If I had a dime for every time I saw the phrase "is not a part of natural aging," or words to that effect, in connection with a named age-related disease ... well, I'd have a nice big stack of dimes. Here's one:
[Rheumatoid arthritis] is not a normal part of aging. It is a specific condition with symptoms that can't be cured, but can be managed.
"Arthritis should not be considered just a part of the aging process or a normal part of getting older"
Except that arthritis was absolutely thought to be a part of the "normal aging process" - until it wasn't. The dividing line between solemnly named condition and mysterious process of aging is utterly arbitrary; the "normal aging process" only really exists if you want to define it into existence. When you say "normal aging," you are applying a name to a collection of changes, damage, diseases and medical conditions, some of which have their own well-worn taxonomy, and some of which don't. But all changes can be identified, and medical technology developed to repair, prevent and reverse them.
Whether and what we name these undesirable changes for the worse is rather beside the point.
The mantra of "not a part of the normal aging process" is irrational. It's an irrational response to the irrational acceptance of aging as normal - folk slowly carving off one piece of "normal aging" at a time by giving it a new name and repeatedly asserting its individual nature as a thing apart from aging. It works with the funding sources and regulators, so scientists have made something of a habit of this over the years.
This is all very silly, and has to break down at some point. The Strategies for Engineered Negligible Senescence (SENS), for example, takes a good stab at breaking down the whole of degenerative aging into seven categories of condition, damage and change. All are named and known by the scientific community, if not by the average household, and anyone can jump up and say "this decay right here - that's not a part of normal aging, because we can see it, understand it and fix it!"
What's left of "normal aging" after the researchers and medical development groups have done that? Not much, and good riddance to a bad idea.