Unless they are experimentally inducing this effect (which I doubt, as it would be unethical to induce memory loss), this is all correlation. Biological correlation.

This isn't causation. Turning 50 doesn't trigger anything. Whatever happens is happening due to other factors, and they're tracking it in, predominantly, 50ish year olds.

Correlation isn't causation last time I checked. Even biological ones.

everyone has to read this