Few things are more important than having a healthy brain—but what does “brain health” mean, exactly? It feels like every day I encounter a new multivitamin, health app, or wearable with some version of the promise that the product will “support cognitive function,” “sharpen focus,” and of course, “improve brain health.” As long as these products don't make claims about treating specific diseases, the FDA doesn’t require a strict definition of what that actually means. As a result, “brain health” can mean different things to a supplement company, a meditation app, or an actual neurologist. Meanwhile, consumers are left grasping at straws trying to evaluate these claims. Before you can judge whether a product delivers what it promises, you need to understand what “brain health” actually mea...