#39 Pondering "Mental Illness"

The horrible events that have unfolded recently have me pondering on the deeper, quieter concepts of human existence, particularly mine own. Without delving into political grandstanding, I will state that I do not believe guns are the issue, but our lack of care for the mentally ill is going to continue to cause untold tragedies until a solution is enacted. I just can't get my head wrapped around the whole Mental Illness issue.

FIGURE 1. Prevalence of current depression among adults aged ≥18 years, by state quartile — Behavioral Risk Factor Surveillance System, United States, 2006

According to the Washington Post, only 5.6% of national health care spending goes towards mental health treatment. I found this map of depression on the CDC website. According to the World Health Organization, mental illness results in more disability in developed countries than any other group of illnesses, including cancer and heart disease. Other published studies report that about 25% of all U.S. adults have a mental illness and that nearly 50% of U.S. adults will develop at least one mental illness during their lifetime.
Here is the link to the Centers for Disease Control website so you can see the statistics for yourself: http://www.cdc.gov/ - type mental illness in the search box.
Here is the Bing dictionary definition:

mental illness

1.

psychiatric disorder: any psychiatric disorder that causes untypical behavior

 

I do not know enough about mental illness to even speculate what defines "normal" or "quirky" or "odd" from "ill." I suppose the line is drawn when a person cannot function in society. For example, they cannot be responsible enough to hold a job. Is that an illness? Or is it laziness? There must be other, additional factors. Can they function in a traditional relationship? In other words, is the 30 year old guy that still lives in Mom's basement ill? Or just very smart (malicious?) at manipulating other people to provide food, shelter, and necessities? Is the player mentally ill for not committing to a traditional relationship or just smart enough to realize that they don't want the responsibility?
I also looked to the SAMHSA website  http://www.samhsa.gov/healthreform/ for information. There were several articles devoted to the Affordable Care Act (known commonly as "Obamacare.) The main topic appears to be rehabilitation for addiction. Of course, someone who suffers from addiction is certainly encouraged to seek treatment and hopefully become a fully functioning citizen.
So, are all addicts considered mentally ill? Obviously it is a very different type of mental illness than that in which someone hallucinates, or becomes unreasonably violent, or seeks attention in inappropriate ways. What if they appear to be totally "normal" but they don't want to wear shoes? Does that mean they are mentally ill? Here is a link to an insurance question about the Affordable Care Act and mental illness: http://www.askforinsurance.com/health-insurance/obama-health-care-reform-and-mental-health-services.html
I took many classes in college that it seems should answer my questions about what, exactly, does "mentally ill" mean? Psychology, Sociology, Anatomy & Physiology, etc...the only conclusion I can come to is that people are expected to behave within certain parameters of society and that there is a fringe element that either chooses to not behave that way or cannot behave that way. They are you and me. They live and work and walk among us. How are we to distinguish who is suffering from depression due to a job loss versus who is going to back to that old job with the intent to cause bodily harm?
I am asking you, my readers, to please help me understand. Post your thoughts and comments.