From the Expert: Understanding Post-Traumatic Stress Disorder

By: Dr. J. Andrew Chacko, medical director, Addiction Consultation & Treatment Team, Palo Alto VA

Post-Traumatic Stress Disorder or PTSD: the diagnosis seems to be everywhere, thrown around in the vernacular like depression and anxiety. News anchors recount stories of soldiers returning from deployment with it, and impassioned politicians talk about their underserved constituents suffering from it.

As a psychiatrist for the Veterans Health Administration (VHA), I see a great deal of it among my patients young and old, male and female, Black, White, Asian, Latino, and any other decent.

But what is it?

To understand PTSD, we should first understand why we have memory. Memory serves one purpose – to inform our future decisions, by learning from the past. The searing hot pain we felt from touching a hot stove is a vivid reminder not to repeat it. Our brain is smart enough to extrapolate that lesson to other potentially hot objects, so we can safely avoid those too. It is so smart in fact, that it can learn that lesson (thanks to mirror neurons) simply by watching other people suffer. For example, imagine a group of guys that just saw a fellow male getting kicked in the groin.

But it is the emotion we felt, rather than the pain, that determines whether an action was “good” or “bad”. Ideally, favorable choices make you feel good and therefore worth repeating. Conversely, bad choices make you feel bad. It is nowhere near a perfect system, and it can easily be hijacked. Drugs for example may make people artificially feel really good, which makes them want to keep doing it, even after they realize that it may not be the best decision for them.

By contrast, traumatic experiences carry too strong an emotion for the brain to process and file away as good or bad, the way it does with other memories. One way to conceptualize this is that once “filed” they become memories, but “unfiled”, we continue to feel them as if they were ongoing. This is called re-experiencing, and can be a flashback, or a nightmare. Different cues in the environment, like crowds, or a loud noise may even bring those experiences instantly to the surface. Those are called triggers. Staying away from painful triggers is called avoidance – and is another hallmark of PTSD.

The great news is that it is treatable. Your local VHA office is a great resource to help veterans cope with PTSD.

To my brothers and sisters who served, and those who take care of those who did – THANK YOU!

Happy Veterans Day!


For more information and resources for veterans mental health click here.


Dr ChackoDr. J. Andrew Chacko is the Medical Director of the Addiction Consultation & Treatment Team for the Palo Alto VA, and a private practice psychiatrist in San Francisco.

He completed his training at Tripler Army Medical Center, the only civilian selected for a military psychiatry residency, gaining special expertise in PTSD and TBI.

He earned his MD from Tufts University School of Medicine. He is a graduate of the U. S. Naval Academy, and served 12 years in the Navy before he completed his post-baccalaureate studies through Harvard, and earned his graduate degree in Mechanical Engineering (Product Design) at Stanford University. You can learn more at