, according to researchers. This increased connectivity is associated with clinical and affective measures. The data suggest that changes in the amygdala’s structure and function may play a role in the transformation to chronic migraine, according to the researchers. The study was presented online as part of the American Academy of Neurology’s 2020 Science Highlights.
Approximately 3% of patients with episodic migraine progress to chronic migraine each year. Chronic migraine is associated with increased headache frequency, greater disability, and increased psychiatric comorbidities. The pathophysiological mechanisms of the transformation from episodic to chronic migraine are not completely understood.
, instructor in neurology at Stanford (Calif.) University, and colleagues sought to investigate the role of the amygdala in the transformation of migraine. The amygdala is involved in nociceptive processing, emotional responses, and affective states such as depression and anxiety. Researchers have suggested that alterations in the structure or function of the amygdala might contribute to the worsening of pain and mood that coincides with the transformation of migraine.
Dr. DeSouza and colleagues enrolled 88 patients with migraine, diagnosed according to International Classification of Headache Disorders–3 criteria, in their study. Forty-four patients (36 women; mean age, 37.8 years) had chronic migraine, and 44 patients (36 women; mean age, 37.5 years) had episodic migraine. Participants underwent 3T MRI scanning during which investigators acquired T1-weighted structural and resting-state images of the brain. Participants also completed self-report questionnaires to evaluate depression and somatization (Patient Health Questionnaire), anxiety (Generalized Anxiety Disorder 7-item scale), pain catastrophizing (Pain Catastrophizing Scale), headache frequency, and headache intensity.
The investigators examined resting-state functional connectivity between the amygdala and the following three brain networks: DMN, salience network (SN), and central executive network (CEN). They assessed amygdala volume with voxel-based morphometry.
Analyses indicated that connectivity between the left amygdala and the DMN (i.e., the medial prefrontal cortex and the precuneus/posterior cingulate cortex) was increased in patients with chronic migraine, compared with those with episodic migraine. In all patients, resting-state functional connectivity between the amygdala and the DMN was positively associated with headache frequency. Connectivity between the left amygdala and the SN was positively associated with headache intensity, and connectivity between the right amygdala and the CEN was positively associated with pain catastrophizing. Both of these findings held in all patients.
In addition, Dr. DeSouza and colleagues found that bilateral amygdala volumes, including the basolateral and superficial/corticoid nuclei, were increased in patients with chronic migraine, compared with those with episodic migraine. Headache intensity and depression predicted differences in right amygdala volume, and depression alone predicted differences in left amygdala volume.
Dr. DeSouza reported no disclosures. One of the investigators acts as an adviser to Alder, Allergan, Amgen, Biohaven, Curex, Teva, and Xoc about matters unrelated to this study.
SOURCE: DeSouza DD et al. AAN 2020, .