Suggest to them to take up a hobby. Like gardening or reading.
Even before they were diagnosed with Alzheimer’s, the patient must have had a hobby that they loved doing. It is highly recommended for these hobbies to be continued even after the patient has succumbed to the disease. This way their mind will be sharpened. They may not remember anything at all, but the skills and talents they have will not be forgotten. It will automatically manifest itself, especially when presented with a familiar setup. Hobbies like gardening, reading, kniting, and the like will be more than enough to keep the patient occupied.