Although trauma is relatively common, PTSD is less common. In general, lack of a temporal relationship between the trauma and the onset or exacerbation of symptoms, as well as the presence of symptoms that are not included in the diagnostic criteria for PTSD, suggest a disorder other than PTSD.
People with PTSD may present in the course of seeking treatment for another psychiatric illness. Up to 80 percent of people with the disorder have an additional psychiatric disorder, which may be the primary complaint or which may emerge upon taking the patient’s history (Lange et al., 2000). The most common comorbidities are mood and anxiety, substance use and dissociative disorders.
The following section lists disorders that may be confused with PTSD and describes how they differ.
- Involve a stressor, such as job loss, that does not meet Criterion A for PTSD in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5; APA, 2013)
- May meet any or all other PTSD criteria
Acute Stress Disorder
- Lasts less than one month
- May or may not develop into PTSD
Major Depressive Disorder
- May include DSM-5 Criterion D and E symptoms (low mood, social withdrawal, distorted negative cognitions)
- Current episode may be precipitated by Criterion A trauma
- Insufficient Criterion B and C symptoms (intrusion and avoidance) to meet full criteria for PTSD
- Slower mood changes, not linked to traumatic stimuli (Lanius et al., 2016)
- Decreased need for sleep (compared with insomnia or sleep disruption in PTSD)
Anxiety Disorders and Obsessive-Compulsive Disorder
- Anxiety content not associated with a specific traumatic event
- Perceptual disturbances not a direct re-experiencing of past trauma
- Greater impairment in reality testing and interpersonal relatedness (Lanius et al., 2016)
- Hearing child voices most likely indicates dissociation rather than psychosis (Dorahy et al., 2009)
Cluster B Personality Disorders
- Prominent emptiness and anger, compared with fear, shame and depression in PTSD (Lanius et al., 2016)
- Onset prior to traumatic event (APA, 2013)