My 96 year old father, with moderate dementia, also scratches constantly, sometimes causing sores. Like Paulette 911 said of her sister, he will find a small, raised place on his arm, neck, chest or back and pick it to death, creating bleeding, sores, scabs, and the cycle begins again. He is driven crazy by what he calls, "The Itch". It might be something different for the doctor thinks it is eczema, and it might be. He gets some relief from cortisone taken both internally and in a cream that is slathered on twice a day. I will consider all I have read here and make some changes where I can, trying to distract him, etc. Thank you all so very much.