That claim falls apart as soon as it touches reality: there are a _lot_ of people who are involved in the drug trade, now and in the past. At some point, one of those people would definitely have had a CT or an MRI on their skull (e.g. my dentist does a whole head CT every 5 years as part of the normal process and insurance pays for it). Surely _one_ of those people would have noticed a brain implant.
This sounds extremely made up.