Lex and Mary Duncan in their Trenton, Ontario home on Jan. 23, 2013. Lex Duncan has been caring for wife Mary Duncan at home since she was diagnosed with dementia in 2008. Currently, about 750,000 Canadians are living with cognitive impairment, including dementia, but that number is expected to double by 2031, according to the Alzheimer Society of Canada. The care will often times fall on the family members - the husband, the wife, the son, the daughter or even the grandchildren.The Duncans wouldn't have it any other way. Lex believes he can give her the best care at home, however it's not easy. "You think you'll live forever and never have any problems," says Lex, "But life ain't quite like that."