Lifelong premature ejaculation: current debate on definition and treatment

Evidence for a genetic etiology to ejaculatory dysfunction

A number of theoretical approaches to understanding the etiology of ejaculatory dysfunction have been proposed, but no study has yet found conclusive evidence that premature (PE) or delayed (DE) ejaculation is under genetic control. We conducted twin model fitting analyses on different indicator variables of ejaculatory function on a population-based sample of 3946 twins and their siblings (age 18-48; mean=29.9 years) to investigate genetic, shared environmental and unique environmental effects on PE and DE. A significant moderate genetic effect (28%) was found for PE. No clear-cut familial effect could be detected for DE. Significant associations between ejaculatory function and age were detected, but effects of age were generally very weak. The findings from the present study provide useful information regarding the etiology and understanding of ejaculatory dysfunction.

Premature and delayed ejaculation: genetic and environmental effects in a population-based sample of Finnish twins

INTRODUCTION

A number of different theoretical approaches to understanding the etiology of ejaculatory dysfunction have been proposed, but no behavior genetic study has yet, to our knowledge, been conducted to explore the genetic and environmental influences on ejaculatory dysfunction.

AIM

The aim of the present study was to explore the genetic and environmental effects on premature (PE) and delayed (DE) ejaculation in a population-based sample.

METHODS

The genetic and environmental influences on PE and DE were investigated in a population-based sample of 1,196 Finnish male twins, age 33-43 years, with 91 identical and 110 complete twin pairs. Several different aspects of ejaculatory function were measured by a self-report questionnaire (e.g., latency time, subjective experience of ejaculatory control). Factor analyses distinguished two subcomponents of ejaculatory function, and subsequently, composite variables measuring PE and DE were created. Structural equation modeling was performed on the composite variables.

MAIN OUTCOME MEASURES

Measurement of genetic and environmental effects on PE and DE.

RESULTS

The results suggested moderate genetic influence (28%) on PE, but not on DE (0%). There was a moderate familial effect on DE with shared environmental effects accounting for 24% of the variance. However, omission of the shared environmental component did not directly result in a significantly decreased model fit for DE, and omission of the additive genetic component did not directly result in a significantly decreased fit for the PE model.

CONCLUSIONS

The findings from the present study provide useful information regarding the etiology and understanding of ejaculatory dysfunction.

Premature Ejaculation

Premature ejaculation (PE) is a frequent male sexual complaint that is mediated mainly by disturbances of serotonergic neurotransmission and certain serotonin (5-HT) receptors and, to a lesser extent, oxytocinergic neurotransmission in the CNS. The current Diagnostic Manual of Mental Disorders (fourth edition, revised text) [DSM-IV-TR] definition of PE has a low positive predictive value and is inadequate for clinical, epidemiological and drug treatment research. Categorisation of PE into four well defined syndromes has recently been proposed for the pending DSM (fifth edition) definition of PE. Over the last decade, an increasing number of studies of drug treatment of PE have been published. A meta-analysis of those studies, conducted in accordance with current standards of evidence-based medicine, demonstrated similar efficacies for daily treatment with the serotonergic antidepressants paroxetine hemihydrate, clomipramine, sertraline and fluoxetine, with paroxetine (hydrochloride) hemihydrate exerting the strongest effect on ejaculation. On the basis of fundamental insights into serotonergic neurotransmission, it has been suggested that on-demand selective serotonin reuptake inhibitor (SSRI) treatment will not lead to similarly impressive delays in ejaculation as has been observed with daily SSRI treatment. Indeed, some on-demand studies with SSRIs and studies with the new SSRI dapoxetine have shown a weak ejaculation-delaying effect after 1-2 hours of drug intake. Apart from daily treatment with SSRIs, PE can be delayed by on-demand use of topical anaesthetics and tramadol. Treatment with phosphodiesterase type 5 inhibitors should not be prescribed to men with PE with normal erectile function, but may be used if PE is accompanied by erectile difficulties. There is no scientific support for treatment of PE with intracavernous injection of vasoactive drugs. Animal studies have shown that strong immediate ejaculation delay may be induced by administration of a combination of an SSRI with a serotonin 5-HT(1A) receptor antagonist. The combination of an SSRI and any other compound that immediately and potently raises serotonin neurotransmission and/or use of oxytocin receptor antagonists may form the basis for the development of new on-demand and/or daily drugs for the treatment of PE.

Changing paradigms from a historical DSM-III and DSM-IV view toward an evidence-based definition of premature ejaculation. Part II--proposals for DSM-V and ICD-11

BACKGROUND

In the Diagnostic and Statistical Manual of Mental Disorders (DSM), a descriptive definition for premature ejaculation (PE) that was based on historical assumptions has been accepted.

AIM

To formulate a new functional definition of PE in the DSM.

METHODS

A "syndrome" approach instead of a "complaint" approach is applied and evidence-based data from epidemiological and clinical studies are used.

RESULTS

A new functional definition of PE should pertain to a cluster of "symptoms" of a distinct "syndrome." A syndrome rather than a descriptive definition should distinguish Lifelong and Acquired PE variants. Evidence-based data also suggest another PE type "Natural Variable PE," which is not a typical syndrome but rather a cluster of inconsistent symptoms of rapid ejaculation. Moreover, in "Natural Variable PE" the occurrence of rapid ejaculation is not based on neurobiological or psychological pathology, but belongs to the normal variability of sexual performance. Its prevalence is probably much higher than that of Lifelong and Acquired PE. We propose three separate operationalized definitions of these three PE types for the pending DSM-V and ICD-11, which include a quantification of the ejaculation time (intravaginal ejaculation latency time), inability of ejaculatory control, and a description of severity of PE in terms of psychological distress.

CONCLUSION

The use of the intravaginal ejaculation latency time into the DSM-V and ICD-11 would mean that statistical evidence becomes accepted as one of the mainstays for establishing an evidence-based definition of the three PE types.

Emerging drugs for premature ejaculation

Lifelong premature ejaculation (PE) is a frequent male sexual dysfunction and is thought to be mediated in part by disturbances of serotonergic (5-hydroxytryptamine; 5-HT) neurotransmission and ejaculation-mediating 5-HT receptors in the CNS. The aetiology of the dysfunction is unclear, but probably includes neurobiological and environmental factors. Lifelong PE is a syndrome characterised by a cluster of symptoms. Rapid ejaculations become manifest around the first sexual encounters in puberty or adolescence. Intravaginal ejaculation latency time usually occurs within 30-60 s, or maximally within 2 min after vaginal penetration, is present with nearly every sexual partner, and remains similar throughout life or may aggravate during ageing. The syndrome may lead to secondary psychological, sexual and relationship problems. Daily treatment with some selective serotonin re-uptake inhibitors (SSRIs) leads to strong ejaculation delay, but may be accompanied by side effects. New treatment with SSRIs with a short half-life (if approved) for on-demand use 1-2 h prior to coitus exerts less ejaculation-delaying effects than daily SSRI strategies. Animal studies have shown that strong, immediate ejaculation delay may be induced by the combination of an SSRI with a 5-HT(1A) receptor antagonist. The combination of an SSRI and any other compound that immediately strongly raises 5-HT neurotransmission may form the basis for the development of new on-demand drugs to treat PE.