I think the first thing you need to be aware of with senility or Alzheimer's is this: is there a family history of these debilities?
Because I have found that almost all the people I've heard about or even family members have had one parent and siblings who have experienced this.
In fact, these people ALL had better than average physical health....and so this deterioration came after the age of 75. I don't know what that means. I am not an expert. But I do know that if there's this predisposition in the genetics, it will be more likely to be passed down.
And therefore, some place in the chart will be markers for this. However, these markers (natal aspects) may NOT mean this same thing for people who do NOT have this gene.
I believe both Merc and Moon have to be highly involved with difficult aspects with the outer planets.
LIN