There might not be much you can do, other than ride it out. Like so many other symptoms of menopause, this one is related to falling levels of estrogen. In fact, in the past, you may have noticed this forgetfulness and muddled thinking right before you got your period, but it was fleeting. Menopause, not so much. Estrogen starts to fall in many women around age 45 and that continues until menopause ends around age 50 or so. The good news is that brain fog is temporary, according to research. Eventually, the brain adjusts to the change in estrogen and you go back to thinking clearly again.
In the meantime, try the old reliables—eat lots of fruit, vegetables, and lean protein, exercise regularly, and a get good night of sleep (not easy, I know!). If those don’t work, talk to your doctor about whether hormone therapy might be an option for you. It will replace some of the estrogen, which presumably could help with brain fog, although there’s not conclusive research yet to prove it.