Generally speaking, there are two tests you can take for Alzheimer's disease - one to diagnose if you currently have it, and one to predict if you might have it in the future. Testing for diagnosis involves a series of exams including a blood/urine test, comprehensive medical history, cognitive screen, and series of MRI/CAT/PET scans. Although most people will consider testing once they start noticing certain symptoms or in their later years, since age is the greatest risk factor for Alzheimer's disease, people as early as their 30's and 40's have been diagnosed with early-onset Alzheimer's disease. If you are noticing symptoms, it is important to consult with a physician right away to determine the cause. If you are not experiencing symptoms, but are wondering if you might have Alzheimer's disease in the future, you might want to consult with a genetic counselor to decide if genetic testing is right for you. Also, please note that genetic testing is not conclusive - in fact it is about 50% accurate. Going for genetic testing may or may not give you insight into your future, so it is important to understand the limitations of this kind of test before considering it. On the other hand, I want to commend you for being physical fit and healthy, and encourage you to continue doing so for as long as possible. Taking care of your physical and mental health is the single best thing you can do for yourself to promote successful aging.