Views on vulnerability Cognitive and neurobiological vulnerability during remission of Major Depressive Disorder

Major Depressive Disorder (MDD) is a prevalent and highly disabling psychiatric disorder. About 50% of patients that suffer from MDD will experience at least one other depressive episode in their lifetime. Further, the risk of becoming depressed again rises after each experienced depressive episode. This high recurrence rate is one of the reasons that MDD is very debilitating and that it is associated with exceedingly high social and economic costs. Therefore, there is a great need to better understand neurobiological and cognitive vulnerability factors in individuals remitted from recurrent MDD. This is an important step in discovering factors that might ultimately aid the identification of markers for recurrence risk; and help to develop or alter preventative interventions for recurrence in MDD patients.
This thesis examined vulnerability for recurrence in patients remitted from Major Depressive Disorder (MDD) from a cognitive perspective (e.g. negative thoughts and psychological reactions to sadness/stress) and a neurobiological perspective (e.g. communication within and between different networks of areas in the brain). On a cognitive level, we found that dysfunctional thought processes in response to sadness or stress, captured by cognitive reactivity and rumination, are important vulnerability factors for recurrent MDD. On a neurobiological level we provide evidence that the Default Mode Network, Salience Network, Frontal Network and striatum might all play important roles in neural vulnerability when patients are in remission of MDD. Alterations in these networks, and the interplay between them, might reflect difficulty to disengage from negative self-referential information in remitted patients.