On 2015 Jun 25, David Keller commented:

Does Deep Brain Stimulation slow the progression of neurodegeneration in early Parkinson disease?

The authors report that "Subjects receiving an earlier STN-DBS showed a sustained improvement in the activities of daily living and motor complications, never reaching the severe levels of disability reported by Late-Stimulated patients at the time of surgical selection." Did this sustained level of symptom improvement require ongoing increases in DBS stimulation parameters (such as total daily stimulation current)? The need for increasing DBS stimulation to maintain a constant level of symptom improvement implies continued progression of the patient's underlying neurodegeneration. On the other hand, if sustained symptom improvement was achieved while requiring constant or decreasing amounts of electrical brain stimulation, this might reflect slowing or reversal of the neurodegenerative process.

It would be informative to assess the neurological status of the subjects who received early DBS, with their stimulators turned off, and track these UPDRS scores over time. If the rate of worsening of their stimulator-off UPDRS scores is slower than the rate of worsening for comparable patients who have not received DBS, that would imply possible disease-altering effects for DBS in early PD. Was the crucial stimulator-off UPDRS data collected in this study, and, if so, what do they tell us about how DBS affects the rate of neurodegeneration?

On 2015 Jun 25, David Keller commented:

Does Deep Brain Stimulation slow the progression of neurodegeneration in early Parkinson disease?

The authors report that "Subjects receiving an earlier STN-DBS showed a sustained improvement in the activities of daily living and motor complications, never reaching the severe levels of disability reported by Late-Stimulated patients at the time of surgical selection." Did this sustained level of symptom improvement require ongoing increases in DBS stimulation parameters (such as total daily stimulation current)? The need for increasing DBS stimulation to maintain a constant level of symptom improvement implies continued progression of the patient's underlying neurodegeneration. On the other hand, if sustained symptom improvement was achieved while requiring constant or decreasing amounts of electrical brain stimulation, this might reflect slowing or reversal of the neurodegenerative process.

It would be informative to assess the neurological status of the subjects who received early DBS, with their stimulators turned off, and track these UPDRS scores over time. If the rate of worsening of their stimulator-off UPDRS scores is slower than the rate of worsening for comparable patients who have not received DBS, that would imply possible disease-altering effects for DBS in early PD. Was the crucial stimulator-off UPDRS data collected in this study, and, if so, what do they tell us about how DBS affects the rate of neurodegeneration?