The process of rumination activates additional regions of the brain in adolescents recovering from major depressive disorder compared to healthy adolescents, according to a study recently published in Cognitive Affective and Behavioural Neuroscience.
Adolescents diagnosed with major depressive disorder (MDD) suffer with many distressing outcomes including increased risk of suicide, increased likelihood of being hospitalized and abnormal social functioning in areas such as school, work and family relationships. Adolescents with a history of MDD have a 40% chance of relapse within 2 years. It is therefore important to identify common risk factors associated with adolescents in remission from MDD to improve our understanding of the mechanisms underlying relapse.
Rumination is a persistent pattern of negative thinking characterized by continued reflective and uncontrollable emotion. Previously, research has suggested that rumination is associated with increased severity of depressive symptoms in adults and also plays an important role in MDD relapse. However, little research has been carried out that investigates the effect of rumination on adolescents in remission from MDD, which is surprising because this is a sub-population of people particularly vulnerable to relapse.
The study, conducted by researchers from the University of Illinois at Chicago and the University of Exeter, UK used functional magnetic resonance imaging (fMRI) to examine the neural mechanisms behind rumination in adolescents in remission from MDD (rMDD). 26 rMDD adolescents and 15 healthy participants completed a task that induced rumination, as well as a distraction task whilst undergoing MRI.
The results showed that during the rumination task all participants engaged regions in the default mode network, which is an area of highly interactive brain regions including the posterior cingulate cortex, medial prefrontal cortex, inferior parietal lobe and medial temporal gyrus. Activation of these areas during rumination was linked to self-reported rumination and depressive symptoms in all participants. However, rMDD adolescents displayed greater activation in visual, sensory and emotion processing brain regions compared to healthy controls.
Overall, the study suggests that increased activation of visual, sensory and emotion processing regions is an important difference between rumination in rMDD adolescents and healthy controls. Activation of these areas during the rumination task was associated with an increase depressive symptoms, suggesting that recruitment of such areas in rumination could be a risk factor for relapse in adolescents with MDD.