Age quary for 80 dd

There is no age limitation for the dependent.... 

"dependant" means—

   (i) in the case of an individual, the spouse, children, parents, brothers and sisters of the individual or any of them;

  (ii) in the case of a Hindu undivided family, a member of the Hindu undivided family,

dependant wholly or mainly on such individual or Hindu undivided family for his support and maintenance.

No.... s/he should be dependent on the assessee...

No age bar relating to dependent is there for claiming benefit of deduction under 80DD.

However disability related conditions have to be satisfied for the purpose of 80DD deduction.