Graph analysis of DTI ‐based connectome: decreased local efficiency of subcortical regions in PE patients with high sympathetic activity

Topological differences of striato-thalamo-cortical circuit in functional brain network between premature ejaculation patients with and without depression

INTRODUCTION

Premature ejaculation (PE), a common male sexual dysfunction, often accompanies by abnormal psychological factors, such as depression. Recent neuroimaging studies have revealed structural and functional brain abnormalities in PE patients. However, there is limited neurological evidence supporting the comorbidity of PE and depression. This study aimed to explore the topological changes of the functional brain networks of PE patients with depression.

METHODS

Resting-state functional magnetic resonance imaging (rs-fMRI) data were acquired from 60 PE patients (30 with depression and 30 without depression) and 29 healthy controls (HCs). Functional brain networks were constructed for all participants based on rs-fMRI data. The nodal parameters including nodal centrality and efficiency were calculated by the method of graph theory analysis and then compared between groups. In addition, the results were corrected for multiple comparisons by family-wise error (FWE) (p < .05).

RESULTS

PE patients with depression had increased degree centrality and global efficiency in the right pallidum, as well as increased degree centrality in the right thalamus when compared with HCs. PE patients without depression showed increased degree centrality in the right pallidum and thalamus, as well as increased global efficiency in the right precuneus, pallidum, and thalamus when compared with HCs. PE patients with depression demonstrated decreased degree centrality in the right pallidum and thalamus, as well as decreased global efficiency in the right precuneus, pallidum, and thalamus when compared to those without depression. All the brain regions above survived the FWE correction.

CONCLUSION

The results suggested that increased and decreased functional connectivity, as well as the capability of global integration of information in the brain, might be related to the occurrence of PE and the comorbidity depression in PE patients, respectively. These findings provided new insights into the understanding of the pathological mechanisms underlying PE and those with depression.

Ultra-high field imaging of the amygdala - A narrative review

The amygdala is an evolutionarily conserved core structure in emotion processing and one of the key regions of interest in affective neuroscience. Results of neuroimaging studies focusing on the amygdala are, however, often heterogeneous since it is composed of functionally and neuroanatomically distinct subnuclei. Fortunately, ultra-high-field imaging offers several advances for amygdala research, most importantly more accurate representation of functional and structural properties of subnuclei and their connectivity. Most clinical studies using ultra-high-field imaging focused on major depression, suggesting either overall rightward amygdala atrophy or distinct bilateral patterns of subnuclear atrophy and hypertrophy. Other pathologies are only sparsely covered. Connectivity analyses identified widespread networks for learning and memory, stimulus processing, cognition, and social processes. They provide evidence for distinct roles of the central, basal, and basolateral nucleus, and the extended amygdala in fear and emotion processing. Amid largely sparse and ambiguous evidence, we propose theoretical and methodological considerations that will guide ultra-high-field imaging in comprehensive investigations to help disentangle the ambiguity of the amygdala's function, structure, connectivity, and clinical relevance.

Potential biomarkers for distinguishing primary from acquired premature ejaculation: A diffusion tensor imaging based network study

Introduction

Premature ejaculation (PE) is classified as primary and acquired and may be facilitated by different pathophysiology. Brain plays an important role in PE, however, differences in the central neuropathological mechanisms among subtypes of PE are unknown.

Materials and methods

We acquired diffusion tensor imaging (DTI) data from 44 healthy controls (HC) and 47 PE patients (24 primary PE and 23 acquired PE). Then, the whole-brain white matter (WM) structural networks were constructed and between-group differences of nodal segregative parameters were identified by the method of graph theoretical analysis. Moreover, receiver operating characteristic (ROC) curves were performed to determine the suitability of the altered parameters as potential neuroimaging biomarkers for distinguishing primary PE from acquired PE.

Results

PE patients showed significantly increased clustering coefficient C(i) in the left inferior frontal gyrus (triangular part) (IFGtriang.L) and increased local efficiency E_loc(i) in the left precental gyrus (PreCG.L) and IFGtriang.L when compared with HC. Compared to HC, primary PE patients had increased C(i) and E_loc(i) in IFGtriang.L and the left amygdala (AMYG.L) while acquired PE patients had increased C(i) and E_loc(i) in IFGtriang.L, and decreased C(i) and E_loc(i) in AMYG.L. Compared to acquired PE, primary PE patients had increased C(i) and E_loc(i) in AMYG.L. Moreover, ROC analysis revealed that PreCG.L, IFGtriang.L and AMYG.L might be helpful for distinguishing different subtypes of PE from HC (PE from HC: sensitivity, 61.70–78.72%; specificity, 56.82–77.27%; primary PE from HC: sensitivity, 66.67–87.50%; specificity, 52.27–77.27%; acquired PE from HC: sensitivity, 34.78–86.96%; specificity, 54.55–100%) while AMYG.L might be helpful for distinguishing primary PE from acquired PE (sensitivity, 83.33–91.70%; specificity, 69.57–73.90%).

Conclusion

These findings improved our understanding of the pathophysiological processes that occurred in patients with ejaculatory dysfunction and suggested that the abnormal segregation of left amygdala might serve as a useful marker to help clinicians distinguish patients with primary PE from those with acquired PE.

Selecting Multiple Node Statistics Jointly from Functional Connectivity Networks for Brain Disorders Identification

Functional connectivity networks (FCN) analysis is instructive for the diagnosis of brain diseases, such as mild cognitive impairment (MCI) and major depressive disorder (MDD) at their early stages. As the critical step of FCN analysis, feature representation provides the basis for finding potential biomarkers of brain diseases. In previous studies, different node statistics (e.g. local efficiency and local clustering coefficients) are usually extracted from FCNs as features for the diagnosis/classification task, which can specifically locate disease-related regions on the node level, so as to help us understand the neurodevelopmental roots of brain disorders. However, each node statistic is proposed only considering a kind of specific network property, which has one-sidedness and limitations. As a result, it is incomplete to represent a node with only one statistic. To resolve this issue, we put forward a novel scheme to select multiple node statistics jointly from the estimated FCNs for automated classification, called multiple node statistics feature selection (MNSFS). Specifically, we first extract multiple statistics from the same nodes and assign each kind of statistic into a group. Then, sparse group least absolute shrinkage and selection operator (sgLASSO) is used to select groups (nodes) and statistics in the groups towards a better classification performance. Such a technique enables us to simultaneously locate the discriminative brain regions, as well as the specific statistics associated with these brain regions, making the classification results more interpretable. We conducted our scheme on two public databases for identifying subjects with MCI and MDD from normal controls. Experimental results show that the proposed scheme achieves superior classification accuracy and features interpreted on the benchmark datasets.

Thalamocortical Dysconnectivity In Lifelong Premature Ejaculation: A Functional MRI Study

OBJECTIVES

To detect seed-based functional connectivity (FC) between various cortical sub-regions and the thalamus in lifelong premature ejaculation (LPE) patients and explore whether specific thalamocortical networks are significantly altered in PE patients compared to healthy controls (HCs) METHODS: Fifty non-medicated LPE patients and 40 age-matched HCs underwent a resting-state functional MRI. FC was adopted to identify specific thalamocortical connectivity between the thalamus and 6 cortical regions of interest (i.e., the motor cortex/supplementary motor, the prefrontal cortex, the temporal lobe, the posterior parietal cortex, the somatosensory cortex and the occipital lobe). In LPE patients, regression analysis was subsequently conducted to assess relationships of thalamocortical connectivity with the Premature Ejaculation Diagnostic Tool (PEDT) score and the Intravaginal Ejaculatory Latency Time (IELT).

RESULTS

LPE patients had significantly decreased FC between the motor cortex and bilateral ventral thalamus, between the prefrontal cortex and left dorsomedial thalamus, as well as between the temporal cortex and bilateral ventromedial thalamus. In LPE patients, PEDT score was significantly positively associated with the thalamus-posterior parietal cortex FC, and negatively associated with the thalamus-temporal cortex FC, while IELT was positively associated with the thalamus-temporal cortex and thalamus-motor cortex FC.

CONCLUSION

These results enrich the imaging evidence for the understanding of the neurobiological mechanisms and/or consequences of LPE.

Reconfiguration of Dynamic Functional Connectivity States in Patients With Lifelong Premature Ejaculation

Purpose: Neuroimaging has demonstrated altered static functional connectivity in patients with premature ejaculation (PE), while studies examining dynamic changes in spontaneous brain activity in PE patients are still lacking. We aimed to explore the reconfiguration of dynamic functional connectivity (DFC) states in lifelong PE (LPE) patients and to distinguish LPE patients from normal controls (NCs) using a machine learning method based on DFC state features. Methods: Thirty-six LPE patients and 23 NCs were recruited. Resting-state functional magnetic resonance imaging (fMRI) data, the clinical rating scores on the Chinese Index of PE (CIPE), and intravaginal ejaculatory latency time (IELT) were collected from each participant. DFC was calculated by the sliding window approach. Finally, the Lagrangian support vector machine (LSVM) classifier was applied to distinguish LPE patients from NCs using the DFC parameters. Two DFC state metrics (reoccurrence times and transition frequencies) were introduced and we assessed the correlations between DFC state metrics and clinical variables, and the accuracy, sensitivity, and specificity of the LSVM classifier. Results: By k-means clustering, four distinct DFC states were identified. The LPE patients showed an increase in the reoccurrence times for state 3 (p < 0.05, Bonferroni corrected) but a decrease for state 1 (p < 0.05, Bonferroni corrected) compared to the NCs. Moreover, the LPE patients had significantly less frequent transitions between state 1 and state 4 (p < 0.05, uncorrected) while more frequent transitions between state 3 and state 4 (p < 0.05, uncorrected) than the NCs. The reoccurrence times and transition frequencies showed significant associations with the CIPE scores and IELTs. The accuracy, sensitivity, and specificity of the LSVM classifier were 90.35, 87.59, and 85.59%, respectively. Conclusion: LPE patients were more inclined to be in DFC states reinforced intra-network and inter-network connection. These features correlated with clinical syndromes and can classify the LPE patients from NCs. Our results of reconfiguration of DFC states may provide novel insights for the understanding of central etiology underlying LPE, indicate neuroimaging biomarkers for the evaluation of clinical severity of LPE.

Is heart rate variability a risk factor for premature ejaculation?

OBJECTIVE

The purpose of this study is to assess the parameters of heart rate variability, which is an indicator of the change in autonomic nervous system (ANS) activity, in individuals with premature ejaculation (PE).

MATERIAL AND METHODS

This study was performed by comparing 40 patients with PE (mean age, 31.2 ± 4.1 years) and 40 healthy individuals (mean age, 30.4 ± 4.8 years) without PE from May 2018 to December 2019. HRV parameters were compared between men with PE and healthy controls in 24-hour heart rhythm Holter examination.

RESULTS

In the time domain analysis, which is a subgroup of HRV, square root of differences between consecutive normal NN intervals (RMSSD), which is an indicator of parasympathetic activity, was lower in patients with PE compared with controls (P = .025). Moreover, within the frequency domain analysis, high frequency (HF), another indicator of parasympathetic activity, was lower in patients compared with controls (P = .032). Finally, the LF/HF ratio, reflecting sympathetic/parasympathetic activity ratio, was significantly higher in patients compared with controls (P = .008). Furthermore, the multivariate logistic regression analysis showed that LF/HF ratio is independently associated with PE (P = .005). The ROC curve analysis showed that the optimal cut-off value of LF/HF above 2.7 predicted PE at a sensitivity of 77.5% and specificity of 82.5% (positive predictive value: 81.5% and negative predictive value: 78.5%).

CONCLUSION

Different HRV parameters were exhibited in the comparison of patients with PE and normal controls. It suggests that the change in HRV parameters will be an indicator of imbalance in ANS and this imbalance may cause PE. Therefore, HRV analysis can be a diagnostic tool to assess altered ANS activity in patients with PE and may be considered as a rapid screening tool.

Abnormal Functional Connectivity Between the Left Medial Superior Frontal Gyrus and Amygdala Underlying Abnormal Emotion and Premature Ejaculation: A Resting State fMRI Study

Introduction

Premature ejaculation (PE) is a common sexual dysfunction and is found to be associated with abnormal emotion. The amygdala plays an important role in the processing of emotion. The process of ejaculation is found to be mediated by the frontal-limbic neural circuits. However, the correlations between PE and emotion are still unclear.

Methods

Resting-state functional magnetic resonance imaging (rs-fMRI) data were acquired in 27 PE patients with stable emotion (SPE), 27 PE patients with abnormal emotion (NPE), and 30 healthy controls (HC). We used rs-fMRI to explore the underlying neural mechanisms in SPE, NPE, and HC by measuring the functional connectivity (FC). Differences of FC values among the three groups were compared when choosing bilateral amygdala as the regions of interest (ROIs). We also explored the correlations between the brain regions showing altered FC values and scores of the premature ejaculation diagnostic tool (PEDT)/Eysenck Personality Inventory about neuroticism (EPQ-N) in the PE group.

Results

When the left amygdala was chosen as the ROI, the SPE group exhibited an increased FC between the left medial superior frontal gyrus (SFGmed) and amygdala compared with the NPE or HC group. When the right amygdala was chosen as the ROI, the NPE group exhibited a decreased FC between the left SFGmed and right amygdala compared with the HC group. In addition, FC values of the left SFGmed had positive correlations with PEDT and negative correlations with EPQ-N scores in the PE group. Moreover, FC values of the left superior temporal gyrus had positive correlations with EPQ-N scores in the PE group.

Conclusion

The increased FC values between the left SFGmed and amygdala could reflect a compensatory cortical control mechanism with the effect of stabilized emotion in the limbic regions of PE patients. Abnormal FC between these brain regions could play a critical role in the physiopathology of PE and could help us in dividing PE into more subtypes.

Magnetic Resonance Imaging-Based Structural Covariance Changes of the Striatum in Lifelong Premature Ejaculation Patients

BACKGROUND

The striatum has been reported to be implicated in various neurological diseases, including lifelong premature ejaculation (LPE). Altered striatum-related functional connectivity was investigated in LPE patients in previous studies; however, structural abnormalities in the striatum have been less studied in LPE.

PURPOSE

To identify the gray matter volume (GMV) and structural covariance patterns of the striatum between LPE patients and healthy controls (HCs).

STUDY TYPE

Prospective.

SUBJECTS

Forty-three LPE patients and 31 male HCs.

FIELD STRENGTH/SEQUENCE

3.0 T magnetic resonance imaging (MRI) scanner; T1-weighted imaging using a spoiled gradient recalled echo sequence.

ASSESSMENT

Preprocessing of structural MRI data and the striatum-seeded GMV computation were conducted using SPM12.

STATISTICAL TESTS

Two sample t-test was used to compare differences in GMV of the striatum between patients and HCs. Regions showing altered between-group GMV were considered as seeds for structural covariance analysis in two groups. Additionally, correlations between GMV findings and clinical features were assessed with age and total intracranial volume (TIV) as covariates and with age, TIV, anxiety, and depression scores as covariates in the patient group, P < 0.05 was considered statistically significant.

RESULTS

Compared to HCs, LPE patients had significantly decreased GMV in four regions located in the bilateral caudate and putamen. Distinct striatum-based structural covariance patterns in the two groups were mainly related to the thalamus, amygdala, insula, anterior cingulate cortex, middle cingulate cortex, medial prefrontal cortex, primary motor cortex, and precuneus/cuneus. LPE patients showed that GMV in the bilateral caudate negatively correlated with the premature ejaculation diagnostic tool (PEDT) scores (r = -0.369, r = -0.377, respectively).

DATA CONCLUSION

Our findings indicated that LPE patients had altered GMV and structural covariance patterns in the striatum compared to HCs. The correlations between abnormal GMV and PEDT were also shown in the present findings. These findings may contribute to enhancing the understanding of the pathophysiology of LPE.

LEVEL OF EVIDENCE

1 TECHNICAL EFFICACY: Stage 3.

Altered Structural and Functional Connectivity Contribute to Rapid Ejaculation: Insights from a Multimodal Neuroimaging Study

Little is known about how the aberrant structural and functional connectivity relates to the rapid ejaculation. Data of diffusion tensor imaging and resting state functional magnetic resonance imaging were acquired from 32 PE patients and 38 healthy controls (HCs). Firstly, we investigated the structural connectivity (SC) disruptions of PE patients using the method of graph theoretical analysis. Brain regions with impaired nodal strength were then defined as regions of interest (ROI). Secondly, the corresponding functional connectivity (FC) changes were explored. Finally, the correlation analyses were performed between brain areas with abnormal connectivity and clinical characteristics. Structural analysis revealed that PE patients had increased nodal strength in the right superior frontal gyrus (dorsolateral), left middle frontal gyrus, right superior frontal gyrus (medial), right superior frontal gyrus (medial orbital) and decreased nodal strength in the left amygdala. FC analysis revealed that PE patients had decreased FC values in the default mode network, visual recognition network and subcortical network, as well as increased FC values in the attention network. Moreover, correlation analysis revealed that the nodal strength of right superior frontal gyrus (dorsolateral) was negatively associated with the intra-vaginal ejaculation latency, while FC values between the left middle frontal gyrus and middle occipital gyrus were positively related to the total scores of the premature ejaculation diagnostic tool (PEDT). Our results indicated that PE might be associated with the abnormal SC of areas in the prefrontal-amygdala pathway and aberrant FC in certain functional brain networks, especially in default mode network.

Abnormal Thalamic Metabolism in Patients With Lifelong Premature Ejaculation

BACKGROUND

Although some recent neuroimaging studies have indicated the abnormal brain structure or function in patients with lifelong premature ejaculation (LPE), whether and how the abnormal thalamic function participates in processing sexual behavioral information are still unclear in patients with LPE.

AIM

The aim of this study was to assess the changes in the thalamus metabolism and structural integrity in patients with LPE.

METHODS

We performed a multimodal magnetic resonance approach in a 3.0 T system, including proton magnetic resonance spectroscopy (¹H-MRS), diffusion tensor imaging, and volumetric analysis to detect the differences in thalamic metabolism and structure between 20 patients with LPE and 15 healthy controls.

OUTCOMES

We analyzed and correlated the clinical symptoms of the subjects with significant ¹H-MRS-based features. Peak areas of N-acetylaspartate, choline, creatine (Cr), and glutamate/glutamine (Glu) were calculated with the LCModel software.

RESULTS

Diffusion tensor imaging and volumetric analysis of thalami showed no differences between the 2 groups. On the contrary, ¹H-MRS study disclosed that both Glu concentrations and Glu/Cr ratio values in the thalami of patients with LPE were remarkably increased when compared with healthy controls (P < .01 for both variables). In addition, both the intravaginal ejaculatory latency time score and Chinese Index of Sexual Function for Premature Ejaculation-5 score were negatively related to increased Glu concentrations and Glu/Cr ratio values.

CLINICAL IMPLICATIONS

Glutamatergic activity changes of thalamus may be an underlying indicator for evaluating sensory conduction efficiency in patients with LPE.

STRENGTHS & LIMITATIONS

The present study first found the abnormal thalamic metabolism in patients with LPE and contributed to a better understanding of the LPE etiology. Limitations include a cross-sectional study design with small samples and no examination of other brain areas.

CONCLUSION

Our findings show that the increase in glutamatergic activity of thalamus is related to LPE, suggesting that the increased Glu neurotransmission in the thalamus may contribute to the development of premature ejaculation. Xia J-D, Chen F, Zhang Q-J, et al. Abnormal Thalamic Metabolism in Patients With Lifelong Premature Ejaculation. J Sex Med 2021;18:275-283.

The heart rate recovery is impaired in participants with premature ejaculation

Premature ejaculation (PE) is one of the most common sexual disorders in men. Excessive activity of the sympathetic nervous system is considered as one of the pathological mechanisms of PE. Heart rate recovery (HRR) is a noninvasive and easily applicable method for evaluating autonomic functions. We aimed to investigate the relationship between PE and HRR. This cross-sectional study included 42 consecutive patients with lifelong PE and 98 healthy volunteers. All participants underwent stress tests according to age-dependent target heart rates outlined in the Bruce protocol. When the maximal heart rate was reached in the stress test, intensive exercise was terminated and electrocardiographic records were obtained for 3 min in the cool-down period. The HRR indices were calculated by subtracting the heart rate at first, second and third minutes from the maximal HR. The two groups were similar in terms of age, body mass index, serum glucose and lipid parameters. HRR indices were significantly lower in the PE group compared with the control group (p < .05 for all). Common factors that affect equilibrium of sympathetic and parasympathetic nervous systems may be involved in the PE and abnormal HRR etiopathogenesis. The cause-and-effect relationship can be more clearly demonstrated with large-scale, prospective studies.

Altered Functional Connectivity of Hypothalamus in Lifelong Premature Ejaculation Patients

BACKGROUND

As one of the most prevalent sexual dysfunctions in men, lifelong premature ejaculation (PE) often leads to patient distress. The hypothalamus is implicated in the ejaculatory control of healthy males. However, we do not know whether the hypothalamus-related intrinsic connectivity is altered in lifelong PE patients.

PURPOSE

To investigate abnormal intrinsic connectivity of the hypothalamus in lifelong PE patients compared with healthy controls (HCs).

STUDY TYPE

Prospective pilot study using cross-sectional data of patients and HCs.

SUBJECTS

Forty-seven lifelong PE patients and 30 HCs were included in this study.

FIELD STRENGTH/SEQUENCE

3.0T MRI scanner for T₁ -weighted imaging using spoiled gradient recalled echo sequence and functional imaging using a single-shot gradient recalled echo sequence.

ASSESSMENT

Preprocessing of MRI data and hypothalamus-seeded functional connectivity (FC) computation were performed using DPABI4.1.

STATISTICAL TESTS

The two-sample t-test within SPM12 was adopted to examine possible alterations of intrinsic connectivity of hypothalamus in lifelong PE patients compared with HCs including anxiety and depression scores as covariates (false discovery rate-corrected, P < 0.05). The correlation analysis was then used to assess possible associations between the imaging findings and clinical features in the patient group (Bonferroni-corrected, P < 0.05).

RESULTS

Compared with HCs, lifelong PE patients had decreased hypothalamus-seeded FC in the left orbitofrontal cortex, bilateral insula, superior temporal cortex, superior temporal pole, middle temporal cortex, left fusiform, right parahippocampal gyrus, and right cerebellum. The intravaginal ejaculatory latency time positively correlated with the mean z-score from the hypothalamus-insula (r = 0.45) and hypothalamus-cerebellum (r = 0.48) intrinsic connectivity, separately.

DATA CONCLUSION

We have shown that hypothalamus-seeded FC alterations and the correlations between the aforementioned abnormal FC alterations and intravaginal ejaculatory latency time. The current findings may promote the understanding of the hypothalamus-related neural mechanisms involved in the abnormal ejaculatory information processing in lifelong PE patients.

LEVEL OF EVIDENCE

1 TECHNICAL EFFICACY STAGE: 3 J. Magn. Reson. Imaging 2020;52:778-784.

Associations Between Altered Cerebral Activity Patterns and Psychosocial Disorders in Patients With Psychogenic Erectile Dysfunction: A Mediation Analysis of fMRI

Previous studies had illustrated the significant neural pathological changes in patients with psychogenic erectile dysfunction (pED), while few works focused on the neural underpinning of the psychosocial status in patients with pED. This study aimed to investigate the associations among the altered cerebral activity patterns, impaired erectile function, and the disrupted psychosocial status in patients with pED. Thirty-two patients with pED and 28 healthy controls (HCs) were included. The amplitude of low-frequency fluctuations (ALFF), region-of-interest-based functional connectivity (FC), as well as Pearson correlation analyses and mediation analyses between neuroimaging outcomes and clinical outcomes were performed. Compared to HCs, patients with pED manifested lower erectile function, disrupted psychosocial status, as well as decreased ALFF in the left dorsolateral prefrontal cortex (dlPFC) and reduced FC between the left dlPFC and left angular gyrus, and left posterior cingulate cortex (PCC) and precuneus, which belonged to the default mode network (DMN). Moreover, both the ALFF of the left dlPFC and FC between the left dlPFC and left PCC and precuneus were significantly correlated with the sexual function and psychosocial status in patients with pED. The disrupted psychosocial status mediated the influence of atypical FC between dlPFC and DMN on decreased erectile function. This study widened our understanding of the important role of psychosocial disorders in pathological neural changes in patients with pED.