Can getting braces really prevent headaches later in life?

No guarantees: Balancing your occlusion means less muscle imbalance, less occlusal interferences, less MFP (Myofacial Pain Dysfunction Syndrome). However there are people with ideal jaw relationships an textbook conclusions that have chronic headache problems. Don't expect miracles from any form of healthcare treatment.

No, because: Headaches can occur for many reasons and often the cause is unknown. Something as simple as dehydration can cause a headache. What we can say is that the likelihood of developing headaches from a malocclusion, especially when it creates jaw misalignment thereby stressing muscles is increased. There are other good reasons to correct your bite- better function, aesthetics and health.