What’s next for deep brain stimulation in OCD?
Current status of procedure
While Dr. Denys focused on the near future of DBS for OCD, another speaker at the session, Sina Kohl, PhD, addressed DBS for OCD as it exists today, particularly the who, how, and where.
The “who” is the relatively rare patient with truly refractory OCD after multiple drug trials of agents in different antidepressant classes, one of which should be clomipramine, as well as a failed course of CBT provided by an expert in CBT for OCD, of which there are relatively few. In a study led by investigators at Brown University, Providence, R.I., only 2 of 325 patients with OCD were deemed truly refractory (J Neuropsychiatry Clin Neurosci. 2014 Winter;26[1]:81-6). That sounds about right, according to Dr. Kohl, a psychologist at the University of Cologne, in Germany.
The “how” is to deliver DBS in conjunction with CBT. Response rates are higher at centers where that practice is routine, she added.
The “where” is an unsettled question. In Dr. Kohl’s meta-analysis of 25 published DBS studies, electrode placement in four different DBS target structures produced similar results: the nucleus accumbens, the anterior limb of the internal capsule, the ventral striatum, and the subthalamic nucleus. Stimulation of the inferior thalamic peduncle appeared to achieve better results, but this is a sketchy conclusion based upon two studies totaling just six patients (BMC Psychiatry. 2014 Aug 2;14:214. doi: 10.1186/s12888-014-0214-y).
Recently, Belgian investigators have reported particularly promising results – the best so far – for DBS targeting the bed nucleus of the stria terminalis (Mol Psychiatry. 2016 Sep;21[9]:1272-80).
Bilateral DBS appears to be more effective than unilateral.
Dr. Kohl and her colleagues in Cologne recently completed a study of DBS in 20 patients. She noted that it took 5 years to collect these 20 patients, underscoring the high bar that’s appropriate for resort to DBS, even though the therapy is approved for OCD by both the Food and Drug Administration and European regulatory authorities. Forty percent of the patients were DBS responders, with a mean 30% improvement in Y-BOCS scores. That’s a lower responder rate than in Dr. Denys’s and some other series, which Dr. Kohl attributed to the fact that in Germany, postimplantation CBT is not yet routine.
Asked about DBS side effects, the speakers agreed that they’re transient and fall off after initial stimulation parameters are changed.
“The most consistent and impressive side effect is that initially after surgical implantation of the electrodes and stimulation of the nucleus accumbens, patients experience 3 or 4 days of hypomania, which then disappears,” Dr. Denys said. “It causes a kind of imprinting, because even a decade later, patients ask us, ‘Could you bring back that really nice feeling?’ It’s 3 days of love, peace, and hypomania. It’s a side effect, but people like it.”
Dr. Denys and Dr. Kohl reported no financial conflicts of interest regarding their presentations.
