My primary care doctor thinks that my depressed mood may be a sign of male menopause.

Male menopause (or andropause) generally occurs for men between the ages of 40 and 55, though it can begin as early as 35 or as late as 65. It is a multi-dimensional change of life that involves hormonal, physiological, psychological, interpersonal, sexual, social, economic and spiritual changes.
Finding the right kind of help for male menopause isn't easy, as there are few people anywhere in the country who have the kind of training that is needed. I am in the process of gathering together a list of the best practitioners throughout the country and around the world. If you'd like to contact me at Jed@MenAlive.com, I'd be glad to send you a listing of those I am aware of that I feel can be most helpful.