Hello (M) and (N) this is Samuel.

You are asking about alternate realities and how and why people experience them.
This is a complicated business as it can be looked at in many ways. We will confine ourselves with looking at older people whose faculties diminish as they age. Each part of a human body ages at different times and obviously each individual experiences their own blueprint.

To focus on the brain, it tends to last a long time before brain disease occurs, as compared to other organs of the body. This is because, when this happens then the person loses their independence. When brain disease really takes hold they cannot think or act for themselves. What happens is that the connections in the brain for, say, decision making, will not work as they should. Different parts of the brain have their own functions and the part that deals with alternate realities is one that often fails as the person gets to old age.

It is as if they play out their fears and fantasies and believe they are real.