Medication Titration Schedule: The target atomoxetine dose for this study is 80 mg/day. The following titration schedule will be used: Week 1-2: atomoxetine 40 mg/day; Week 3-8: atomoxetine 80 mg/day. This titration schedule serves to enhance tolerability and minimize side effects. Participants randomized to placebo will receive an equal number of placebo tablets during the titration schedule.