The human body creates an analgesic called endogenous morphine, or endorphins, that are released in response to intense stimuli such as exercise, excitement, pain, and orgasm. These painkillers are endogenous opioid peptides originating in the pituitary gland, brain, and spinal cord that function as neurotransmitters, blocking pain and creating a sense of well being upon release. They are partially behind “runner’s high”, which occurs after continuous, strenuous exercise. Released endorphins allow a runner to surpass what would otherwise be their physical limits, as well as creating a sense of euphoria and happiness (a similar euphoria one experiences when ingesting opiates). Generally speaking, the feelings endorphins cause exist to tell us that we are doing a good thing – like eating food and having sex – and to encourage us to keeping seeking those things out.
It is the chemical’s analgesic properties, however, that are of particular interest to scientists at Michigan University led by Alexander DaSilva, who have successfully used a technique called transcranial direct current stimulation, or tDCS, to catalyze the release of endorphins. In this procedure, a tiny amount of current (2 milliamps) is applied to the brain, altering the behavior its component neurons. Previously, a similar procedure has been used to alter the speed of neuronal reactions and neuroplasticity – making a person able to react and learn faster. The Defense Advanced Research Projects Agency has used this process to “speed up the training of military snipers”.
In this case, tDCS caused the release of endogenous m-opioids (a type of endorphin) when electrodes were placed over the motor cortex. In the researchers’ study, the pain thresholds of test subjects increased significantly, though certain types of pain – such the kind caused by migraines – were not mediated. The scientists think that with repeated use, tDCS could address migraine pain as well.
If further study reveals this method of releasing natural painkillers to treat chronic pain to be viable, doctors could “decrease the use of opiates in general, and consequently avoid their side effects, including addiction”, says DaSilva. At the moment, the researcher caution that more analysis is necessary before tDCS can be used as treatment for chronic pain. In other words, don’t go out and buy a tDCS kit for that backache.