The association between erectile dysfunction (ED), free testosterone (T), and androgenic genetic polymorphisms is still unclear. As most studies in the field have focused on older (>40 y.o.) men, data from young men is scarce. In addition, the clinically observed comorbidity between ED and premature ejaculation (PE) has not been explained.
The aim of the present study was 3-fold: to assess in a sample of young men (1) the association between ED and T; (2) the role of androgenic genetic polymorphisms in the aforementioned association; and (3) comorbidity between ED and PE symptoms.
Statistical analyses were performed on a population-based sample of 2,302 Finnish men, (Mage = 26.8 years). Hormone samples were available from 317 men, and genotype information was available from a minimum of 1,144 men depending on genetic locus. For twin analyses, the sample contained 533 male individuals from opposite-sex fraternal twin pairs, 491 identical male individuals (110 complete pairs), 493 male individuals from male fraternal twin pairs (92 complete pairs), and 658 siblings of twins.
The main outcome measure includes association between levels of salivary T and ED, main effects of the androgen-related genetic polymorphisms on ED scores. Bivariate twin models of PE and ED were fitted to elucidate possible shared etiology.
We found no significant association between T levels and ED and no significant main effects of the androgenic genetic polymorphisms on ED. We found no evidence suggesting that any of the genetic polymorphisms would moderate the association between T and ED symptoms. We found shared unique environmental influences between PE and ED (rE = .28).
Obtained data suggest that ED has T-independent causes and that any comorbidity between PE and ED is not explained by a set of genes affecting both phenotypes.
First, the sample size for both parts of the study was relatively small, which may make some statistical analyses underpowered. Furthermore, as the sample was a population-based sample of relatively young men, the number of clinically relevant ED cases was low. Second, some concerns about T derived from saliva exist because saliva sampling comes with increased risks of error particularly because saliva samples are more vulnerable to contamination.
We found no significant association between free T levels, androgenic genetic polymorphisms, and ED in the younger age cohort. Twin analysis suggested a common nonshared environmental component in PE and ED. Zhuravleva1 ZD, Johansson A, Jern P. Erectile Dysfunction in Young Men: Testosterone, Androgenic Polymorphisms, and Comorbidity With Premature Ejaculation Symptoms. J Sex Med 2020;XX:XXX-XXX.
The journal of sexual medicine. 2020 Nov 23 [Epub ahead of print]
Zoia D Zhuravleva, Ada Johansson, Patrick Jern
Department of Fundamental and Applied Research, Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, Russia. Electronic address: ., Department of Psychology, Åbo Akademi University, Turku, Finland.