Natural Hormone Showing Promise as Depression Treatment
> 12/18/2007 3:09:53 PM

There are many antidepressants with proven efficacy, but the very number and variety of these drugs points to the fact that none of them helps all the people all the time. Patients frequently have to suffer through multiple month-long trials to test out which drug will work for them. This is why the new type of medication heralded this month by Dr. Kamilla Miskowiak is of great interest.

Dr. Miskowiak set her sights on erythropoietin (EPO), the naturally produced hormone that regulates red blood cells. EPO has been used to treat anemia for a long time, but it was only in 2005 that Brines and Cerami discovered that it crosses the blood-brain barrier and has a noticeable effect on cognition. Dr. Miskowiak was intrigued by this discovery, but she recognized that it was not definite proof that EPO directly alters neural function.

In a double-blind experiment earlier this year, Dr. Miskowiak injected the experimental group with EPO and the control group with a simple saline solution. Patients given EPO had greater hippocampus activation up to a week later when encoding and identifying images. As the hippocampus's role in memory and learning makes it a prime focus of depression treatments, Dr. Miskowiak suggested in her paper that EPO could be a valuable new antidepressant. There were two possible holes in this hypothesis. One, EPO might merely be boosting neural activity by creating more blood cells and thus fueling the brain with more oxygen. Dr. Miskowiak ruled out this possibility by testing hemoglobin levels and administering amounts of EPO too low to affect red blood cell count. The second possible hole comes from the fact that this experiment did not actually find an improvement in performance, only in neural activation. If subjects could not really identify pictures any better, were they truly improving?

Dr. Miskowiak attempted to close that hole with a new study published this month in Biological Psychiatry. Using the same experimental setup with EPO and saline injections, she showed subjects faces displaying the gamut of human emotions. Experimental subjects showed dampened activation when viewing fearful faces but normal activation for every other emotion. This selective effect is promising because it shows that EPO can protect against the impact from negative stimuli without interfering with perception in general. The results also suggest that previous experiments may not have noticed a boost to task performance because EPO only affects the processing of specific stimuli. Future experiments should test whether EPO allows subjects to better control negative emotions in order to focus when performing potentially frightening or saddening tasks. Another fecund place for research might be the records of all of the millions of patients already treated for anemia. It is possible that the bonus neurological benefits of their medication will become apparent under closer scrutiny.

If EPO does indeed prove capable of regulating negative emotions, then it will be a valuable new tool in the fight against depression. Keep an eye out for FDA approval.

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