Lamictal interferes significantly with my memory. This drug inhibits the dihydrofolate reductase enzyme, and this enzyme is the first step in a series of enzymes that convert biologically inactive folic acid into biologically active levomefolic acid (L-methylfolate).[1] Most fortified foods and supplements use folic acid. My working hypothesis is that the body can't produce an adequate supply of L-methylfolate, and this in turn reduces methionine production from homocysteine in the brain (methylfolate passes through the blood brain barrier). Methionine is a methyl donor, and methylation is important in the epigenetics of memory. I've also read that high levels of homocysteine can cause memory impairment. It could also be that we suffer from a defective MTHFR polymorphism and lamictal exacerbates the problem.

In theory, if you take supplemental L-methylfolate this might fix the problem. I just pieced this hypothesis together the other day and ordered some levomefolate calcium (Metafolin / Deplin) from amazon.com to test it, but I'm still waiting for it to be delivered. I should know pretty quick if it's going to work, I'll let you know how it works out in a week or so.