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2. Differential Diagnosis of PTSD: The Importance of Comorbidities
David N. Osser, MD,
Associate Professor of Psychiatry
Harvard Medical School
Brockton Division of the VA Boston Healthcare System

3. Specific comorbidities
Substance Use Disorder
Major Depression
Bipolar Disorder
Psychosis
Impulse Control Disorder

4. Substance use disorders and PTSD
Common
Increased risk of abusing prescription medications
Chilcoat HD, Breslau N. Posttraumatic stress disorder and drug disorders: testing causal pathways. Arch Gen Psychiatry 1998;55:913–7.

5. Substance use disorders and PTSD
Recommendations
Screen for SUD
Avoid benzodiazepines

6. Substance use disorders and PTSD
Recommendations
Screen for SUD
Avoid benzodiazepines

7. Substance use disorders and PTSD
Algorithm reccomendations don’t apply:
If the patient is actively abusing substances
Osser DN, Renner JA, Bayog R. Algorithms for the pharmacotherapy of anxiety disorders in patients with chemical abuse and dependence. Psychiatr Ann 1999;29:285–301.

8. Substance use disorders and PTSD
Specific medications
Desipramine
One positive study with this comorbidity (no effect otherwise)
Topiramate 300 mg/day
Small study of PTSD patients with alcohol use disorder
Mason BJ, Kocsis JH, Ritvo EC, Cutler RB. A double-blind, placebo-controlled trial of desipramine for primary alcohol dependence stratified on the presence or absence of major depression. JAMA 1996;275:761–7

9. Substance use disorders and PTSD
Specific medications
Desipramine
One positive study with this comorbidity (no effect otherwise)
Topiramate 300 mg/day
Small study of PTSD patients with alcohol use disorder
Batki, SL., et al. Topiramate treatment of alcohol use disorder in veterans with posttraumatic stress disorder: a randomized controlled pilot trial." Alcoholism: Clinical and Experimental Research 38.8 (2014):

10. Major depression and PTSD
Increases the risk of developing PTSD
Major depression
You may want to know that patients with both diagnoses may not respond to antidepressants as well as those PTSD alone.
Breslau N, Davis GC, Peterson EL, Schultz LR. A second look at comorbidity in victims of trauma: the posttraumatic stress disorder-major depression connection. Biol Psychiatry 2000;48:902–9.

11. Major depression and PTSD
Increases the risk of developing PTSD
Major depression
Less responsive to antidepressants
Patients with: depression + PTSD
You may want to know that patients with both diagnoses may not respond to antidepressants as well as those PTSD alone.
Brady KT, Clary CM. Affective and anxiety comorbidity in post-traumatic stress disorder treatment trials of sertraline. Compr Psychiatry 2003;44:360–9

12. Bipolar disorder and PTSD
We recommend screening for bipolar disorder in PTSD patients
Be very cautious about using antidepressant
Consider skipping to other options

13. Bipolar disorder and PTSD
We recommend screening for bipolar disorder in PTSD patients
Be very cautious about using antidepressant
Consider skipping to other options

14. Psychosis (e.g. schizophrenia)
Psychosis and PTSD
Psychosis (e.g. schizophrenia)
PTSD symptoms

15. Psychosis and PTSD Psychosis PTSD
Consider skipping initial sleep management
Go straight to antidepressants followed by augmentation with antipsychotics
Psychosis
PTSD
Kozaric-Kovacic D, Pivac N. Quetiapine treatment in an
open trial in combat-related post-traumatic stress disorder with psychotic features. Int J Neuropsychopharmacol
2007;10:253–61.

16. Special considerations in pregnancy
Women of childbearing potential
Avoid paroxetine
Risk of fetal septal defects
Fluoxetine may have comparable risks
If the patient is a woman of childbearing potential, avoid paroxetine due to the risk of fetal septal defects.
A study published in 2015 by Reefhuis and colleagues also raises concerns about the use of fluoxetine, as it may have comparable risks to paroxetine.
Reefhuis, J., Devine, O., Friedman, J. M., Louik, C., & Honein, M. A. (2015). Specific SSRIs and birth defects: bayesian analysis to interpret new data in the context of previous reports.