What is the cut off age requirement for deep brain stimulation?

Traditionally, we kind of set an age limit of 70 years old, meaning that beyond that we would say that maybe they should not get DBS because it might not be able to help. Over time we became more flexible with age limits, and have done DBS for patients in their mid to late 70s to help them. The amount of help DBS can give often diminishes as the patient ages.