Can Deep Brain Stimulation Cure Addiction?
Can Deep Brain Stimulation Cure Addiction?
Deep brain stimulation sounds a bit intimidating, if not downright scary. And, unless you’re a neuroscientist or science news junkie, you’ve probably never heard of it.
In reality, deep brain stimulation—DBS—is a relatively simple neurosurgical procedure that can be used to treat a variety of disorders originating from abnormal brain activity. Since the 1960s, deep brain stimulation at low frequency has been used to treat chronic pain. In 1987, scientists discovered that high-frequency stimulation of the thalamus could be used to treat the tremors found in movement disorders, such as Parkinson’s disease (PD). Approved by the FDA to treat PD in 2002, DBS is also approved to treat other movement disorders, including essential tremor and dystonia. It was FDA-approved to treat obsessive–compulsive disorder (OCD) in 2009, and it is increasingly being used in research studies to treat a host of other disorders, including but not limited to epilepsy, Tourette’s syndrome, severe depression, cluster headaches, obesity, and drug addiction.
How does it work?
The basic premise is that DBS either inhibits or excites deep brain structures to alleviate abnormal patterns of neuronal firing. “You can think of it as a pacemaker for the brain,” says Dr. Nader Pouratian, director of the UCLA Neuromodulation for Movement Disorders and Pain Program. He admits that they are still not exactly sure how it works and what areas of the brain it targets in the case for using it to treat movement disorders like PD.
“The short answer is, we don’t know,” Pouratian says. “We do know that it changes the pattern of activity in the brain.” As to what neurons are being targeted, “unfortunately, we don’t know exactly.” He says that more recent studies have shown that DBS not only targets cell bodies, but also the surrounding fibers—which has great importance for treating diseases like addiction that involve multiple brain pathways. “There’s an increased awareness that when we’re stimulating a certain point of the brain, it probably causes widespread changes in networks involved in that region—so we’re modulating a network in the brain” and not just a single group of brain cells.
During DBS, electrodes are surgically implanted in the brain. A battery pack is implanted in the neck, and wires are implanted that connect the electrodes to the battery pack. The battery-controlled generator is programmed to stimulate the electrodes to deliver electrical impulses to whatever areas of the brain are selected for target, changing this area’s firing pattern. The process is personalized for every patient’s unique brain anatomy, individual symptoms, and specific disease.
While it is still a last-resort treatment, UCLA is at the forefront—at their clinic and others like it, DBS is growing in popularity as success rates for treating PD and movement disorders increase. At the UCLA pain program, they offer DBS for treating Parkinson’s disease, dystonia, and essential tremor, as well as OCD. They also offer it for chronic pain, Tourette’s syndrome, and cluster headaches—these, however, are all off-label, meaning the FDA hasn’t approved them yet.
Focus on addiction
German psychiatrist and researcher Jens Kuhn of the University of Cologne accidentally discovered DBS as a treatment for addiction. In 2006 Kuhn tried DBS on a patient with panic disorder, but instead of working on that, it actually helped him cut back on the amount of alcohol he drank. Over the next several years, Kuhn’s group published the first reports on the benefit of DBS stimulation of the nucleus accumbens—a region involved in addictive behavior—in smoking and drinking. “Recent valid animal studies show significant induced improvement in cocaine, morphine, and alcohol addiction behavior following DBS of the nucleus accumbens,” says Daniel Huys, who works alongside Kuhn.
Indeed, a search of the literature reveals that individual case reports have shown successful use of DBS in alcohol and heroin addiction. Research studies have tested using DBS for alcohol, cocaine, opioid, tobacco, binge eating, morphine, and heroin abuse. Still, these are early days, and from a clinical standpoint, DBS has a long way to go when it comes to treating addiction.
Apart from a handful of research groups (namely in China, Germany, the Netherlands, and the US) who have published a very small number of case reports using DBS to treat primarily alcohol and heroin addiction, Wayne Hall says the interest in using DBS to treat addiction isn’t great. “I suspect that this is largely because DBS is seen as a very expensive, high-technology intervention for a small minority of patients,” says Hall, who is the director and chair of the Centre for Youth Substance Abuse Research at the University of Queensland in Australia.
No clinical trials have been published to date. “I think that this has been because researchers have struggled to find suitable candidates for such trials, not that many patients are interested, and the results in some of these [case studies] have been a bit underwhelming,” Hall says. Judy Luigjes of the Academic Medical Center at the University of Amsterdam had planned to do a clinical trial of DBS in addiction, but she reported that her group struggled for two years to find a single candidate for DBS. “Overall we found it very difficult to recruit patients for this treatment,” she says. “There is quite a bit of hesitancy to refer patients for this kind of treatment among clinicians. It is an invasive procedure, and I think not every clinician favors the view of addiction as a brain disease and DBS as a treatment.”
According to clinicaltrials.gov, there are currently four clinical trials underway for DBS in addiction, including treating opiate relapse, severe alcohol addiction, severe opioid addiction, and refractory alcoholism. Kuhn’s group is running one of them, a randomized double-blinded, sham-controlled study using DBS to treat severe opioid addiction. Other proof-of-concept studies of DBS continue for use in pain, epilepsy, tinnitus, OCD, depression, and Tourette’s syndrome, as well as in eating disorders, addiction, cognitive decline, consciousness, and autonomic states.
Deep brain stimulation is a last-resort therapy. That means before considering this surgery, patients must have tried medications and other therapies and not responded well. Who’s to say that an addict has actually exhausted all his resources before “giving up” and looking toward DBS?
There can be complications to the surgery, too—often, however, they are so minimal as to be ignored, says UCLA’s Pouratian. The biggest problem might be the fact that the surgery targets networks, which could have far-reaching effects, and addiction involves many pathways to the same disease.
The success of DBS treatment is inextricably linked to reliable feedback from the patient—what happens if an addict relapses during treatment? Or, decides that the therapy is no longer worth the effort? “Heroin- and alcohol-addicted persons are usually much more ambivalent about whether to stop using heroin or alcohol than Parkinson’s patients are about treating their movement disorders,” Hall quips.
After the surgery, there is a period that can take up to months when patients visit the hospital regularly and together with the clinician, search for the optimal settings by reporting back the changes that they observe in their symptoms. “It is a treatment that requires quite a bit from patients because it takes some time and effort to find the right settings,” Luigjes says. “Compared to other psychiatric disorders it seems especially difficult for patients with a severe chronic addiction to commit to this kind of intensive treatment. Many patients showed initial interest but stopped somewhere during the screening procedure often without giving a reason. It seems especially difficult for people who have little stability in their lives or no people around them that can support them.”
Over last five years, UCLA’s Pouratian confirms that much progress has been made in the field in beginning to recognize psychiatric diseases as diseases of abnormal circuitry in the brain, and “recognizing that we can target therapies to fix those circuits.”
However, proving efficacy will be the hardest part for making DBS a mainstream treatment for addiction. Because they had a lot of difficulties recruiting patients for the trial, Luigjes questions “the feasibility of larger trials and establishing [DBS’] efficacy,” she says. “I am not sure if it will be a definite treatment, however if so, I think it will not be in the near future.”
Hall sees it being trialed for other intractable psychiatric disorders. OCD seems of most interest at the moment. He says that interest has declined for using DBS for depression because of poor trial results, but it could be resuscitated if more promising sites of stimulation are identified. “I would predict that if DBS is used for addiction in the future it will only be used in a minority of patients and will remain a niche treatment for addiction rather than becoming a mainstay form of treatment as it looks like it’s becoming for Parkinson’s disease and other movement disorders.”
UCLA’s Pouratian says that “realistically, the earliest it would be available would be five years from now.” He believes it will take an advocate with a strong interest in bringing addiction treatment to the forefront, as well as more careful clinical trials. “I think it’s a promising therapy for a spectrum of diseases, including addiction, but we need to be a little bit more methodical or careful—every time a trial does not work, the negative repercussions [do] far greater harm to the field.”