Functional brain imaging studies of youth depression: a systematic review

Abstract

Background: There is growing interest in understanding the neurobiology of major depressive disorder (MDD) in youth, particularly in the context of neuroimaging studies. This systematic review provides a timely comprehensive account of the available functional magnetic resonance imaging (fMRI) literature in youth MDD.

Methods: A literature search was conducted using PubMED, PsycINFO and Science Direct databases, to identify fMRI studies in younger and older youth with MDD, spanning 13-18 and 19-25 years of age, respectively.

Results: Twenty-eight studies focusing on 5 functional imaging domains were identified, namely emotion processing, cognitive control, affective cognition, reward processing and resting-state functional connectivity. Elevated activity in "extended medial network" regions including the anterior cingulate, ventromedial and orbitofrontal cortices, as well as the amygdala was most consistently implicated across these five domains. For the most part, findings in younger adolescents did not differ from those in older youth; however a general comparison of findings in both groups compared to adults indicated differences in the domains of cognitive control and affective cognition.

Conclusions: Youth MDD is characterized by abnormal activations in ventromedial frontal regions, the anterior cingulate and amygdala, which are broadly consistent with the implicated role of medial network regions in the pathophysiology of depression. Future longitudinal studies examining the effects of neurodevelopmental changes and pubertal maturation on brain systems implicated in youth MDD will provide a more comprehensive neurobiological model of youth depression.

Keywords: Functional magnetic resonance imaging (fMRI); Major depressive disorder (MDD); Youth.

Fig. 1

The extended medial prefrontal network of youth MDD. Shown are brain regions most consistently implicated in fMRI studies of adolescent and youth MDD across 5 domains of functioning. The center panel shows the ‘hub’ of the extended medial network, comprising the anterior cingulate (pregenual, mid-cingulate and subgenual cingulate cortices) and posterior cingulate cortices, and ventromedial prefrontal cortex encompassing medial portions of BA 10 and caudal portions of orbitofrontal cortex/BA 11. Left panel: Cortical regions of the extended medial prefrontal network showing dorsolateral prefrontal cortex (top) and the medial and lateral portions of the orbitofrontal cortex (bottom). Right panel: Coronal slices showing subcortical regions including the amygdala (top) and striatum (bottom). The coronal slice of the striatum (MNI coordinate y = 12 mm) shows the dorsal caudate, and the dorsal and ventral divisions of the putamen.