Major Depressive Disorder and PTSD: Why They Often Happen Together

If you’ve felt stuck in deep sadness after a trauma, you’re not imagining things. Major Depressive Disorder (MDD) and Post-Traumatic Stress Disorder (PTSD) often show up together. This month we looked at how these two conditions connect, what that means for symptoms and treatment, and what you can do right now if this sounds like you or someone you care about.

How MDD and PTSD overlap

PTSD starts after a traumatic event and brings flashbacks, hypervigilance, and avoidance. MDD brings persistent low mood, lack of interest, changes in sleep and appetite, and feelings of worthlessness. Some symptoms clearly overlap — trouble sleeping, trouble concentrating, and numbness or detachment. Research often finds roughly 40–50% of people with PTSD also meet criteria for MDD, so overlap isn’t rare.

Why the overlap? Trauma can change the brain’s stress systems and the way emotions are processed. That same change can make deep sadness more likely. Also, dealing with persistent fear, isolation, or loss after trauma can lead to hopelessness and the low energy typical of depression. Physical effects of chronic stress — like inflammation and disrupted sleep — can make both disorders worse.

What this means for diagnosis and treatment

When both conditions are present, treatment needs to address trauma and mood. Clinicians often use screening tools for PTSD and depression together so nothing gets missed. Effective approaches include trauma-focused therapies like Cognitive Processing Therapy (CPT) or Eye Movement Desensitization and Reprocessing (EMDR), plus therapies that target depression such as behavioral activation and CBT. Medications like SSRIs can help with both sets of symptoms for some people.

Combining treatments matters. For example, stabilizing sleep and routine can make trauma work in therapy more effective. A therapist who understands trauma and mood disorders will pace the work so you don’t get overwhelmed.

Practical steps you can take right now: keep a simple routine, prioritize sleep, stay connected with at least one trusted person, and try short grounding exercises when memories or low mood spike. If thoughts of harming yourself come up, reach out to emergency services or a crisis line immediately—don’t face that on your own.

If you suspect you have PTSD, depression, or both, talk to a clinician and ask for a thorough assessment. Treatment can be tailored to both problems and many people see big improvements. You don’t have to sort this out by yourself — getting the right help can change how you feel and how you cope.