Altered Amplitude Of Low Frequency Fluctuation And Functional Connectivity In Primary Dysmenorrhea

Primary dysmenorrhea(PDM),defined as menstrual pain with normal pelvic anatomy,is a common gynecological disorder in adolescent girls and women of reproductive age.It is characterized by cramping pain originating from the lower abdomen and may radiate to the inner side of thighs.Sometimes PDM is even accompanied by nausea,backaches,fatigue,diarrhea,sleeplessness,or nervousness.Epidemiological studies reported that 20% to 90% of female adolescents have experienced dysmenorrhea,and 10%-20% have had severe pain.Many factors,such as prostaglandins,interleukin-6 and vasopressin,are proposed as contributors to the pathogenesis of PDM.However,the exact pathophysiology of PDM is not completely understood.Recently,neuroimaging studies have demonstrated that PDM is associated with brain structural and functional alterations.In this study,we tried to use resting-state functional magnetic resonance imaging data from forty-eight PDM patients and thirty-eight matched female healthy controls to investigate changes of intrinsic brain activity in PDM.Firstly,amplitude of low-frequency fluctuation(ALFF)and functional connectivity(FC)methods were applied to examine changes in the default mode network(DMN)in PDM patients.We found increased ALFF in the right precuneus,bilateral dm PFC and bilateral anterior cingulate cortex(ACC),and decreased ALFF in the bilateral thalamus.In addition,we found a significant positive correlation between the disease duration and the ALFF in the left dm PFC in PDM patients.PDM patients had decreased connectivity between the precuneus and left dm PFC and right ACC,and increased connectivity between the precuneus and left thalamus.Our findings provide further evidence of the DMN-related abnormalities in PDM patients which might contribute to a better understanding of the pathophysiology of this disease.Secondly,we systematically investigated connectivity changes of subregions of the ACC network in PDM.Compared to healthy controls,PDM patients exhibited increased connectivity between the caudal ACC and primary somatosensory cortex,between the perigenual ACC and caudate,and between the subgenual ACC and medial prefrontal cortex.PDM patients also showed decreased connectivity between the perigenual ACC and precuneus.In PDM group,the connectivity of the right perigenual ACC-right caudate positively correlated with disease duration,and the connectivity of the left p ACC-left precuneus negatively correlated with disease severity.These present findings reveal that abnormal ACC connectivity may be implicated in the PDM-related disturbances in pain sensory,modulation,and affection.In summary,our findings provide preliminary evidence of the intrinsic brain activity abnormalities in PDM patients which might contribute to a better understanding of the pathophysiology of this disease and thereby improving the treatment of PDM.