A pilot study was completed in both rhesus and squirrel monkeys to determine the efficacy of the DSP-4 injection. Thirty days following injection, monkeys were euthanized and brain sections were analyzed for noradrenergic depletion. In the regions of interest, there was 60-75% depletion confirming the effectiveness of the DSP-4. A longitudinal study was completed in both squirrel and rhesus monkeys. Monkeys received an initial dose followed by a booster dose at 3 and 6 months and then were terminated at 9 months. Rhesus monkeys were also behavior tested on a task of learning and memory. Quantification of the noradrenergic depletion in the tissue samples is underway in both monkey species.