Plasma cobalamin levels affect information processing speed in a longitudinal study of HIV-1 disease

To determine whether information processing speed is influenced by change in plasma cobalamin status in human immunodeficiency virus type 1 disease.

A longitudinal study, using autoregression, to evaluate the relationship between plasma cobalamin status and change in information processing speed assessed by Posner Letter Matching, Sternberg Short-Term Memory Search, Figure Visual Scanning and Discrimination of Pictures, and continuous paired associates learning tasks.

University of Miami (Fla) School of Medicine from fall 1987 through summer 1991.

Eighty-four human immunodeficiency virus type 1-infected homosexual men aged 20 to 55 years. None of the subjects displayed acquired immunodeficiency syndrome-defining symptoms at baseline; over the course of the study, 9.5% progressed to acquired immunodeficiency syndrome.

Biochemical measurement of plasma cobalamin; performance on information processing speed tasks.

Significant improvement in the Posner Letter Matching NI-PI (Name Identity minus Physical Identity) differential was associated with becoming cobalamin adequate or remaining adequate. Becoming cobalamin deficient, in contrast, was associated with a significant decline in the speed of accessing overlearned name codes.

Normalization of plasma cobalamin inadequacy in human immunodeficiency virus type 1 disease may provide significant improvement in the speed of retrieving overlearned information from long-term memory.