Post Traumatic Stress Disorder is typically categorized as an anxiety disorder, but the symptoms also include any form of depression disorder as well. The relationship between anxiety, depression, and PTSD is so strong that many people are misdiagnosed with any form of anxiety or any form of depression disorders. It is also interesting to note that many people are diagnosed, or misdiagnosed with personality disorders as opposed to PTSD. This is probably because anxiety makes you high strung and depression makes you slow down. The two are at odds with one another.
I believe that Post Traumatic Stress Disorder is more of a stress disorder and is the umbrella disorder that encompasses depression and anxiety. If you have PTSD, you naturally have all of the symptoms of both depression and anxiety disorders in addition to other symptoms. In fact, the other symptoms of PTSD can produce anxiety and depression, which makes it all a big revolving door.
For example, someone who suffers from PTSD can experience a trigger about their experience. Any sight, smell, sound, or thought that is related to trauma can trigger a particular feeling or memory. These can very shocking and upsetting to the person, which, in addition to other reactions like anger and rage, causes an abundance of stress. Stress, in turn leads to the hyper vigilant and hyper aroused response, which can produce physical symptoms like hyperventilation or heart palpitations. When a certain stress threshold has been reached in someone who has PTSD, the person is hyperventilating, their heart is going 90 miles and hour, this is called anxiety and the person is apt to experience panic attacks.
Anxiety inevitably translates into depression in someone who has PTSD. When stress levels are high and the person is on overload, their nervous system will disengage by causing the person to become very spacey. This is called dissociation, or disengaging and it is a physical symptom as well as an emotional one. As the person dissociates, they do tend to calm down, however, depression is never very far behind. As the limbic system, the brain, and the body relaxes, so does the hyper vigilant response and the surge of hormones that engage the fight or flight response. Mentally, it's like letting the air out of a balloon. Can you see how this is a revolving cycle in someone who has this disorder?
It's no wonder that so many people are diagnosed with multiple conditions, put on multiple medications that counteract one another, and are treated for the wrong conditions. PTSD is an anxiety disorder and a depression disorder. It is a unique condition that presents equal and opposite symptoms. The constant oscillation between depression and anxiety is exhausting and makes no sense to people that do not understand this disorder. The good news is that once you learn how to relate one symptom to another in a way that makes logical sense to you, you are in a better position to minimize these up and downs and regain your equilibrium.