Having a disease, including alzheimers, is not legal justification for commuting violent crimes. It may be a contributing factor, or even a cause of behavior, but it does not excuse you or make you immune from the consequences. Trying to claim it does is akin to the "he was a good kid" defense commonly claimed by banger's parents.
ORC 2901.05: Burden of proof - reasonable doubt - self-defense.
(B)(1) Subject to division (B)(2) of this section, a person is presumed to have acted in self defense or defense of another when using defensive force that is intended or likely to cause death or great bodily harm to another if the person against whom the defensive force is used is in the process of unlawfully and without privilege to do so entering, or has unlawfully and without privilege to do so entered, the residence or vehicle occupied by the person using the defensive force.