They're loosing moter skills - unable to keep hold of empty packets until a suitable place to bin them is found, 'swagger' some sort of primitive form of walking?
Are going blind - can't see litter they've dropped, can't see how messy their rooms pits are, fail to see car reverse lights and choose to stand right behind said car
Can't dress themselves - jeans hanging bellow their arses, two belts + jeans bellow their arses 
, wear hardly anything when it's cold making me feel colder
Loosing the ability to speak - revert to grunts, swearing, selective deafness
Very forgetful - can't be expected to remember how to do the most basic things, no sense of time
I'm sure I've missed a lot too
Since hitting 25 I've turned into a miserable old git 