It is hypothesized that enhancement of GABA neurotransmission during the early course of the illness by tiagabine (Gabitril), a GABA transporter GAT-1-specific inhibitor and a FDA-approved anticonvulsant, will improve both clinical symptoms and working memory in schizophrenia. This improvement is postulated to be the result of tiagabine-mediated modification of the developmental synaptic pruning of prefrontal cortical circuitry. The occurrence of circuitry modification after tiagabine treatment will be assessed by the following independent methodologic approaches: MRI morphometric analysis of prefrontal gray matter volume and fMRI measurements of brain activity patterns during performance of tasks that probe working memory.
