A double-blind, randomized, phase 1b, multiple dose trial of 14 days of treatment with POMA (80 mg, 160 mg, 240 mg, 320 mg) in clinical high risk patients to determine which dose, if any, reduces glutamate and metabolism using MRI techniques. The GO NO-GO decision will be whether or not any dose tested in the R61 phase of the trial decreases left hippocampal CA1 region cerebral blood volume (CBV).