"Dementia is getting more prevalent."
It is also affecting more and more younger people - one resident is in his sixties, she said.
Masterton Mayor Lyn Patterson officially opened the new development on Thursday, cutting the ribbon and congratulating staff.
"It's a great facility, it's their home away from home."
Lyndale staff, councillors and other health-care workers from Wairarapa attended the opening ceremony.
Mr and Mrs Dunlop purchased the old Glenwood Hospital building in 2011 and turned it into Lyndale Manor.
The wing is named after Trevor Hamilton Daniell, the architect who designed it.