In this Crossover Study, participants were involved for approximately 16 weeks in this sequence: a week of preparing for the initial assessments, baseline measurements (Week 0), 6 weeks on placebo or study drug followed by measurements for effect of drug or placebo (Week 6); a week of titration off of drug, if appropriate (or continued placebo, if on placebo), two weeks of washout, a new baseline assessment (Week 9), six weeks of study drug (or placebo), another set of measurements for effect of drug or placebo (Week 15), and a final titration period to maintain masking of assignment to drug or placebo. Of 17 participants who completed both sequences, data was analyzed for the 15 whose values for all measurement variables were usable.