A nonagenarian is a person who has achieved the age of 90. Not a bad innings and one increasingly being witnessed as our longevity steadily increases.
The mantra about Alzheimer's is that our relative risk of developing the disease increases with age with an expected doubling of incidence every five years from the age of 65 on.
That is, until you reach 90+.
The gene that has been closely affiliated with a person's risk of developing Alzheimer's disease is APOE4. Although this link is complicated by the fact that not everyone who carries the APOE4 gene will develop Alzheimer's and some people without the gene can also develop it.
However new research has indicated that if you make it through your eighties and remain physically, intellectually and emotionally well, with a positive attitude i.e. good coping skills and social connectedness then you can expect to experience a higher quality of life.
I think if I got to that age both physically and mentally intact with lots of friends to have fun with, then yes I agree, I would be much more likely to be making the most of every day, regardless of my genotype.
The majority of the participants in the study were women (87%!) with an average age of 93. Perhaps that reflects that women tend to live longer than men. Or perhaps the men were out having a good time, leaving the women to participate in the interviews, physical examinations and cognitive testing.
The bottom line is that environmental factors play a very big role in determining your outcome as evidenced by the nonagenerians more than your genetic predisposition. And that is true regardless of your age.
Ajay K. Parsaik, Maria I. Lapid, Teresa A. Rummans, Ruth H. Cha, Bradley F. Boeve, Vernon (Shane) S. Pankratz, Eric G. Tangalos, Ronald C. Petersen. ApoE and Quality of Life in Nonagenarians. Journal of the American Medical Directors Association, 2012; 13 (8): 704 DOI: 10.1016/j.jamda.2012.06.012