RNA is similar to DNA, but its job is to synthesize proteins. The last decade or so has led to the discovery of the microRNA, which is small and does not synthesize protein. Researchers have since clamored to discover what exactly microRNA does do, and it has been recently found that microRNA play a critical role in the brain.
In a recent research review, it was shown that microRNA respond to brain injury so that certain types of microRNA were increased, and others were decreased. The implication of this discovery is that a blood test to determine the levels of different microRNA may be an effective biomarker for diagnosing brain injury. This could be important, especially in instances where there is no external injury to the head and the traditional CT scan shows no damage-as is often the case in mild traumatic brain injury or diffuse axonal injury.
Saugstad JA. MicroRNAs as effectors of brain function with roles in ischemia and injury, neuroprotection and neurodegeneration. Journal of Cerebral Blood Flow & Metabolism. (September 2010).