Is the joke that Rose had been dead for six years and he slowly descended into Alzheimer's because he couldn't bear to be reminded of her loss so he simply will

Is the joke that Rose had been dead for six years and he slowly descended into Alzheimer's because he couldn't bear to be reminded of her loss so he simply willed himself into a disease that would give him some brief respite by making him forget until the cold embrace of death? Because it's pretty funny, if so.