This clinical study compares the effectiveness of two anticonvulsants Lamotrigine (Lamictal) Monotherapy and Gabapentin (Neurontin) in patients with treatment resistant affective disorders. We initially have found that the response rate to lamotrigine (51%) exceeded that of gabapentin (28%) or placebo (21%). In this study the placebo phase has been dropped so that we examine possible clinical and biological factors predictors of response. The drugs will be given in a randomized order for six weeks each and you will not know when you are on a given one. There will be a 2-4 week "washout" period between treatments. If you respond well to one of these treatments, a longer open continuation period will be offered at the end of this study. This would involve one or both drugs in combination. A variety of rating scales and brain imaging procedures will also be offered before and during each drug evaluation. Both lamotrigine and gabapentin are generally well tolerated. A serious potentially life threatening rash occurs in about 1/500 patients treated with lamotrigine, however. Common side effects are rash, dizziness, unsteadiness, double vision, blurred vision, nausea, vomiting, insomnia, sedation, and headache. These side effects are usually mild, and resolve with continued time on the drug or a decrease in dosage.