The period, sometimes weeks, sometimes much longer, where your mood is better but your thinking still feels blunted. SSRIs, the most commonly prescribed class, work by increasing serotonin availability across several receptor types in the brain. They also, notably, do not reliably improve cognitive symptoms in depression. The question was whether targeting it could help address the cognitive symptoms that antidepressants often leave untouched. If you are experiencing brain fog as part of depression or its aftermath, that conversation belongs with a doctor or psychiatrist.