Patients suffering from bipolar disorder or depression may have their cognitive function improved if they take a hormone known as erythropoietin (EPO), a recent study showed.

Currently, no treatments targeting cognitive problems in patients suffering from these disorders are available, according to the European College of Neuropsychopharmacology.

The hormone is mainly produced by the kidney and allows the blood to hold more oxygen, reported Science Daily. This quality makes EPO a desirable performance-enhancing drug for athletes, Champion cyclist Lance Armstrong was stripped of his seven Tour de France titles after he admitted using EPO to increase his stamina and improve recovery time.

Bipolar disorder and depression affect both mood and cognitive function. These disorders can cause difficulty in concentrating, irritability, and loss of interest, according to Delta Medical Center.

In the experiment, consisting of 79 patients suffering either from bipolar disorder or depression, 39 patients were treated with EPO and 40 patients with a placebo for nine weeks. Patients who were given EPO had improved cognitive function.

“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 percent improvement while placebo treated patients improved only by two percent,” study leader Dr. Kamilla Miskowiak told Science Daily.

Cognitive improvement from patients treated with EPO was maintained for a minimum of six weeks after the treatment was finished, the longest follow-up period in the trials, Miskowiak told Science Daily.

To confirm the results and the proper dosage, Miskowiak says bigger studies need to be conducted, although the hormone is already being used for medical purposes. When patients’ red blood cell levels can be regularly controlled, EPO is generally safe.

However, certain groups such as smokers or those with previous blood clots have too high a risk for blood clots to be treated with EPO.

The study may mark the beginnings for the first long-term treatment of these disorders.

Read More: 6 Different Types Of Depression, From Bipolar Disorder To Seasonal Affective Disorder