Three Miami-Dade residents who played distinct roles in the nation's largest mental-health clinic racket pleaded guilty Wednesday to Medicare-related charges. Joseph Valdes, 30, a marketer for American Therapeutic Corp., and James Edwards, 65, a recruiter for the Miami-based company, pleaded guilty to conspiring to commit healthcare fraud and to paying illegal kickbacks to patients. Adriana Mejia, 40, pleaded guilty to a money-laundering conspiracy. The defendants are the latest to admit their participation in the Medicare scam, which enabled American Therapeutic to bill Medicare $200 million and to net $83 million over eight years, according to the Justice Department. The scheme enabled the seven-clinic company to charge the taxpayer-funded program for psychotherapy that was unnecessary for thousands of patients who faked depression, schizophrenia or bipolar conditions.