As more adults seek treatment for depression and other psychiatric issues, companies often do not have policies or procedures in place to support them. While companies support employee health initiatives, there is rarely a culture that encourages people to share health issues. Law requires companies to make provisions for employees with disabilities, which could include flexible working hours or reassigning workers. Some companies offer training to allow employees to spot others who may have mental illnesses, but say they don't want it to go too far. There is also a stigma attached to mental illness and many employees are wary of discrimination from companies and coworkers.
See "Managing Mental Health at Work", Melissa Korn, The Wall Street Journal, August 28, 2012