[dragonwriter]

> Now we have analyzed more than 3000 brain scans and our software’s predictions are 90% accurate.

This is really a case where the rate of false positives and negatives (and the ages of the study population) with comparison to incidence is needed, and not just a % accuracy. Just unconditionally saying “no” gives you a pretty high prediction accuracy (83% lifetime accuracy for women at 65, 91% for men at the same age, based on remaining lifetime risk of developing the disease.)