Does deep brain stimulation induce apathy in Parkinson’s disease?
Kirsch-Darrow L, Mikos A, Bowers D. (2008) Does deep brain stimulation induce apathy in Parkinson’s disease? , 2008 May 1;13:5316-22
This article is a review of the literature regarding apathy, a non-motor symptom, of PD, particularly looking at its relationship to DBS. The authors define apathy as “a primary lack of motivation…[with] behavioral, cognitive, and emotional symptoms.” Estimates of the prevalence of apathy ranged from 38-51% of PD patients (not specific to DBS) and can be distinguished from depression (a condition that has some symptom overlap). The authors posed several hypotheses of what areas of the brain may be affected when someone is apathetic as well as what may be causing such changes (e.g. activation from the electrode that is possibly spreading to non-motor areas).
The authors of this manuscript found 7 studies that met their criteria for review and discussed each in detail regarding the strengths and weaknesses of each study. The studies had mixed results regarding how much change occurred in apathy after DBS-STN, but it is notable that none of the studies found apathy to be improved after surgery. Also, one of the more sound studies found that when comparing two surgical groups (one with PD and one without PD – the control group) the PD group had increases in apathy and the control group did not.
The authors also suggested areas for future research to address when looking at apathy, such as looking at medication reduction, electrode placement, stimulation sites (GPi vs. STN), presurgical patient characteristics, and cognitive changes in relationship to changes in apathy. They also brought up the need to use control groups, adequate apathy assessment tools/measures, and clinically significant statistical measures. Their stated goal with this article was to support advancement in quality research that helps to better understand and treat PWP.