While the symptoms of posttraumatic stress disorder (PTSD) may seem similar to those of other disorders, there are differences. For example, PTSD symptoms may seem similar to those of anxiety disorders, such as acute stress disorder or obsessive-compulsive disorder. However, there are distinct differences between these disorders.

In general, the symptoms of acute stress disorder must occur within four weeks of a traumatic event and come to an end within that four-week time period. If symptoms last longer than one month and follow other patterns common to PTSD, a person’s diagnosis may change from acute stress disorder to PTSD.

While both PTSD and obsessive-compulsive disorder have recurrent, intrusive thoughts as a symptom, the types of thoughts are one way to distinguish these disorders. Thoughts present in obsessive-compulsive disorder do not usually relate to a past traumatic event. With PTSD, the thoughts are invariably connected to a past traumatic event.

PTSD symptoms can also seem similar to adjustment disorder because both are linked with anxiety that develops after exposure to a stressor. With PTSD, this stressor is a traumatic event. With adjustment disorder, the stressor does not have to be severe or outside the “normal” human experience.