My company makes DBS devices. There are a lot of other possible indications like migraine and others where it could help too but progress is very slow. You can't "move fast and break things" with brain implants.
(I have an RNS for epilepsy. After it was implanted, my doctor got impatient waiting for it to record a seizure and reduced my meds too much. Ended up causing me to go into status for the first and only time in my life. My memory has never been the same and I'm not sure it ever will be)
