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Treating OCD With Gamma Rays Is Really Hard

Researchers are advancing novel treatments for severe OCD.

by Steph Yin
Apr 20 2015, 10:55am

​Image: ​Eric Gilliland/Flickr

Of the approximately 3 million Americans with obsessive-compulsive disorder, 2​0 to 50 percent experience a form debilitating enough to be termed "severe" OCD. People with severe OCD can have trouble maintaining jobs and relationships, are often housebound, and can be at high risk for suicide despite years of aggressive treatment with first- and second-line medications and behavioral therapies. For some of these patients, surgery might be a solution.

Nicole McLau​ghlin is a clinical neuropsychologist at Butler Hospital, a psychiatric hospital affiliated with Brown University in Providence, Rhode Island. Her team performs the two primary surgeries used to treat severe (sometimes called "intractable") OCD: ablative brain surgery and deep brain stimulation.

In ablative ​brain surgery, a doctor makes small, targeted lesions in the brain. These lesions disrupt malfunctioning circuits thought to cause OCD symptoms. In deep brain stimulat​ion, a doctor implants electrodes in the patient's brain to "rewire" similar circuits.

McLaughlin recently received a g​rant from the National Institutes of Health to study the brain circuitry impacted by ablative brain surgery. Her team is refining a non-invasive technique for creating brain lesions, called gamma knife r​adiosurgery. Gamma knife radiosurgery uses highly focused radiation to create lesions in the brain, thereby eliminating the need to open up or drill into a patient's skull. McLaughlin has seen the technique pay off: she said that roughly 60 percent of her patients have experienced a 35 percent or greater reduction in their OCD symptoms, allowing them to reestablish more functioning lives.

McLaughlin photo1.jpg

Image: Nicole McLaughlin

MOTHERBOARD: Your work involves making changes to the brain to improve OCD symptoms. What do we know about OCD in the brain?
Nicole McLaughlin: The brain is very complex and we still haven't figured everything out, but there are certain areas of the brain we know play a role in OCD symptoms. Research studies consistently show changes in specific brain areas called the striatum and prefrontal cortex. Multi​ple studie​s have shown that people with OCD have enhanced connectivity between these regions of the brain compared to control subjects.

What do you mean by enhanced connectivity?
It's normal for deep areas of your brain to send signals to the front area of your brain when something bad happens. If you see a snake on the ground, those signals make you think, "This is bad, this is bad." In patients with OCD, however, those connections can be too strong. So the "this is bad, this is bad" response is amplified, and extends to things that aren't necessarily that bad. In situations where the brain might normally say, "No, no it's not so bad, don't worry about it," people with OCD continue to worry.

So what does ablative brain surgery do?
The ablative brain surgery we do involves making small lesions in the internal c​apsule, a small region of the brain that signals travel through on their way from the thalamus, deep in the brain, to the prefrontal cortex. We have proof that lesioning this pathway can actually change OCD symptoms.

Our procedure uses gamma radiation, which has traditionally been used for things like brain cancer, to create a lesion on a target area in the brain. The gamma knife looks kind of like an MRI machine. Patients slide into it and lay there for two to three hours. The benefit is we don't have to open up their skull.

The gamma knife used by McLaughlin and her team

What about deep brain stimulation?
In deep brain stimulation, a battery is implanted in the patient's chest or abdomen, and that battery is connected to wires that go up under the skin into the brain. Those wires are connected to small electrodes, which are placed in the internal capsule and deliver electrical stimulation. We can control the stimulation coming out of the electrodes, so deep brain stimulation gives us flexibility in terms of manipulating parameters like intensity, polarity, and location of delivery.

What are some differences between the gamma knife and deep brain stimulation procedures?
They are both quite safe, and about equally effective. Roughly 60 ​percent of patients with severe OCD get better with either one. Deep brain stimulation is a little more flexible and theoretically reversible since patients can take the electrodes out at any time. The drawback is you always have something in your head. Similar to someone with a pacemaker, you have to worry about the electrodes when going to the airport or getting an MRI. You also have to remember to recharge and occasionally replace the battery.

Lesion surgery has been around for much longer. The first gamma knife procedure for OCD was done in the 1980s, and we have been doing it at Butler since 1993. The first studies of deep brain stimulation for OCD took place in the late 1990s, and I believe the first pa​tient to get deep brain stimulation for OCD at Butler was treated in 2001. Since then, we have been continually improving the outcome and reducing the side effects of the procedure. The nice thing about lesion surgery is that once you've had it, you're done. You don't have to worry about being tethered to a device. From a research standpoint, another benefit of lesion surgery is that we can do MRIs on patients after the procedure to see changes in the brain.

How do the procedures differ in cost?
The out-of-pocket cost for deep brain stimulation is around $80,000 for the initial surgery, and it can be $15,000 to $20,000 to replace the battery every few years. So it gets quite expensive. But Medicare will typically pay for at least the initial surgery.

The out-of-pocket cost for the gamma knife is much cheaper. It differs depending on the hospital, but at our site a typical procedure might cost $25,000. Medicare has continually denied us when we ask them to pay for the gamma knife.

"We've had such an improvement in technology, which has helped us target procedures."

Why doesn't Medicare pay for the gamma knife?
They say they won't cover it because it is "experi​mental," but there are so few cases that it is almost impossible to get it approved. I believe the policy actually goes back to a repor​t commissioned by Congress 30 or 40 years, which cautions against brain lesion surgery and other types of psychosurgery. Certainly going back a very long time ago, there were surgeons who were not so careful about things, like Walter​ Freeman, who would do lobotomies on people who probably shouldn't have had them.

That's nothing like we do now. We've had such an improvement in technology, which has helped us target procedures. That's also why we're so careful that patients consent themselves and we go through a rigorous approval process with strict eligibility criteria.

This is something I want to work on. We are starting to see so many patients who could benefit from the gamma knife. To me, if we can help even one patient who can't pay for it, it's worthwhile.

What drew you to studying OCD?
I was initially interested in neuropsychology because my mother is a special education teacher, and I would help her in her classroom when I was younger. My father is a physician assistant in neurosurgery, so I would often hear about the brain. I did my master's thesis on ADHD, but my dissertation looked at cognitive functioning in different psychiatric disorders. After my fellowship, I started working with patients with OCD. The patients themselves are a pleasure to work with, and I enjoy studying novel, cutting-edge treatments. OCD is an interesting disorder because you can see direct connections with how the brain might be causing these behaviors to occur.

What's next for OCD research?
Our group is starting to explore more non-invasive electrical stimulation techniques, such as transcranial direct cu​rrent stimulation, which delivers low electrical currents to the brain through electrodes on the scalp. Never mind the fact that these techniques are easier and less expensive than invasive surgery, they could also potentially open new options to a large range of patients with OCD. They might, for instance, help people who struggle with a form of OCD that's significant but not severe enough to be eligible for the gamma knife or deep brain stimulation. OCD is a very complex, heterogeneous disorder with different subtypes that we don't fully understand yet. There's still a lot of room for improving treatment options and outcomes.

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