How long does a brain aneurysm take to develop? i had an mra 7 years ago and it was normal. could it develop this fast? i am 28.

Yes: Aneurysms often form in an area of focal weakness of the vessel wall, most commonly at a bifurcation of 2 vessel branches. Some people are more prone to have them, and some form for unknown reasons. They can develop at different rates for people depending on many factors including underlying connective tissue abnormalities, blood pressure, etc. I'd say 7 years is more than enough time to form.