The relationship between the second-to-fourth digit ratios and lifelong premature ejaculation: a prospective, comparative study

Higher inter-hemispheric homotopic connectivity in lifelong premature ejaculation patients: a pilot resting-state fMRI study

Background

Lifelong premature ejaculation (PE) is one common male sexual dysfunction and is implicated in widespread structural and functional abnormalities of bilateral hemispheres. However, whether the inter-hemisphere functional connectivity (FC) of lifelong PE patients was altered still remain unclear.

Methods

Thirty-four lifelong PE patients and 30 healthy controls (HCs) were enrolled in this study and all underwent T1-weighted and resting-state functional MRI (fMRI) scan. The voxel-mirrored homotopic connectivity (VMHC) measure and independent sample t-test were applied to examine the alterations of VMHC values in the patients relative to HCs with the significant threshold at P<0.05, false discovery rates corrected. Correlation analysis was adopted to calculate the relationships between the imaging results and clinical characteristics of patients (P<0.05, Bonferroni corrected). Receiver operating characteristic (ROC) curve analysis was performed to investigate the possible biomarkers for distinguishing the patients from the HCs using the VMHC values of inter-group differences.

Results

The results revealed that compared with HCs, lifelong PE patients had higher VMHC values in the precentral gyrus (PG), primary somatosensory cortex (S1), supplementary motor area (SMA), precuneus, middle temporal cortex (MTC), superior temporal pole (STP), thalamus, caudate and middle cingulate cortex (MCC). Correlation analysis showed that the mean VMHC values in the S1 negatively correlated with intravaginal ejaculation latency time (IELT) in the patient group. Furthermore, the caudate revealed the well classification power from the ROC analysis.

Conclusions

The present study showed the abnormal inter-hemisphere interaction and integration of information involved in ejaculation inhibitory control, sensorimotor mediation and self-reference processing including the thalamus, caudate, MCC, widespread parietal cortex and temporal cortex in lifelong PE patients compared with HCs. Correlation analysis and ROC analysis revealed the importance of S1 and caudate in lifelong PE. Notably, the ROC result of caudate might show the core roles of caudate played in the pathophysiology of lifelong PE.

Prenatal exposure to bisphenol analogues and digit ratio in children at ages 4 and 6 years: A birth cohort study

Bisphenol analogues (BPs), including bisphenol A (BPA), have been shown to exhibit similar endocrine disrupting activities. However, epidemiological evidence on the reproductive and developmental toxicities of BPs other than BPA is scarce. The second to fourth digit ratio (2D:4D), an endocrine-sensitive endpoint, has been suggested to be a biomarker of prenatal sex steroid exposure and associated with reproductive outcomes in later life. Using the data of 545 mother-child pairs from the Shanghai-Minhang Birth Cohort Study, we prospectively assessed the effects of prenatal exposure to BPs on 2D:4D in children at ages 4 and 6 years. Single-spot urine samples were collected in the third trimester and analyzed for BPs. Digit lengths were measured using a vernier caliper in children at ages 4 and 6 years, and the 2D:4D values for both hands were calculated. A multivariable linear regression model was applied to examine associations between prenatal BPs exposure and 2D:4D digit ratios at each age separately. The generalized estimating equation (GEE) model was used to deal with repeated 2D:4D measures obtained at ages 4 and 6 years. We found that prenatal exposure to BPA alternatives including BPF, BPS, and BPAF was associated with higher digit ratio in boys and/or girls (feminizing), while TCBPA, a halogenated bisphenol, was associated with lower 2D:4D in boys (masculinizing). These associations were more pronounced at 4 years of age, and tended to remain after further considering the potential confounding from prenatal co-exposure to other BPs and childhood BPs exposure. Our study provides epidemiological evidence that BPs exposure during pregnancy may alter the digit development in children, indicative of disrupted reproductive development in later life. Given these new findings, further studies are needed to corroborate our results.

Markers of Prenatal Androgen Exposure Correlate With Online Sexual Compulsivity and Erectile Function in Young Men

Pornography addiction and sexual dysfunction are increasingly prevalent in young men. Previous studies suggest that prenatal androgen exposure plays a role in addiction and sexual functionality. Here, we tested whether lower second-to-fourth finger length ratio (2D:4D) and later age at spermarche, both putative indicators of higher androgen levels in utero, correlate with online sexual compulsivity (OSC scale of ISST), erectile function (IIEF-5), and ejaculatory control (PEPA) in 4,370 young men (age IQR: 25-26 years) of the Cohort Study on Substance Use Risk Factors. Statistical analyses revealed that lower 2D:4D correlated with higher scores on the OSC scale. Moreover, higher age at spermarche correlated with higher OSC scores and decreased erectile function. Interestingly, OSC severity, but not the frequency of pornography use, correlated negatively with erectile function and ejaculatory control. This is the first study to associate two independent proxies of prenatal testosterone level with OSC. These findings provide novel insight into intrauterine predisposition of sexual behavior and related sexual function in adulthood.

Effects of prenatal exposure to polybrominated diphenyl ethers (PBDEs) on the second to fourth digit ratio in children aged 4 years

BACKGROUND

The second to fourth digit ratio (2D:4D) is assumed to be a biomarker of prenatal sex steroid exposure, correlating negatively with prenatal testosterone and positively with prenatal estrogen. The ratio has been suggested to be influenced by endocrine disrupting chemicals (EDCs). However, evidence regarding effects of prenatal exposure to polybrominated diphenyl ethers (PBDEs) on 2D:4D of children was sparse.

OBJECTIVES

We investigated the associations between prenatal exposure to PBDEs and 2D:4D of children aged 4 years.

METHODS

Participants were mother-child pairs from the Shanghai-Minhang Birth Cohort Study (S-MBCS) which enrolled pregnant women at 12-16 weeks of gestation from April to December 2012. Nine PBDE congeners in venous umbilical cord plasma of 340 children were measured. Digit lengths were measured using a vernier caliper in children aged 4 years and 2D:4D for left and right hands and average 2D:4D value of both hands were calculated. A total of 281 children (160 boys and 121 girls) who had data on both 2D:4D and PBDE concentrations were included in the final analysis. Associations between prenatal PBDE exposures and 2D:4D were investigated using multiple linear regression models.

RESULTS

Among the nine congeners, BDE-47 had the highest detection rate of 86.12% with the highest median concentration of 0.20 ng/ml lipid. Five PBDE congeners with detection rates greater than or close to 50% (BDE-28, -47, -99, -100 and -153) and Σ₅PBDEs (the sum of them) were included in final analysis. For girls, a consistent pattern for the positive associations between prenatal PBDE exposures and 2D:4D of children was observed mainly for the left hand, where those in the highest exposure groups had higher 2D:4D compared to the lowest exposure groups (a feminizing effect), with statistically significant associations observed for BDE-47 (β = 0.0247, 95% confidence interval (CI): 0.0017, 0.0477), -100 (β = 0.0264, 95% CI: 0.0087, 0.0441) and Σ₅PBDEs (β = 0.0201, 95% CI: 0.0027, 0.0374). For boys, compared with the lowest exposure groups, statistically significantly higher (feminized) 2D:4D for both hands was observed in those with the highest exposure levels of BDE-100 (β = 0.0147, 95% CI: 0.0005, 0.0289 for the left hand; β = 0.0182, 95% CI: 0.0046, 0.0318 for the right hand) and those with the middle and the highest exposure levels of BDE-153 (middle vs. undetected, β = 0.0215, 95% CI: 0.0072, 0.0358 for the left hand; β = 0.0155, 95% CI: 0.0015, 0.0295 for the right hand; highest vs. undetected, β = 0.0162, 95% CI: 0.0017, 0.0307 for the left hand; β = 0.0152, 95% CI: 0.0011, 0.0294 for the right hand).

CONCLUSIONS

Our study provides preliminary evidence that prenatal exposure to PBDEs might be associated with higher 2D:4D in boys and girls.

Can second to fourth finger ratio play a role in determining the risk of benign prostatic enlargement

Benign prostatic enlargement (BPE) is a disease that testosterone plays a role in its aetiology. Second to fourth finger ratio is a marker of prenatal androgenic exposure and may be a risk factor for several androgen-related diseases such as BPE. In this study, we investigated the relationship between the second to fourth finger ratio and BPE. A total of 63 patients with BPE were included for study group, and age-matched 63 healthy patients were included as a control group. Finger was measured by the distance from the proximal crease to the tip by using a digital caliper. The mean age of patients with BPE and non-BPE was 62 ± 8.9 and 61.5 ± 7.1 years respectively. There was statistically significant difference between groups in terms of prostate-specific antigen levels, prostate volumes and international prostate symptom scores. The mean finger ratios for right and left hand were 0.97 ± 0.03, 0.99 ± 0.03(p = .001) and 0.93 ± 0.15, 0.98 ± 0.03(p < .001) for BPE and non-BPE groups respectively. Men with a lower second to fourth finger ratio have higher risk of developing BPE than men without BPE. Therefore, the second to fourth finger ratio, which is indicative of prenatal androgen exposure, can be used as a marker of BPE risk.

The relationship between anogenital distance and lifelong premature ejaculation

BACKGROUND

Many diseases have been associated with anogenital distance, as an indicator of intrauterine androgen exposure.

OBJECTIVES

The aim of this study was to investigate the association between lifelong premature ejaculation and anogenital distance.

MATERIALS AND METHODS

The study included 140 participants: 70 with lifelong premature ejaculation (group 1) and 70 without any ejaculatory complaints (group 2). Premature Ejaculation Diagnostic Tool and stopwatch intravaginal ejaculatory latency time were recorded from all participants in order to evaluate ejaculatory function. Two variants of anogenital distance were measured: anogenital distance (from anus to the posterior base of the scrotum) from anus to the posterior base of the scrotum and anogenital distance (from anus to the cephalad insertion of the penis) to the cephalad insertion of the penis. We compared differences between groups and correlations between anogenital distance variants and patients' characteristics.

RESULTS

The groups were similar in terms of age, BMI, and total testosterone levels. The mean anogenital distance (from anus to the posterior base of the scrotum) scores were 59.45 ± 10.76 vs. 55.02 ± 10.13 (p = 0.01), and anogenital distance (from anus to the cephalad insertion of the penis) scores were 128.37 ± 22.2 vs. 126.78 ± 16.21 (p = 0.63) in groups 1 and 2, respectively. Significant correlation was observed between anogenital distance (from anus to the posterior base of the scrotum) and Premature Ejaculation Diagnostic Tool scores (r = 0.199, p = 0.019) and intravaginal ejaculatory latency time (r = -0.185, p = 0.028). There were no statistically significant differences between anogenital distance (from anus to the posterior base of the scrotum) scores and total testosterone levels and between anogenital distance (from anus to the cephalad insertion of the penis) and Premature Ejaculation Diagnostic Tool scores or intravaginal ejaculatory latency time.

CONCLUSIONS

These results suggest that longer anogenital distance is associated with higher possibility of lifelong premature ejaculation. However, further studies are needed to confirm our results.