Deep brain stimulation (DBS) may be an effective option for patients with treatment-resistant schizophrenia (TRS), new research suggests. However, until further studies are conducted, the treatment should only be considered for the most severe cases.
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The first clinical trial to assess DBS in this challenging patient population included eight patients initially randomly assigned to receive electrode placement in one of two locations in the brain. Once a clinical response was achieved and participants were stabilized, they were randomly assigned to a second crossover phase.
Preliminary findings from the first phase of the DBS-SCHIZO pilot study, which were reported in 2017, showed promising efficacy.
The newly released final results revealed an association between DBS and significant improvements in Positive and Negative Symptoms Scale (PANSS) scores, as well as reductions in doses of antipsychotic medication. Moreover, the effect reversed when the electrode was switched off.
“DBS may be a potential option for severe treatment-resistant schizophrenia patients,” lead investigator Iluminada Corripio, MD, PhD, department of psychiatry, Hospital de la Santa Creu i Sant Pau, Barcelona, said during her presentation at the virtual congress of the European College of Neuropsychopharmacology. The new data were updated results of a study published in EBioMedicine earlier this year.
Dr. Corripio underlined that it is important to balance the risks and benefits of the intervention. DBS is “not useful for all phenotypes,” and benefits have been seen in patients with hallucinations but not in those with a disorganized phenotype, she added.
High economic burden
Managing TRS is challenging and is associated with a high clinical and economic burden, Corripio noted. Relapse rates can reach 80%, increasing resource use by between 200% and 900%.
There is a strong rationale for studying the use of DBS in schizophrenia, because schizophrenia shares a neurologic basis with other neurologic and psychiatric disorders centered around the cortical-striatal-thalamic-cortical circuit, said Dr. Corripio.
The study included eight patients with a DSM-IV-TR diagnosis of schizophrenia whose conditions were resistant to at least two different atypical antipsychotics and who had not responded to clozapine monotherapy, combination therapy, or electroconvulsive therapy.
All were randomly assigned in a 1:1 ratio to DBS electrode implantation in one of two locations. Investigators chose the nucleus accumbens (NAcc), because recent studies have shown that DBS can increase dopamine levels there, and the subgenual anterior cingulate cortex (ACC). Deactivation failure in the ACC region has been observed in patients with schizophrenia and other mental illnesses.
Stimulation began 48-72 hours postoperatively with unilateral left stimulation at 2.5 volts. It was increased in 0.5 volt increments to a maximum of 7.5 volts. Patients who did not respond were switched to bilateral stimulation.
Follow-up was conducted every 2 weeks for up to 20 months. The study’s primary outcome was a symptomatic response, defined as an improvement of at least 25% on the PANSS.
Once that was achieved, patients could enter a second randomization phase in which they were assigned, in a 24-week, double-blind crossover design, to on- or off-treatment DBS arms such that patients received stimulation for 12 weeks before the device was turned off for 12 weeks, or vice versa.
Those who experienced relapse while off treatment were crossed over to the on-treatment arm; those who experienced relapsed while on treatment were withdrawn from the study. The patients’ average age was 42.5 years, and 50% were women. All were taking clozapine in combination with another antipsychotic.