Clearing up brain fog would involve the use of brain supplements in general. Brain supplements can improve brain function and sort of "wake up" the brain out of its fog. Brain supplements covers a wide range of supplements and includes many of the same supplements as those for memory and focus. It's often true that a single brain supplement targets all three of these issues and so will be found in all three sections.
“I also don’t have much memory of going to the counsellor who told me I was anxious. Actually, this is a common theme across all of my anxious episodes - very hazy recollections of every day details, like dates and locations, but sharp-as-tack memories of the theories and ruminations that accompanied the episodes. Anyone else experience the same?” ― Sarah Wilson