DOT : Full stop, i.e the end... Thus Dotage is old age,near to death!
Due to old age DOTS are not visible.
When u hav weak memory ie in old age, u tak dosage(relate it with dotage);-)
do + age
'Dot' after 60 years of 'age' you start to lose your brain!
dot(e) age - when someone is senile they have reached they age where they require doting from others
Do it at Age; self explanatory.
In the dotted age we loss our mental ability
dotage - in old age you dote on your grandchildren and act mad and child-like and senile. So it is 'dote''age' and also 'do old age'