PTSD

PTSD Is Post Traumatic Stress Disorder, it's an actual disease or illness that affects the victim of this disorder mentally, physically, and emotionally. It is classified under Anxiety Disorders, though Anxiety is most definitely not all it comes with. The people with this disorder live daily differently then us, trying to avoid thoughts and feelings of the trauma that had once caused their suffering now. They tend to avoid place, people, or things that remind them of any of their traumatic experiences, and they are sensitive to things that to other people are normal but to them are treacherous. 
The symptoms of a sufferer include:
substance abuse ( to help take their mind off of the trauma)
a smaller hippocampus
have trouble keeping their realitionships
loneliness
panic- anxiety
emotional problems mostly in general,
sleep deprivation, etc.
The causes of PTSD are :
Any type of trauma
usually life-threatening, or witnessing a severe accident or severe "torture" to another human, being the victim of torture or kidnapping, sexual assaults, rape, murder, exposure to war combat, forms of abuse, etc.


Memory and Emotion greatly relate to PTSD, it is the cause of PTSD. If you wouldn't have had the memory of this traumatic experience then you would not think or care about it. If you didn't have emotion, the memory would mean nothing to you, you wouldn't dwell on it. It would fade away with time, and soon you would forget it ever happened.