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February 1995

Plasma Cobalamin Levels Affect Information Processing Speed in a Longitudinal Study of HIV-1 Disease

Author Affiliations

From the Departments of Epidemiology and Public Health (Drs Shor-Posner and Baum), and Psychiatry (Drs Morgan, Wilkie, and Eisdorfer), University of Miami (Fla) School of Medicine.

Arch Neurol. 1995;52(2):195-198. doi:10.1001/archneur.1995.00540260101024

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

Design:  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.

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

Participants:  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.

Main Outcome Measures:  Biochemical measurement of plasma cobalamin; performance on information processing speed tasks.

Results:  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.

Conclusion:  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.