Brain iron-deficiency causes reduced learning capacity in rats.

Rats made nutritionally iron-deficient (ID) showed a significant deficit in water-maze learning compared with normal rats. The deficit was substantially greater the longer the rats stayed on the ID diet. The deficit in learning was established prior to any significant decrease in hemoglobin (Hb) level in the blood. Three weeks after the ID rats were placed on a control diet, the Hb level was restored to normal value, but the cognitive deficit remained. Previous studies showed that the behavioral effects of ID are mediated by a decrease in the functional activity of the dopaminergic system. The ID effects on learning and memory may be related to the irreversible diminished dopaminergic neurotransmission that results from ID.