Brain Fitness 101. Our brains don’t stop growing in our teens as experts once believed. Thanks to a revolutionary idea called neuroplasticity, we now know that you can generate new brain cells and form new connections at any age. Phew! That means brain training can help you improve concentration, diminish the symptoms of diseases like ADHD and even ward off Alzheimer’s and dementia. The trick is to train all major brain functions to keep those synapses synapsing—whether you’re eight or 108.