Substance Use Disorders (SUDs) are perhaps the most confounding, debilitating diseases we are facing. The personal, familial, public, social and economic suffering caused by SUDs is immeasurable. SUDs are now the leading causes of morbidity and mortality worldwide. Yet despite substantial advances in our understanding of the etiology and pathophysiology, therapeutic options are both limited and largely ineffective. Diana, et al, report on mechanisms and evidence that support the uses and further study of rTMS as new modalities in addiction treatment.
The dorsolateral prefrontal cortex (DLPFC) is an area in the prefrontal cortex of the brains of humans and primates. It is thought to be one of the most recently evolved parts of the human brain. It is unique because it undergoes a prolonged period of maturation that lasts until adulthood. The DLPFC is not an anatomical structure per se, as most imagine, but rather a functional aspect, which provides a new and novel target for innovative treatments that impact the human reward system.
What Is rTMS?
TMS, simply stated, is a high frequency electromagnet. It is thought to interrupt or enhance neural signals. It has been successfully used in treatment for resistant depression for over five years. Recent high-quality imaging studies have shown that high‐frequency rTMS, when targeting the DLPFC, results in a sustained increase of dopamine (DA) levels in the human ventral striatal complex. The challenge of increasing dopamine in this area of the brain has confounded neuroscientists for decades.
The mechanism of action of rTMS involves neuromodulation of subcortical areas, such as the NAc and the VTA, via its broader action on cortical areas such as DLPFC.
Recently, two sham‐controlled and double‐blind controlled studies supported the idea that deep rTMS results in a substantial reduction in number of drinks per day in patients with alcoholism, as well as the number of cigarette smoked per day in addicted smokers.
Why Does This Matter?
As experts at NIH and NIDA are calling for research and breakthrough treatments for SUDs, rTMS has been suggested to help with cravings for drugs, drug withdrawal and drug withdrawal-related sleep and depression symptoms. The long-term neurophysiological changes induced by rTMS have the potential to affect behaviors relating to drug taking, craving and relapse. In addition, rTMS is currently undergoing trials in pain management.
Finding non-pharmacological, less invasive treatments of addictive disease and chronic pain is the holy grail of neuroscience and addiction medicine. Only more time and investment in high-quality research will provide the answers we seek.
Diana M., et al. Rehabilitating the addicted brain with transcranial magnetic stimulation. Nat Rev Neuroscience. 2017 Nov;18(11):685-693. doi: 10.1038/nrn.2017.113. Epub 2017 Sep 29.