Written informed consent was obtained from all participants according to the approval of the ethics committee of the local institutional review board. Forty-four MOH patients and 32 normal controls were recruited from the International Headache Center, Department of Neurology, Chinese PLA General Hospital. All the following inclusion criteria should be fulfilled: 1) MOH refers to ICHD-III beta 8.2, and the definition of migraine refers to ICHD-III beta 1.1 and 1.2 [
37]; 2) no migraine preventive medication used in the past 3 months; 3) age between 20 and 60 years; 4) right-handed; 5) absence of any chronic disorders, including hypertension, hypercholesterolemia, diabetes mellitus, cardiovascular diseases, cerebrovascular disorders, neoplastic diseases, infectious diseases, connective tissue diseases, other subtypes of headache, chronic pain other than headache, severe anxiety or depression preceding the onset of headache, psychiatric diseases, etc.; 6) absence of alcohol, nicotine, or other substance abuse; and 7) patient’s willingness to engage in the study. Thirty-two normal controls (NCs) were recruited from the hospital’s staff and their relatives. Inclusion criteria were similar to those of patients, except for the first two items, and NCs should never have had any primary headache disorders or other types of headache in the past year. The exclusion criteria for NC and MOH were the following: cranium trauma, illness interfering with central nervous system function, psychotic disorder, and regular use of a psychoactive or hormone medication. General demographic and headache information were registered and evaluated in our headache database. Additionally, we evaluated anxiety, depression, and cognitive function of all the participants by using the Hamilton Anxiety Scale (HAMA) [
38], the Hamilton Depression Scale (HAMD) [
39], and the Montreal Cognitive Assessment (MoCA) Beijing Version (
www.mocatest.org). All the patients were given with the Visual Analogue Scale (VAS), migraine disability assessment (MIDSA), and a standard categorical four-grade sleep disturbance scale (SDS)(0, normal; 1, mild sleep disturbance; 2, moderate sleep disturbance; 3, serious sleep disturbance). MRI scans were taken in the interictal stage at least three days after a migraine attack for MOH patients. All the subjects were right-handed and underwent conventional MRI examination to exclude the subjects with cerebral infarction, malacia, or occupying lesions. Alcohol, nicotine, caffeine, and other substances were avoided for at least 12 h before MRI examination.