the drop in estrogen levels during premenopausal can cause hot flashes
, night sweats, weight gain, headaches, vaginal dryness, breast tenderness, and sleep issues. Emotional changes like anxiety, irritability, depression, etc all are encountered. These can be eased with patience, calcium and vitamin D supplements, Zoloft and Prozac for the anxiety and emotional disturbances. If these conditions are ruled out, consider multiple sclerosis and fibromyalgia as the cause for this brain fog.