Does meditation cure overthinking or does it come back?

Overthinking does not vanish for good, and expecting that sets you up for disappointment. What changes is your relationship to it. With practice, you catch the spiral sooner and step out of it faster, so it carries less weight even when it returns. Think of it as a skill you keep sharpening rather than a switch you flip once. StillMind helps you practise that catch-and-release regularly, so busy thinking becomes something you can work with instead of drown in.