Specific hypotheses to be tested include: 1) that significant improvement in Clinical Global Impression - Improvement -SMD (CGI-I-SMD) scores and other secondary measures are evident after open-label LDX titration; 2) that participants randomized to fluoxetine will demonstrate additional significant improvement in CGI-I-SMD scores and other secondary measures in comparison to participants randomized to placebo; 3) that combination LDX and SSRI therapy is safe and well tolerated, and 4) that EEG profiles will normalize with treatment.