My Husband Was Diagnosed With Alzheimer's A Year Ago. He

My husband was diagnosed with Alzheimer's a year ago. He has been of 10 mg of Lexapro for several years for depression and anxiety. A neuropsychologist has looked at some tests and felt he was very depressed and needed a higher dose. Neither our family doctor or I feel that he is depressed more than anyone would be with that diagnosis. In short, the Lexapro was increased to 20 mg and he is sleeping all the time. 10 hours at night and constant napping all day. I would like to cut back to the 10 mg. Your advice?