A recent study in Australia studied the use of treating people diagnosed with Post Traumatic Stress Disorder with Substance or Alcohol Dependence, (http://dxdoi.org/10.1891/1933-3126.96.36.199). For those unfamiliar, it is extremely common for those with PTSD to have alcohol or substance use disorders. Recent prevalence rates are quite varied. However, one of those studies (Kessler, Sonnega, Bromet, Hughes and Nelson, 1995) found that women with PTSD were more than four times as likely to have a substance use disorder and 2.5 times as likely to have an alcohol use disorder. For men, the statistics are roughly the same as for women with regards to alcohol (more than twice as likely) and with drug abuse it was actually less at 3 times as likely.
Many theories have been proposed as to what the high rates of comorbidity suggest and there are also discussions as to what came first, the drug and alcohol use or the PTSD. The results of this study would indicate that the theory of self-medication has validity and is worthy of further study.
Researchers found that using standard EMDR protocol to process past traumas (none involving use of alcohol or drugs) resulted in greatly reducing substance and alcohol use. After a year, 80% of those studied no longer had symptoms consistent with current alcohol or substance dependence.