Researchers report that erythropoietin (EPO), better known as a performance-enhancing drug in sport, may improve cognitive functioning in patients suffering from bipolar disorder or depression. This raises hope for the first long-term treatment for this problem, which affects hundreds of millions of patients throughout the world, according to the investigators who presented their work at the European College of Neuropsychopharmacology conference in Vienna.
Medically, recombinant EPO is used for the treatment of anemia. The hormone, produced by the kidney, is essential for the production of red blood cells. EPO gives the blood a greater capacity to carry oxygen, and it is this characteristic which makes it attractive as a performance-enhancing drug (the cyclist Lance Armstrong admitted to using EPO).
While many people think of disorders such as bipolar disorder and depression as conditions that affect mood, they also affect cognitive function—how quickly and how well a brain functions. This slow-down in thinking can have serious effects on sufferers, making it more difficult to retain a job, pass an exam, or maintain a relationship.
Now a group of Danish scientists have discovered that EPO can help restore cognitive function in patients suffering from these mental disorders. These results are also described in an article “The Effect of Erythropoietin on Cognition in Affective Disorders—Associations with Baseline Deficits and Change in Subjective Cognitive Complaints” published in the August issue of European Neuropsychopharmacology. In two randomized controlled trials, the researchers assessed cognitive function in 79 patients suffering from depression or bipolar disorder. They assigned 40 of the patients to be given EPO for 9 weeks, with the remaining 39 being given a placebo. They found that EPO had beneficial effects on patients' completion of a range of cognitive tests, including tests on verbal memory, attention span, and planning ability. Tests showed that this improvement was maintained for at least 6 weeks after treatment finished (the longest follow-up time in the trials).
Kamilla Miskowiak, Ph.D., a researcher who leads the Neurocognition and Emotion in Affective Disorders Group based at the Psychiatric Centre Copenhagen, Copenhagen University Hospital, Rigshospitalet, said that “EPO treated-patients showed a five times greater cognitive improvement from their individual baseline levels compared with placebo treated patients. EPO-treated patients showed 11% improvement while placebo treated patients improved only by 2%. This effect of EPO on cognition was maintained 6 weeks after patients had completed their treatment.”
It was also found that patients who performed poorly in neuropsychological tests showed remarkably greater cognitive benefits when given EPO, according to Dr. Miskowiak, who noted that “we may be able to target patients for EPO treatment, and perhaps other future cognition treatments, based on how they do on neuropsychological tests.”
She pointed out that larger studies are needed to confirm that the effects that have been seen can be replicated, to confirm dosage, frequency of use, and so on.
“Although EPO is generally safe if patients' red blood cell levels are controlled regularly, there are certain groups for whom the risk of blot clots is too high,” she explained. “For example, people who smoke or who have previously had blood clots. So although these results hold out great promise, EPO treatment is not ready to be rolled out as a treatment just yet and may not be for everyone.”
The WHO estimates that around 350 million people suffer from depression, with a further 60 million suffering from bipolar disorder, but the drugs normally used to treat depression and bipolar disorders don't have any major effect on cognition. Up to 70% of patients in remission from bipolar disorder, and up to 40% in remission from depression continue to have cognitive problems. Currently there is no available effective treatment to target cognitive problems in these patients.