Altered Brain Functional Mechanisms In Lifelong Premature Ejaculation Patients:a Pilot Study

Premature ejaculation(PE)is one of the most common male sexual dysfunction disease,and lifelong PE,an important subtype of PE,not only damages male self-esteem,but also seriously reduces the quality of sexual life of PE patients and their sexual partners,and affects family harmony and happiness in life.Early research on PE mainly focused on psychological or biological hormones such as dopamine and serotonin,but recent studies on ejaculation have shown that the sympathetic and parasympathetic nervous systems were involved in the regulation and control of ejaculation.Therefore,in recent years people have studied the nervous system abnormalities of PE.The emergence and use of magnetic resonance imaging(MRI)technology has provided a convenient solution for people to study the abnormal neural mechanism of PE.However,there were still not many studies on PE patients based on MRI data and the specific neural mechanisms of PE were still not fully understood.Therefore,the main objectives of this thesis were to conduct preliminary research on the abnormal brain neural mechanisms of PE using functional MRI data of lifelong PE patients and healthy controls(HCs),and to find the possible associations between the abnormal imaging findings and clinical characteristics in the PE group.First,this paper investigated the abnormal mechanisms of brain functional networks in the patients with lifelong PE based on the voxel-wise degree centrality(DC)method.Forty-five lifelong PE patients and thirty-seven HCs were enrolled in this study and underwent T1-weighted and resting-state functional MRI scanning.The DC approach was applied to distinguish functional connectivity information abnormality within the whole-brain network between the lifelong PE patients and HCs.Correlation analysis was then performed to assess possible relationships between the DC alternations and clinical symptoms in the patient group.Compared with HCs,PE patients had increased DC values in the bilateral precuneus and right primary somatosensory cortex(SI)as well as decreased DC values in the bilateral insula and orbitofrontal cortex(OFC).And the significantly positive correlation was found between the mean DC value in the SI and Premature Ejaculation Diagnostic Tool(PEDT)score in the patient group.The present findings indicate that lifelong PE patients have altered DC values in several brain regions mainly related to neural processing of sensation,motivation and ejaculation inhibitory control,which may show the abnormal information processing implicated in forsaid several aspects of lifelong PE patients.Second,the recent several studies have reported the abnormalities of central nervous system implicated in the etiology of lifelong PE,including the striatum.In the present study,we aimed to investigate abnormal intrinsic connectivity of striatum in lifelong PE patients compared to HCs.Forty-seven lifelong PE patients and thirty HCs were enrolled in the present study and underwent structural and resting-state functional MRI scanning.The functional connectivity(FC)method was applied to investigate the altered striatum-related intrinsic connectivity in PE patients compared with HCs.Correlation analysis was performed to test the possible relationships between the imaging findings and clinical characteristics in the patient group.The results showed that compared with HCs,PE patients had significantly decreased FC between the right caudate and insula,superior temporal pole(STP)and OFC as well as decreased FC between the bilateral putamen and insula,STP and middle cingulate cortex.Meanwhile,PE patients had significantly increased FC between the left caudate and OFC,and increased FC between the right putamen and fusiform.The mean score from the right caudate-OFC,caudate-insula and caudate-STP connectivity negatively correlated with the PEDT score,separately.The current study showed the functional abnormality of lifelong PE in multiple brain regions implicated in sensation,motivation and ejaculation-related inhibitory control.Third,the hypothalamus is implicated in the ejaculatory control processing of healthy males.This study was to investigate abnormal intrinsic connectivity of hypothalamus in lifelong PE patients compared to HCs.Forty-seven lifelong PE patients and thirty HCs were included in the study.FC method was applied to investigate abnormal hypothalamus-seeded FC in the PE patients compared with HCs and correlation analysis was used to study the possible correlation between imaging findings and clinical characteristics in the patient group.Compared with HCs,PE patients had decreased hypothalamus-seeded FC in the left OFC,bilateral insula,superior temporal cortex,STP,middle temporal cortex,left fusiform,right parahippocampal gyrus and right cerebellum.The intravaginal ejaculatory latency time(IELT)positively correlated with the mean z-score from the hypothalamus-insula and hypothalamus-cerebellum intrinsic connectivity,separately.This study shown the hypothalamus-seeded FC alterations and the correlations between the aforementioned abnormal FC and IELT.The current findings may promote the understanding of the hypothalamus-related neural mechanisms involved in the abnormal ejaculatory information processing in lifelong PE patients.The results of this thesis showed that the neural mechanisms in lifelong PE patients were significantly changed compared to HCs,and showed the abnormal ejaculation-related brain information transmission,interaction,and processing implicated in sensory,motivation and inhibitory control in patients with lifelong PE.We hope that the results of this thesis complemented and improved the existing findings of PE imaging studies,put new insights into the pathophysiological abnormalities of PE and provided imaging basis for improving the clinical diagnosis and treatment of PE.