State of mind. The way you type, scroll, tap on your smartphone could help doctors detect signs of depression, mental illness and overall cognition, as long as you’re using the Mindstrong app. A trio of doctors developed the app and have been gathering data for years. Their studies show that how you use your phone can tell doctors a lot about your mental state. The idea is that the data the app collects gets encrypted, is sent to your doctor, who, if she sees signs of mental distress (even before you do), could intervene. The App isn’t available for all yet and Mindstrong has some privacy concerns to work through, but it could point the way for a whole class of apps that actually are good for you.