The rapidity of ejaculation in men is genetically determined, according to research by Utrecht University Neuropsychiatrist Dr. Marcel Waldinger and Pharmacological Researcher Paddy Janssen.

The participants in the study by Waldinger and Janssen were 89 Dutch men who suffer from the primary form of premature ejaculation, in other words, men who always had this problem. A control group of 92 men was also studied. For a month the female partners used a stopwatch at home to measure the time until ejaculation each time they had intercourse.

In men who suffer from premature ejaculation, the substance serotonin appears to be less active between the nerves in the section of the brain that controls the ejaculation. Among other things, this substance is linked to sexual activity and appetite. It is a substance that transfers a signal from one neuron to another. Due to the low activity of serotonin, this signal transfer does not occur properly in men with the primary form of premature ejaculation.

"This study applies to men who have always ejaculated prematurely from their first sexual contact onwards and not for men who started suffering from this later on in life," Waldinger emphasises.

Gene, Not Psychology

A gene which had already been discovered, 5-HTTLPR, appears to be responsible for the amount and activity of serotonin, which means that it controls the rapidity of ejaculation. Three types of the gene exist: LL, SL and SS. The study showed that the LL type causes a more rapid ejaculation.

On average, men with LL ejaculate twice as quickly as men with the SS type, and also almost twice as quickly as men with SL. The researchers are currently also looking for other genes that are involved in ejaculation.

Ten years ago, researcher Marcel Waldinger predicted that both the rapidity with which men ejaculate and the primary form of premature ejaculation were genetically determined.

"This theory contradicts the idea, which has been common for years, that the primary form of premature ejaculation is a psychological disorder," explains Waldinger. "The results of our research confirm the genetic theory and may contribute to possible gene therapy against premature ejaculation."

Article: P.K.C. Janssen, M.D. Waldinger and others. Serotonin Transporter Promoter Region (5-HTTLPR) Polymorphism is Associated with the Intravaginal Ejaculation Latency Time in Dutch Men with Lifelong Premature Ejaculation, Journal of Sexual Medicine, October 7, 2008