Can PTSD Overlap with Depression?

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. 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. 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.

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

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^{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}

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