When I was put on Lamictal, for the first 4 months I was as you described. I couldn't follow a simple conversation. I had to rely on constant questions and for apologetic "Can you repeat that?" Mood stabilizers can do that. It's very typical. I have a high protein diet along with omega3 with high DHA which is good for the cerebral cortex and also a good multivitamin. My brain found a way to adapt somehow and I can think as clearly as I ever could now. By the way, I am also on Geodon, an atypical antipsychotic which have shown evidence that suggests, like other anti psychotics, shrink gray matter. A low dose is best.