One of the most invidious aspects of physician depression is the reluctance of physicians to seek help because of a very real perception that to do so might place them at risk for intrusive examinations and actions by their licensing authority, ostensibly to determine "fitness for practice" and thereby protect the public.  

However, studies suggest that the physician's clinical practice is the LAST life area affected by depression, so integral is the practice of medicine to a physician's sense of self worth and reason for continuing to function in the world.  Therefore, a physician whose low level depression does not in any way impact his or her practice, may defer or bypass potentially life saving intervention for fear of loss of livelihood through exposure to punitive authorities.

Here are reports from the literature about this phenomenon, and a small survey I conducted of emergency physicians which illustrates how pervasive the belief that: to seek help will greatly compound the problem, rather than helping to deal with it. 

This article on Physician Suicide describes the phenomenon in context.

This article attempts to explain the relationship between medical licensure boards and physician health or diversion programs (see also PHPs)

Steven Miles is an acclaimed medical ethicist and physician who has successfully faced licensure challenge based on treatment for Bipolar Illness in MN.  His story is here. 

Silent Treatment: Suicide and Depression in Emergency Physicians, Andrew L, EPMonthly December 2005

Survey on EP depression and suicide, EPMonthly December 2005

Readers Respond to Silent Treatment, Andrew L EPMonthly March 2006

Physician Suicide: Risk Factors and Prevention, Kaufman, I.M. Ontario Medical Review Sept 2000 20-22

Encouraging Treatment in Depressed Medical Professionals Physicians' Weekly Sept 2005

Legal Aspects of Mental Health reporting to licensure boards by physicians can be explored in this article from Journal of Law and Health Policy (1994).

Polfliet SJ published a National Analysis of Medical Licensure Applications in 2008 concluding that many likely violated the ADA

A 2009 survey in Academic Medicine suggests that 69% of state medical license applications contain questions that are or are likely to be impermissible under the Americans with Disability Act.  AMA also has policy relating to this issue.

Licensing and Physician Mental Health: Recommendations. Suicide Prevention International online article.

Hendin, et al. Licensing and Physician Mental Health: Problems and Possibilities from the Journal of Medical Licensure and Discipline 93:2 (2007) is an important study of policies of medical boards which may result in physician reluctance to seek help.

The References section contains more articles relating to this issue.