It seems to me that there is some responsibility on the part of an attorney drafting a new will.
This seems like reasonable advice, "wills of persons with Alzheimer’s disease are often contested on the basis that the person no longer understood what they were doing, or that undue influence was used to obtain a specific will provision, the fact and circumstances of a will being drafted or amended by a person in the early stages of the disease should specify how and where the will was made, who was in attendance, that there was medical certification that the person was still capable of making such a will or amendment to the will. After the early stages of Alzheimer’s disease, it is advisable that no new wills be created and that no significant amendments to an existing will be made. This also reinforces the general advice that wills be made and amended in a timely fashion, when all physical and mental capabilities are still intact." Dr. Eric Pfeiffer , Psychiatry.