The effect of deep brain stimulation on the non-motor symptoms of Parkinson’s disease: a critical review of the current evidence

Abstract

The benefit of deep brain stimulation (DBS) in controlling the motor symptoms of Parkinson’s disease is well established, however, the impact on the non-motor symptoms (NMS) remains to be elucidated, although the growing investigative efforts are promising. This article reviews the reported data and considers the level of evidence available with regard to the effect of DBS on NMS total burden and on the cognitive, neuropsychiatric, sleep, pain, dysautonomic, and weight domains. Multiple case series suggest that DBS improves the burden of NMS by reducing prevalence, intensity, and non-motor fluctuations. There is level I evidence on the effect of DBS on cognition and mood. Slight cognitive decline has been reported in most class I studies, although the functional effect is probably minimal. Two randomized prospective studies reported no change in depression while improvement of anxiety has been reported by a class I trial. Prospective cohort studies point to improvement of hyperdopaminergic behaviors, such as impulse control disorders, while others report that hypodopaminergic states, like apathy, can appear after DBS. There is only class III evidence supporting the benefit of DBS on other NMS such as nocturnal sleep, pain, dysautonomia (urinary, gastrointestinal, cardiovascular, and sweating), and weight loss. Although preliminary results are promising, randomized prospectively controlled trials with NMS as primary end points are necessary to further explore the effect of DBS on these often invalidating symptoms and offer conclusions about efficacy.

Beneficial effects of bilateral subthalamic stimulation on alexithymia in Parkinson's disease

“…Our results are in line with previous studies that reported beneficial effects of STN‐DBS on anxiety, subjective sleep symptoms and non‐psychiatric non‐motor symptoms including dysautonomia . Furthermore, our results are in line with studies reporting negative results on DBS effects on mania or apathy and, in congruence with these, we observed that apathy and QoL change scores correlate significantly .…”

Quality of life outcome after subthalamic stimulation in Parkinson's disease depends on age

“…As a result of the design of our database as a prospective, observational study, at the follow‐up only clinical ON states (MedON/StimON) were recorded. Systematic follow‐up examinations of motor states with and without medication and DBS could be informative to assess patients' nondopaminergic, nonmotor, and axial characteristics, which may contribute to their QoL . The cognitive assessment is limited as the MMSE is not a PD‐specific instrument and its psychometric characteristics in PD are poor.…”

Invasive and Noninvasive Brain Stimulation in Parkinson's Disease: Clinical Effects and Future Perspectives

“…With respect to specific NMS, DBS can improve sleep quality through reduction of sleep fragmentation, reduced arousal episodes at night, and improved nocturnal mobility. Nevertheless, the severity of the daytime sleepiness and the rapid eye movement sleep behavioral disorder are unchanged . Both GPi and STN DBS relieved pain in patients with PD with sustained long‐term effects.…”

“…For mood changes, there is no association between DBS and depression or suicide ideation . It should be noted that cognitive or behavioral changes may be affected by the preoperative condition, patient selection, electrode trajectories, and location of stimulation contacts …”