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Acute severe isovolemic anemia impairs cognitive function and memory in humans
R B Weiskopf1, J H Kramer, M Viele
1Departments of Anesthesia, the Cardiovascular Research Institute, University of California, San Francisco, California 94143-0648, USA. weiskopf@jemo.ucsf.edu
Anesthesiology
|June 6, 2000
Summary
Acute anemia (low hemoglobin) significantly impairs cognitive function and memory, even at levels previously thought safe. These effects are reversible with erythrocyte transfusions, indicating a potential model for testing anemia treatments.
Area of Science:
- Hematology
- Neuroscience
- Anesthesiology
Background:
- Erythrocyte transfusions are vital for treating anemia and inadequate oxygen delivery.
- Previous research lacked sensitive measures to detect cognitive changes at low hemoglobin levels.
- This study investigated the impact of acute severe anemia on human cognitive function.
Purpose of the Study:
- To test the hypothesis that acute severe reductions in hemoglobin concentration alter human cognitive function.
- To identify specific cognitive domains affected by varying degrees of anemia.
- To assess the reversibility of cognitive deficits following erythrocyte transfusion.
Main Methods:
- Nine healthy volunteers underwent isovolemic reduction of hemoglobin to 7, 6, and 5 g/dl.
- Cognitive function was assessed using verbal memory and computerized neuropsychological tests.
- Control experiments were performed without hemoglobin alteration to account for experimental duration and time of day.
Main Results:
- Hemoglobin reduction to 7 g/dl showed no significant cognitive changes.
- Hemoglobin levels of 6 and 5 g/dl resulted in increased reaction times (horizontal addition, DSST) and impaired memory.
- Cognitive deficits were reversible upon return of hemoglobin to 7 g/dl via autologous erythrocyte transfusion.
Conclusions:
- Acute anemia to 7 g/dl does not detectably impair cognitive function.
- Hemoglobin levels of 6 and 5 g/dl cause subtle, reversible cognitive and memory impairments.
- This study provides the first prospective data on degraded cognitive function in acute anemia and establishes a model for testing anemia treatments.