A "healthy" mind in a dysfunctional environment can produce physical symptoms that mimic mental illness---anxiety for example---which makes diagnosis difficult, and is the root of the difference between the blues and clinical depression.
Im not sure I understand. When you say "mimic mental illness", are you saying that environmental factors cannot cause a "healthy" mind to get a "real" mental illness?
But to my mind, no. The problems of a healthy mind in an unhealthy environment are easy to solve: change the environment and the problem goes away. On the other hand, problems such as my depression get only temporary relief from changing the environment; the only long term relief has been drug treatment.