1. Cerebral blood flow and metabolism were measured in 16 patients with pernicious anemia. Seven of the patients were restudied in various stages of therapy.
2. The patients fell into two equal groups, those with severe anemia and those with moderate or no anemia. In the first group, cerebral blood flow was increased and cerebral vascular resistance decreased; in the second group, cerebal blood flow was decreased and vascular resistance increased. In both groups, cerebral oxygen and glucose consumption was decreased, as was cerebral venous oxygen tension .
3. There was a good correlation between the mental status defects and cerebral oxygen consumption and between severity of neurologic involvement and cerebral oxygen consumption. There was no correlation between cerebro-vascular resistance and cerebral oxygen consumption, nor between degree of anemia and cerebral oxygen consumption.
4. Specific therapy resulted in a moderate increase in cerebral oxygen consumption and cerebro-vascular resistance. In no instance did cerebral oxygen consumption become normal.
5. The disparity between the functional ability of the patients and the low values for cerebral metabolism is discussed.
6. It is concluded that pernicious anemia results in specific nervous system involvement not related to the anemia, and that this damage is at least partially irreversible in many patients.