The line between stress and a mental disorder is much like the one that exists between neurosis and psychosis. Just as we all experience some form of neurotic behavior from time to time, we all experience stress as well. And while neurosis does not always result in psychosis, left untreated, it can lead to a break with reality. Similarly, while many of us will successfully cope with the nerve-racking and demanding events of our lives, for some the effects of stress will compound as each new scenario is layered upon a previously unsuccessful attempt at coping. Over time, the negative effects of poor coping mechanisms as well as insufficient recovery time between critical events will result in some form of mental illness.
Stress and eustress
In order to better understand the impact of stress on mental health, we must first be able to conceptualize "stress." Stress comes in two forms, negative and positive. While we tend to be more familiar with the kind of stress that results from painful situations or crisis, stress can be experienced even in the midst of excitement and anticipation. A skydiver may experience the effects of stress even while he enjoys the sport of skydiving. We call this kind of stressful response to a positive pursuit, "eustress."
Role of cortisol and adrenaline
When an individual experiences stress, whether positive or negative, his brain produces two chemicals, cortisol and adrenaline, to help him cope with a greater demand for high energy and the kind of quick thinking that characterizes living on the edge. When stress-producing events occur one after the other, the effects of pressure and tension are continuous. The brain maintains constant production of cortisol and adrenaline to meet the perceived demands of relentless stress. When an overabundance of cortisol and/or adrenaline collects in the body, a toxic reaction occurs. Excessive amounts of these chemicals can cause feelings of unexplained jitteriness, unusual levels of hyperactivity, somatic complaints like headaches, muscle aches, and even hearth arrhythmia's. Essentially, the brain keeps telling the body that it must continue to perform as if in a state of hyper alertness.
At toxic levels, cortisol and adrenaline contribute to a sustained feeling of being stressed. When an individual lives with a chronic perception or sensation of stress, he becomes more susceptible to mental disorders. Anxiety disorders such as generalized anxiety and phobic forms of anxiety or mood disorders like depression are common mental health issues that can occur as a result of a chronic state of stress.
Genetics and environment
In the bigger picture, stress is also impacted by genetics and environment. Consequently, an individual who has a familial history of depression and who has been physically abused may also be at risk for more a severe mental illness such as Acute Stress Disorder, Post Traumatic Stress Disorder and even Dissociative Identity Disorder.
Does everyone who experiences stress develop a mental disorder? No, of course not. However, when an individual is incapable of dealing with stress and/or experiences multiple stressful events from which he finds himself incapable of recovery, he may be at risk of developing a mental illness.
So, what's the answer? Really, it's not one but two answers. In order for an individual to forestall the possibility of a negative mental health outcome from the effects of stress, he must first develop a positive set of coping mechanisms to offset the effects of stress in his life. Ultimately though, he will need to learn to live a balanced life; one that is characterized by not just stress, or even eustress, but periods of tranquility and contentment and a fresh appreciation for the understated things in life.