 It gets tricky, right? Oh, absolutely. Because you have things like wisdom brushing up against decreasing cognitive function. Right. I mean, there is a lot of variability. A healthy human brain has up to 100 billion nerve cells making trillions of connections with each other. Recent research suggests a normal part of aging involves forgetting less important memories to help make room for new ones. The problem comes when normal forgetting is coupled with an abnormal process causing dementia.