To replicate the findings of reported functional connectivity (FC) alterations between cortical networks in chronic (CM) compared to controls, extend them to episodic (EM) migraine, and determine associations with headache frequency and severity.

There is a growing literature demonstrating resting-state FC alterations in CM. However, mixed methods and patient samples have led to differences in the brain regions/networks implicated. Recently, FC alterations in patients with CM without medication overuse (-MO) were demonstrated in three major cortical networks compared to healthy controls (default mode (DMN), executive control (ECN), and dorsal attention (DAS)) and were associated with headache severity. We aimed to replicate this study in a separate cohort of patients with CM -MO and expand these findings by examining CM patients with MO (+MO) and episodic migraine (EM).    

125 participants (44 CM patients (27 +MO and 17 -MO), 44 EM patients, and 37 healthy controls) completed resting-state fMRI scans at 3T to compare FC between cortical networks using independent component analysis. Associations between FC and headache frequency and severity were evaluated.

Five cortical networks were identified as having good spatial overlap across groups: DMN, DAS, ECN, visual (VN), and sensorimotor (SMN). Compared to controls, CM patients  (+MO and -MO) had lower DMN-SMN FC. Compared to EM, CM patients (-MO only) had greater VN-DAS FC and lower VN-DMN FC. VN-DAS FC was positively associated with headache frequency and VN-DMN FC was negatively associated with headache frequency.

We provide evidence for altered cortical network FC in CM patients compared to healthy controls and EM patients; however, we did not replicate previous findings. Our extended findings of CM FC alterations compared to EM were specific to patients -MO and related to headache frequency suggesting distinct correlates of headache changes from patients +MO.