Thursday 1 September 2022

World-first study tests brain implants in humans to stop binge eating


In a first-of-its-kind pilot study, scientists have surgically implanted a device into the brains of two obese subjects suffering from binge-eating disorder. The device was designed to detect and disrupt brain signals associated with binge-eating food cravings, with promising results laying the foundations for a future where implants can control a variety of impulsive behaviors.

In late 2017 a fascinating study was published that suggested certain activity in a brain region called the nucleus accumbens could be linked to harmful impulsive behaviors such as binge-eating. The study demonstrated in mice how a brain implant could, in real-time, detect activity linked to binge-eating impulses, deliver pulses of electricity to block those signals, and subsequently stop the animals from excessive food consumption.

The idea of deep brain stimulation in humans is not entirely new. For a number of years scientists have used implanted devices to help treat patients with conditions such as epilepsy and Parkinson’s disease.

But those prior devices have generally relied on pre-programmed bursts of electrical stimulation aimed at more broadly managing patients with severe motor control problems. This new research took a completely different approach, looking to control impulsive behaviors by identifying and blocking highly specific brain activity signatures.

This new study offers the first evidence of this idea potentially working in humans. Reporting in Nature Medicine, the researchers describe the experiences of the first two human patients using this kind of brain stimulation device.

The two patients in the pilot trial had been clinically diagnosed with binge-eating disorder and were severely obese. Following a surgical procedure that implanted a brain stimulation device with electrodes targeting the nucleus accumbens, the two patients were observed for around six months.

Over that initial observation period the researchers focused on recording each patient’s brain activity, with the goal of homing in on a distinctive signature that could be associated specifically with binge-eating behaviors. This sometimes included the patients coming in to lab settings for experiments where they were presented with large buffets of high-calorie foods.

After this initial observation and recording period, the researchers switched on the implants, each encoded with the individual patient's own binge-eating neural trigger. The device is a closed loop system, meaning it is designed to switch its electrical bursts on and off independently as it senses the targeted brain activity.

The patients were monitored for another six months and the researchers indicate the devices seemed to be working well, with no adverse effects detected. Both patients reported significant drops in the frequency of binge-eating episodes, and reductions in feelings of loss-of-control. On average, each patient also lost around 11 lb (5 kg) over the following six months, with no particular direction for a dietary intervention.

“This was an early feasibility study in which we were primarily assessing safety, but certainly the robust clinical benefits these patients reported to us are really impressive and exciting,” said senior author on the study Casey Halpern.

As Halpern stressed, this initial pilot study was designed to mainly focus on safety and feasibility. So it’s too early to tell whether this kind of brain stimulation method actually works to control binge-eating, but these early indications do show the device to be safe.

In particular, the researchers noted there were challenges in finding distinct brain activity patterns that could be linked to just “loss-of-control” binge eating, and not regular eating or craving events. After months of surveillance, certain signals were identified but more work will be needed to optimize the specificity of binge-eating brain signals in humans.

Alexandra Pike, a mental health researcher from the University of York who did not work on this new research, stressed the device needs significantly greater specificity in how it functions before it can be used on more people. Despite calling the new findings “promising,” Pike said the device in its current form was way too active, sending bursts of stimulation to the patients’ brains hundreds of times a day outside of actual eating experiences.

“… the results suggest that the pattern of brain activity detected happens around 50-60% of the time when patients are awake, not only when the patients are experiencing loss-of-control eating, which means they are being stimulated perhaps more than is necessary (roughly 400 times per day) with the current settings,” Pike said.

So, although this research does gesture toward a future where it could be possible for brain implants to regulate impulsive behaviors such as excessive eating, there is a lot more work to do before we understand exactly how to do this. This particular research is ongoing, and more subjects are set to be recruited to further refine this technology.

The new study was published in the journal Nature Medicine.

Source: Penn Medicine

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