While PTSD may not be visible externally, there are real physical changes that occur within the brain. After a traumatic event your brain is literally rewired to help it cope and try to prevent a similar instance from occurring. Everything becomes a threat and you become hypersensitive to new, potential threats. Your short term memory may be affected indefinitely. The blood flow in your brain can change decreasing your ability for language and memory and increasing feelings of sorrow and anger.
All too often people turn to drugs and alcohol to try and minimize the side effects of this rewiring of the brain. It is important to seek help or encourage others to do so in order to learn healthy coping skills.
Follow this link for information on how to find help