“What can I do for my father's depression due to Alzheimer's?”

The answer depends partly on the stage of dementia in terms of what would be possible psychotherapeutically. Depression should certainly be fully evaluated to take into account medical factors/medications that may be related to it. Identifying pleasant activities that he would still be able to participate in would be helpful. Early in the course of the condition, supportive psychotherapy would be an important element of care. The evidence supporting the effectiveness of antidepressants in the context of dementia is not very compelling, but they are often used, and could make a big difference for some. The problem is that we do not know which antidepressants work for whom under what circumstances in the context of dementia. Given their relatively benign safety profile, I am inclined to use one if indicated.

Dear Asker,
I am not your doctor and the following is not medical advice. Consider having him evaluated by a geriatric psychiatrist, which is a psychiatrist who has special training in managing such a case. Only after a proper evaluation to confirm a diagnosis, if any, in regard to mental health, could recommendations be made. In general patients dealing with depression may be treated with antidepressant medications and/or psychotherapy depending on the individual case and partly patient preference, which you could discuss further with the geriatric psychiatrist. Best of luck.