Diet chart for a dementia prone patient

Hey guys, my dad is 69 years ago and he has been diagnosed with the early stage of dementia disease. She doesn't follow her day-to-day routine and appetite. It's sometimes not an easy task to handle her.  On the either side, I don't have an idea on what kind of food usually the dementia patients are preferred to eat (must be healthy for them too). The sad part is, due to my tight work schedule can't even spare a day for her. I'm planning to hire a good caretaker from a Toronto-based health service provider so they can take a good take care of her. I don't think so I could manage everything simultaneously. Still I wanna hear some good responses. what are the recommended food which can help to improve brain health