At ECNP 2022, Professor Roger McIntyre discussed how major depressive disorder (MDD) can be impacted by prior trauma, especially when experienced in early life. Trauma increases the likelihood and severity of MDD and is associated with the occurrence of co-morbid conditions such as post-traumatic stress disorder and obesity. Anhedonia and emotional blunting are also more likely to be symptoms of MDD in people who have experienced prior trauma. Such patients may also have persistent alterations in their inflammatory and stress systems and are less likely to respond to some antidepressant medications.