Recommendation for device to restore brain function/prevent effects of ageing on brain

I've recently had my belief system completely turned on its head by using out micro-current devices. This things are miracle machines and I've been telling anyone who will listen about them.
My latest listener is one of my health practioners. He's a great guy who has restored himself to great health suffering from pesticide poisoning and an all around unhealthy life style.
He's 60 years old and although his physical health is great he said he still suffers from brain fog and memory problems, and it seems to be getting worse with age. I can tell he's worried about it.

He's delighted about all the miracle stories I've told him dealing with micro-current devices and is putting his faith in me to find him a device that will help out his brain.

although I have a few devices in mind I'm just scratching the surface of this type of medicine and don't want to make a recommendation just yet.

What are the best devices for not only helping induce healthy brain wave activity but also perhaps heal and restore the brain. I'm looking now at the brain tuner and this device called the earthpulser. (i believe magnetic microcurrents might be the answer as well.)