Drug addiction is a chronic disease that affects more than 5 percent of the world’s population. Over 64,000 people are thought to have died in the U.S. from a drug overdose in 2016 and according to recent estimates, over 21 million Americans aged 12 and above are living with a substance abuse disorder.
We know that the brain’s reward-processing circuits are thrown off balance when addicted, as the brain receives excessive amounts of dopamine. Dopamine plays a critical role in reward-mediated motivation and learning, as well as in experiencing pleasure. When the brain gets too much dopamine, it continues to search for that “high” in favor of “lesser” pleasures normally derived from other daily rewards, such as eating a chocolate bar or getting recognition at work.
This is why we call addiction a brain disease, but despite this, until recently, researchers had not come up with any treatments aimed at the neural circuits involved in addiction.
Now, however, researchers at the Medical University of South Carolina in Charleston may have come up with a treatment that successfully targets these brain circuits.
The researchers, supervised by Colleen Hanlon, Ph.D., managed to successfully use a noninvasive brain stimulation technique called transcranial magnetic stimulation (TMS) to blunt the brain’s response to the appeal of alcohol and cocaine in chronic users. They carried out two experiments simultaneously, both led by first study author Tonisha Kearney-Ramos, Ph.D. One study involved 24 participants who suffered from alcohol use disorder, and the other involved 25 participants who suffered from cocaine use disorder.
The participants had one session of TMS and one control session that imitated the TMS session but without actually delivering any stimulation to the brain. TMS allows the specific targeting of certain brain areas. In these experiments, both groups received stimulation focused on a region of the brain which is key for addiction and reward-processing: the ventromedial prefrontal cortex.
After the sessions were completed, Kearney-Ramos and colleagues used a functional MRI to scan the participants’ brains in order to assess their response to drug cues such as seeing a liquor bottle. The brain’s reactivity to drug cues seemed to have been significantly reduced by TMS.
“Since cue reactivity has previously been associated with abstinence,” explains Dr. Cameron Carter, editor of the journal that published the findings, “these [findings] suggest a common mechanism for treatment effects across disorders.”
“This is the first sham-controlled investigation to demonstrate, in two populations, that VMPFC [stimulation] can attenuate neural reactivity to drug and alcohol cues in frontostriatal circuits,” says Kearney-Ramos.
Hanlon weighs in, saying “Here, for the first time, we demonstrate that a new noninvasive brain stimulation technique may be the first tool available to fill [a] critical void in addiction treatment development.”
“These results,” the study authors conclude, “provide an empirical foundation for future clinical trials that may evaluate the efficacy, durability, and clinical implications of VMPFC [stimulation] to treat addictions.”