Effects of 12‐week escitalopram treatment on resting‐state functional connectivity of large‐scale brain networks in major depressive disorder

In this study, the effects of antidepressants on large‐scale brain networks and the neural basis of individual differences in response were explored. A total of 41 patients with major depressive disorder (MDD) and 42 matched healthy controls (HCs) were scanned by resting‐state functional magnetic resonance imaging separately at baseline and after a 12‐week follow‐up. The patients with MDD received escitalopram for 12 weeks. After treatment, patients were classified into those with MDD in remission [MDDr, endpoint 17‐item Hamilton Depression Rating Scale (HAMD) total score ≤7] and those in nonremission (MDDnr). The human Brainnetome Atlas was used to define large‐scale networks and compute within‐ and between‐network resting‐state functional connectivity (rsFC). Results showed the decreased subcortical network (SCN)–ventral attention network (VAN) connectivity at baseline increased in patients with MDD after 12‐week treatment, and it was comparable with that of HCs. This change was only observed in patients with MDDr. However, the decreased within‐network rsFC in SCN and default mode network (DMN) persisted in all patients with MDD, including those with MDDr and MDDnr, after treatment. The strength of SCN–VAN connectivity at baseline was significantly negatively correlated with the reduction rate of HAMD score in all patients with MDD. Thus, SCN–VAN connectivity may be an antidepressant target associated with depressive state changes and a predictor of treatment response to serotonin reuptake inhibitors. The within‐network rsFC in SCN and DMN may reflect a trait‐like abnormality in MDD. These findings provide further insights into the mechanism of antidepressants and their individual differences in response. The trial name is “Appropriate technology study of MDD diagnosis and treatment based on objective indicators and measurement” (URL: http://www.chictr.org.cn/showproj.aspx?proj=21377; registration number: ChiCTR‐OOC‐17012566).