In the nineties, and and up to about ten years ago, I would hear Doctors mention &quot;chemical imbalance&quot;.<p>Today, I couldn&#x27;t imagine a medical doctor claiming a person&#x2F;patient has a chemical imbalance.  The truth is they just don&#x27;t know what causes mental illness, and most mental disabilities.<p>For awhile, it looked like they could increase dopamine, decrease serotonin, blah, blah, etc. and they were finally getting a handle on these complicated psychological problems.<p>Well, they were wrong with their chemical imbalance theories, and they are back to speculation--wild speculation in most cases.  Out of all the medical specialties, Psychiarty has not made much progress from the 50&#x27;s.  At least they aren&#x27;t carring around ice picks and severing the frontal lobes though.