken into consideration.