Many servicemen/women were given the anti-malarial drug Mefloquine(Lariam) before being deployed to Iraq and Afghanistan. The side effects include paranoia, psychosis and aggression,among others. The symptoms closely mimic PTSD and Traumatic Brain Injury. The VA has advised its doctors to monitor veterans for symptoms. This drug is felt to be connected to several murders committed by returning veterans. British research showed symptoms can occur in as many as 1 out of 140. Symptoms can be manifested long after the medication had been discontinued. 
 Given that the government had denied the effects of Agent Orange and did not recognize PTSD as a legitimate
illness for about twenty years after the war in Vietnam ended they do lack some credibility. Check it out, Lariam.