The discovery of a correlation between hormone levels, concussion and recovery may be the first step in establishing a blood test for safe "return-to-play" for athletes.
A preliminary observation from a research study has demonstrated that results from a blood test could gauge the degree of affect or injury and the timeliness for recovery in athletes who have recently experienced a concussion.
For athletes who have sustained a concussion, results from the blood test may lend an objective and independent assessment to better inform decisions regarding the presence of an injury, and, perhaps, whether the injury has resolved enough to resume athletic participation. At present, concussion evaluation protocols that determine the appropriateness for safe return-to-play are largely based on clinical observation, and, in some instances, have been criticized as being "too subjective."
Professor Michael La Fountaine, Director of The Institute for Advanced Study of Rehabilitation and Sports Science in the School of Health and Medical Sciences at Seton Hall University, is lead author of the study, "Suppression of Serum Prolactin Levels after Sports Concussion with Prompt Resolution Upon Independent Clinical Assessment to Permit Return-to-Play."
The paper, to be published in an upcoming edition of the Journal of Neurotrauma, found a relationship between concussion injury and decreased levels of serum prolactin (or "PRL"), a hormone produced by the pituitary gland that can be monitored through a simple blood test.
In addition to the decreased levels of serum prolactin detected following a concussion, the research notably found that serum prolactin levels rose during the two weeks following the concussion, and this rise mirrored the independent clinical observation - as per current protocol - of a resolution of concussion symptoms and a resumption of sports participation.
"These findings are preliminary, but nonetheless promising," said La Fountaine, an Associate Professor in the Department of Physical Therapy who holds accreditation as a Certified Athletic Trainer (ATC). "This is only the first step in establishing a relationship between concussion and evidence from a blood test, but it's a potentially important one. The decreased serum prolactin levels early after injury and their subsequent rise over the two week study observation period demonstrates a return to normal; the changes to serum prolactin that we observed appear to be a secondary consequence to the injury. This is important because prolactin is released from the pituitary gland in response to changes in dopamine activity in the brain. Dopamine is an important messenger in the brain and plays a role in regulating pituitary function, motor control, and the limbic system, which is associated with emotions, motivation and long-term memory, to only name a few.
"In addition to being what could be a first step in the process of developing a blood test to identify and track the timeliness for recovery in athletes after concussion," he continued, "these preliminary findings are interesting because they provide us with insight to a potential consequence of concussion that wasn't previously described and might help explain some of the symptoms that we see clinically after injury. Naturally, there are a number of new questions and the need for more work to be done."
To determine the effect of concussion on serum prolactin concentrations, blood was drawn from male college athletes within 48 hours of concussion and again at 7 and 14 days post-injury.
The study found:
- At the initial post-concussion test, serum prolactin concentrations were reduced between roughly 50-500% compared to the 14 day post-injury test, when the concussion injury symptoms had resolved.
- After the initial post-concussion reading, each athlete demonstrated rising serum prolactin concentrations at each successive visit.
- In all athletes tested, serum prolactin concentrations increased from the lower quartiles in samples obtained closer to the time of injury to higher quartiles at 14 days post-injury.
- The rise in serum prolactin concentrations accompanied the resolution of symptoms and the independent clinical decision to permit a return-to-play.
- At the initial post-concussion test, the athlete with the lowest level of serum prolactin (Q1: 2.4 ng/mL) complained of sexual dysfunction and loss of libido, symptoms consistent with coincident hypogonadism, which also resolved as serum prolactin concentrations increased and symptoms of concussive injury abated by the last test at 14 days following concussion.
- At the initial post-concussion test, the athlete with the highest level of serum prolactin (Q3: 9.0 ng/mL) was symptom-free within 2 days of concussion and cleared to resume athletic participation.
- The remaining athletes followed a typical resolution of somatic and cognitive symptoms and were cleared for participation by the second (7 days) and third (14 days) exams, respectively.
- Although the decision to permit a return-to-play was made by independently and according to clinical observation protocol - without the benefit of knowing about the increase in serum prolactin levels - no athlete was cleared to return-to-play until after their serum prolactin concentration entered the fourth quartile from their recorded low mark at initial post-concussion testing.
Professor LaFountaine concluded, "The links between serum prolactin levels with concussion and recovery could be significant. Whether considering the degree of impact or degree of symptom resolution, the blood test results mirrored the concurrent clinical protocol to evaluate the injury. Now, we need to fine tune our future work to support the current findings and replicate the study on a much larger body of athletes, preferably in a case controlled setting with pre-injury evaluation data. In addition, considering the underlying relationship we've begun to investigate, studies of serum growth hormone and other pituitary hormones could yield additional insights with clinical implications."
The article, accepted for publication by the Journal of Neurotrauma, may be found here; a media report on these findings for "24/7 Health," syndicated to more than 1000 radio stations as part of the iHeart Radio network, can be found here and here.