58 Chapter 3 In the QoL domain we found improvements on the ED-QOL (physical health), MOS-SF-36 (physical function) and SDS (responsibilities). Other QoL subscales did not show improvement, suggesting that despite the clinical improvements made, this exceptionally severely and chronically affected patient group still suffers from psychopathology of AN and comorbid disorders. Nevertheless, in clinical assessments all patients reported an improvement, despite their pathology still being significant, no requests to switch off or remove the DBS have been made. Safety & Feasibility Given the precarious health of the patients with chronic, treatment-refractory AN, the safety of DBS was a prominent interest and related directly to the feasibility of this study. Overall, the surgery was well tolerated by all patients, despite their low baseline BMI and compromised physical health. Because of the vulnerable cutaneous and hypotrophic subcutaneous layers, we implanted the neurostimulator under the pectoral muscle. During the study, no infection, hemorrhage, intraoperative adverse events or even death occurred. SAE’s were generally related to the severity of the underlying AN and its somatic complications rather than the intervention. Transient symptoms, known to appear with DBS were reported ((hypo) manic symptoms, pain at battery site and seizures). The self-reported VAS showed an increase in impulsiveness. On closer inspection a significant increase in impulsiveness can be found between DBS-On vs Off at T1, which remains throughout the remainder of the study. This effect has not been explicitly reported in any of the previous DBS in AN studies, but has been extensively documented in OCD-patients (39). However, impulsiveness due to DBS in OCD is usually transient, while our study indicates a sustained increased impulsiveness. A possible explanation is that vALIC DBS downregulates the involvement of the reward and emotion regulation circuitry (16, 40). The experienced positive reinforcement of the ritualistic behavior normally exerted by AN-patients is negated by vALIC DBS. This decreased reinforcement may make the ritualistic behavior less usable as a coping strategy, which may lead to the surfacing of underlying problems in emotion regulation. The need for alternative coping strategies, in combination with pre-existent emotion regulation problems and increased impulsiveness due to DBS, may lead to the development of new (inadequate) coping involving self-destructive behavior, which may explain some of our (S)AE’s. On the one hand, this can be interpreted as a negative effect of DBS, and it made the study challenging. On the other hand, one might also argue that the surfacing of underlying emotion regulation problems and inadequate coping, that were previously masked by eating disorder symptomatology, provides a new entry for treatment targeted at these core problems. In response to the surfacing of these emotion regulation problems induced by DBS, three out of four subjects in our study became eligible for additional psychotherapy aimed at coping and emotion regulation and showed clinical improvement on these domains. Before DBS, treatment aimed at
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