People with unipolar depression and bipolar disorder may experience cognitive difficulties, even when they’re not currently depressed. In a study published in the journal European Neuropsychopharmacology in 2016, researchers led by Caroline Vintergaard Ott determined that treatment with the hormone erythropoietin (EPO) may help. EPO is produced in the kidney and increases the production of hemoglobin and red cells.
Seventy-nine participants with unipolar or bipolar disorder were randomized to receive infusions of either EPO or a saline solution once a week for eight weeks. By the end of the study, those who received EPO showed significant improvements in the speed of their complex cognitive processing compared to those who received saline. EPO is known to induce the production of red blood cells. The improvements in processing speed lasted for at least another six weeks after red blood cell production would have normalized.
Those participants who received EPO not only had improved scores on tests of processing speed, they also reported fewer cognitive complaints. The EPO treatment was most likely to be effective in participants who had more impaired cognition at the beginning of the study.
In previous research by the same research group presented by Kamilla W. Miskowiak at the 2014 meeting of the International Society of Bipolar Disorders, EPO also improved sustained attention and recognition of happy faces.