In China, a brain implant trial participant developed a gambling addiction

The outlet Beijing News on January 15 published an investigation into side effects observed during trials of deep brain stimulation (DBS) used to treat opioid addiction.

DBS trial for addiction treatment

The clinical trial was conducted in 2021–2022 and aimed to suppress cravings for narcotic substances.

Participants had electrodes implanted into the nucleus accumbens, a brain region responsible for the reward system, as well as a pulse generator placed in the chest.

Purpose and mechanism of the method

The deep brain stimulation (DBS) method involves delivering electrical impulses to brain structures associated with addictive behavior.

Stimulation of the nucleus accumbens was intended to reduce opioid cravings and prevent relapse.

Story of a trial participant

Development of gambling addiction

One of the 60 participants, identified under the pseudonym Zhang Dayu, experienced marked behavioral changes after the device was activated.

According to the investigation, he developed a gambling addiction and lost about $28,000, despite previously only occasionally buying scratch cards for amounts of $15–30.

Psychiatric consequences

After stimulation began, Zhang Dayu experienced episodes of mania, increased impulsive urges, and loss of control.

During his participation in the project, he was hospitalized in psychiatric facilities five times, and a year later he experienced a relapse of drug addiction.

Side effects and doctors’ response

Acknowledgment of a link to the trial

Surgeon Wang Wei, who performed the operation, acknowledged a connection between the side effects and the intervention.

According to him, stimulation of the nucleus accumbens can trigger manic states and other behavioral reactions.

Scale of the issue among participants

Journalists contacted 14 trial participants.

Of these, eight people reported side effects they considered unacceptable, while three others noted reactions that did not interfere with daily life.

Regulatory status of the technology

In December 2025, the DBS system for treating opioid addiction received regulatory approval from China’s National Medical Products Administration (NMPA).

The approval was granted after completion of clinical trials and review of the submitted data.