How bad is xanax for your brain

If someone does take xanax occasionally at 7 mg like once a week how damaging is that to their brain. I really enjoy taking xanax and sometimes i mix it with alcohol but never go too overboard, but i am scared of becoming really slow. I’m a naturally smart person and have always been but i feel like i’ve been slowing down recently. Don’t know if it’s the bars or if im just tired. What do you guys think