Chinese patients who underwent deep brain stimulation (DBS) as part of clinical trials to treat opioid addiction are reporting uncontrollable sexual urges, compulsive gambling, and other behavioral changes that they believe were triggered by the treatment.

In a Jan. 15 investigation, state-run The Beijing News reported that eight of 60 patients in a nationwide clinical trial experienced side effects they described as “intolerable.” The trial was conducted between 2021 and 2022 by SceneRay, a Chinese medical device maker. 

Patients had electrodes implanted in the nucleus accumbens — a brain region linked to pleasure, motivation, and addiction. The electrodes were connected to a pulse generator  — often described as a “brain pacemaker” — implanted into their chests. The company claimed that electrical stimulation could reduce drug dependence.

A global leader in DBS research, China conducted its first DBS clinical trial for drug addiction at Shanghai’s Ruijin Hospital in 2019 on a group of patients addicted to methamphetamine. The treatment had previously been approved for use in movement disorders like Parkinson’s, and studied for use in mood disorders such as depression.

One patient, identified by the pseudonym Zhang Dayou, enrolled in the opioid addiction trial at a major hospital in southwestern Sichuan province, after more than a decade of heroin addiction. 

Instead, after the device was activated, he began gambling compulsively, accumulating debts of about 200,000 yuan ($28,000), and was admitted to psychiatric hospitals five times. Within a year of implantation, he relapsed.

At Zhang’s request, doctors eventually turned off the device. He said the change was immediate and overwhelming. “I grabbed the doctor’s hand and fell to the ground,” he told domestic media. “I couldn’t endure it being turned off any more than it being turned on. I begged them to switch it back on. Only then did I feel alive again.”

Zhang later sought to sue SceneRay, but said three lawyers declined to take the case, citing the difficulty in proving a causal link between the implant and his behavioral changes.

Other participants reported slowed reaction times, anxiety, mania, and heightened sexual urges including pornography obsession, after their devices were activated.

One patient was prosecuted for sexual misconduct after undergoing DBS and argued that the implant had influenced his behavior. However, the court rejected the claim, ruling that there was no definitive medical evidence establishing causality.

SceneRay defended the clinical trial, saying its neural stimulation system was approved by China’s National Medical Products Administration in 2017 and that the clinical trial had passed the required ethical review.

The trial’s informed-consent documents required the purchase of clinical research liability insurance. But such policies typically exclude psychological or mental harm unless accompanied by severe physical injury.

Wang Wei, Director of Neurosurgery at West China Hospital of Sichuan University and lead surgeon on Zhang’s case, said stimulation of the nucleus accumbens can produce wide-ranging effects. He said adverse reactions can sometimes be mitigated by adjusting the electrical stimulus, though several participants said such changes brought little relief.

As of Jan. 15, 11 participants had reported that their brain pacemakers had been turned off.

Editor: Marianne Gunnarsson.

(Header image: Shijue AIGC/VCG)