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Can PTSD Overlap with Depression?

In this article, we'll explain what depression is and how it can affect the effectiveness of treatments for PTSD.
A person sitting alone on the waterfront.
© University of Glasgow
Before considering how PTSD can overlap with other mental disorders, it might be useful to visit this article, Defining PTSD, for a refresher on the core symptoms of the disorder.

What is Depression?

Depression is one of the mental disorders most commonly associated with exposure to trauma. It is quite common for people to go through short periods during which they feel ‘depressed’, which is a state of mind characterised by unhappiness, lack of motivation and hopelessness. Often, these periods of low mood occur after a negative experience such as failing an exam or not being successful at a job application. However, in the large majority of cases, these feelings are short-lived, and the individuals will return to their normal state of mind and wellbeing.
Man sitting on a concrete bench.Man sitting on a concrete bench. Source: Pexels.com

Clinical Depression

Clinical depression is different from these natural periods of low mood and ‘depression’ in that it does not always have an identifiable cause, is much more long-lasting or pervasive, and it has an impact on an individual’s ability to go about their daily life.
Clinical depression is known as Major Depressive Disorder (MDD) in the DSM-5. The main symptoms of clinical depression are outlined below:
  • Depressed mood
  • Anhedonia – loss of interest or pleasure in all or most activities
  • Anergia – lack of energy
  • Sleep disturbances
  • Weight and appetite changes
  • Poor concentration and memory
  • Negative thoughts and cognitions which may lead to feelings of worthlessness
  • Suicidal thoughts or suicide attempts
These symptoms must be sufficiently severe to cause an individual severe distress or impairment in completing tasks associated with their daily life, including at home and at work.

Depression and PTSD

Following exposure to trauma, depression and PTSD frequently co-occur and are often not easily distinguishable, especially in the first few months following the traumatic experience (O’Donnell et al., 2004). Some evidence has suggested that approximately 50% of those diagnosed with PTSD also meet the criteria for MDD (Flory & Yehuda, 2015). The relationship between these disorders is not fully understood. The current evidence base suggests that PTSD may be a causal risk factor for the development of MDD (Frías et al., 2016). However, this relationship is likely to be bi-directional, meaning that pre-existing MDD may increase the risk of developing PTSD following exposure to trauma. There is also a suggestion that PTSD and MDD share common risk factors and vulnerabilities, meaning that if an individual possesses risk factors that predispose them to MDD, they would also be predisposed to PTSD. Frias and colleagues also reported that PTSD symptomatology is more severe in individuals with comorbid PTSD and MDD than in individuals with PTSD alone.
A person talking to a therapist on a couch.A person talking to a therapist on a couch. Source: Pexels.com

Treatment Implications

Flory and Yehuda (2015) highlighted that the overlap between MDD and PTSD may have significant implications for treatment. Frías and colleagues (2016) outlined how comorbid MDD can affect the effectiveness of treatments for PTSD. The results of the review are summarised in the table below.
PTSD Treatment Impact of Comorbid MDD on Treatment Effectiveness
Cognitive Processing Therapy (CPT) Many studies with small sample sizes have found that the presence of comorbid MDD does not impact on the effectiveness of Cognitive Processing Therapy for treating PTSD symptoms (Lloyd et al., 2014; Walter, et al., 2012). However, two larger randomised controlled trials (RCT) had conflicting results: one suggested that presence of comorbid MDD lowered therapeutic response to Cognitive Processing Therapy in individuals with PTSD (Stein et al., 2012), while the other found that higher depression severity was associated with increased effectiveness of Cognitive Processing Therapy in individuals with PTSD (Rizvi et al., 2009).
Prolonged Exposure Therapy (PET) Research into the effectiveness of PET has produced inconsistent results. One RCT found that higher levels of depression was associated with decreased therapeutic effectiveness of PET (Stein et al, 2012), while another RCT found the opposite result (Rizvi et al., 2009). Other studies (Hagenaars et al., 2010; van Minnen et al., 2002) have also found that depression severity does not influence therapeutic effectiveness of PET when treating PTSD.
Cognitive-Behavioural Therapy (CBT) Research has yielded inconclusive findings about the use of CBT for patients with such comorbidity. Two studies have found that higher baseline depression was positively associated with improvement in PTSD symptoms (Forbes et al., 2003; Taylor et al., 2001). However, other studies (Deblinger et al., 2006; Richardson et al., 2011) have found that depression severity does not predict the therapeutic effectiveness of CBT for the treatment of PTSD.
Anti-depressants The literature has produced mixed results in relation to anti-depressant use in this population. In one RCT, veterans who had PTSD and experienced higher levels of depressive symptoms responded less positively to amitriptyline (Davidson et al., 1993). Another RCT found that comorbid MDD did not influence the effectiveness of sertraline in a sample of trauma-affected individuals (Brady & Clary, 2003).

4.8

57 Reviews
As demonstrated, research examining whether the presence of comorbid MDD can influence the effectiveness of therapies aimed at treating PTSD has produced mixed results. Further research is needed in this area of study in order to better understand the implications of comorbid MDD for the treatment of PTSD.
References
Brady, K. T., & Clary, C. M. (2003). Affective and anxiety comorbidity in post-traumatic stress disorder treatment trials of sertraline. Comprehensive Psychiatry, 44(5), 360–369. doi:10.1016/S0010-440X(03)00111-1
Davidson, J. R., Kudler, H. S., Saunders, W. B., Erickson, L., Smith, R. D., Stein, R. M., Lipper, S., Hammett, E. B., Mahorney, S. L., & Cavenar Jr., J. O. (1993). Predicting response to amitriptyline in posttraumatic stress disorder. American Journal of Psychiatry, 150(7), 1024–1029. doi:10.1176/ajp.150.7.1024
Deblinger, E., Mannarino, A. P., Cohen, J. A., & Steer, R. A. (2006). A follow-up study of a multisite, randomized, controlled trial for children with sexual abuse-related PTSD symptoms. Journal of the American Academy of Child and Adolescent Psychiatry, 45(12), 1474-1484. doi:10.1097/01.chi.0000240839.56114.bb
Elhai, J. D., Contractor, A. A., Tamburrino, M., Fine, T. H., Cohen, G., Shirley, E., Galea, S. (2015). Structural relations between DSM-5 PTSD and major depression symptoms in military soldiers. Journal of Affective Disorders, 175, 373-378. doi:10.1016/j.jad.2015.01.034
Flory, J. D., & Yehuda, R. (2015). Comorbidity between post-traumatic stress disorder and major depressive disorder: Alternative explanations and treatment considerations. Dialogues in Clinical Neuroscience, 17(2), 141-150. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4518698/
Forbes, D., Creamer, M., Hawthorne, G., Allen, N., & McHugh, T. (2003). Comorbidity as a predictor of symptom change after treatment in combat-related posttraumatic stress disorder. Journal of Nervous and Mental Disease, 191(2), 93–99. doi:10.1097/01.NMD.0000051903.60517.98
Frías, Á., Martínez, B., Palma, C., & Farriols, N. (2016). Clinical impact of comorbid major depression in subjects with posttraumatic stress disorder: A review of the literature. Nordic Psychology, 68(4), 257-271. doi:10.1080/19012276.2016.1162106
Hagenaars, M. A., van Minnen, A., & Hoogduin, K. A. L. (2010). The impact of dissociation and depression on the efficacy of prolonged exposure treatment for PTSD. Behaviour Research and Therapy, 48(1), 19-27. doi:10.1016/j.brat.2009.09.001
Lloyd, D., Nixon, R. D., Varker, T., Elliott, P., Perry, D., Bryant, R. A., Creamer, M., & Forbes, D. (2014). Comorbidity in the prediction of cognitive processing therapy treatment outcomes for combat-related posttraumatic stress disorder. Journal of Anxiety Disorders, 28(2), 237–240. doi:10.1016/j.janxdis.2013.12.002
O’Donnell, M. L., Creamer, M., & Pattison, P. (2004). Posttraumatic stress disorder and depression following trauma: Understanding comorbidity. American Journal of Psychiatry, 161(8), 1390-1396. https://doi.org/10.1176/appi.ajp.161.8.1390
Richardson, J. D., Elhai, J. D., & Sarreen, J. (2011). Predictors of treatment response in canadian combat and peacekeeping veterans with military-related posttraumatic stress disorder. The Journal of Nervous and Mental Disease, 199(9), 639-645. doi:10.1097/NMD.0b013e318229ce7b
Rizvi, S. L., Vogt, D. S., & Resick, P. A. (2009). Cognitive and affective predictors of treatment outcome in cognitive processing therapy and prolonged exposure for posttraumatic stress disorder. Behaviour Research and Therapy, 47(9), 737–743. https://doi.org/10.1016/j.brat.2009.06.003
Stein, N. R., Dickstein, B. D., Schuster, J., Litz, B. T., & Resick, P. A. (2012). Trajectories of response to treatment for posttraumatic stress disorder. Behavior Therapy, 43(4), 790–800. doi:10.1016/j.beth.2012.04.003
Stein, D. J., McLaughlin, K. A., Koenen, K. C., Atwoli, L., Friedman, M. J., Hill, E. D., Kessler, R. C. (2014). DSM-5 and ICD-11 definitions of posttraumatic stress disorder: Investigating “narrow” and “broad” approaches. Depression and Anxiety, 31(6), 494-505. https://doi.org/10.1002/da.22279
Taylor, S., Fedoroff, I. C., Koch, W. J., Thordarson, D. S., Fecteau, G., & Nicki, R. M. (2001). Posttraumatic stress disorder arising after road traffic collisions: Patterns of response to cognitive-behavior therapy. Journal of Consulting and Clinical Psychology, 69(3), 541–551. doi:10.1037/0022-006X.69.3.541
van Minnen, A., Arntz, A., & Keijsers, G. P. J. (2002). Prolonged exposure in patients with chronic PTSD: Predictors of treatment outcome and dropout. Behaviour Research and Therapy, 40(4), 439-457. doi:10.1016/s0005-7967(01)00024-9
Walter, K. H., Barnes, S. M., & Chard, K. M. (2012). The influence of comorbid MDD on outcome after residential treatment for veterans with PTSD and a history of TBI. Journal of Traumatic Stress, 25(4), 426–432. doi:10.1002/jts.v25.4
© University of Glasgow
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Post-Traumatic Stress Disorder (PTSD) in the Global Context

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