Premature ejaculation (PE; also known as rapid ejaculation) is the most common type of sexual dysfunction in men younger than 40 years. Most professionals who treat premature ejaculation define this condition as the occurrence of ejaculation prior to the wishes of both sexual partners. This broad definition thus avoids specifying a precise duration for sexual relations and reaching a climax, which is variable and depends on many factors specific to the individuals engaging in intimate relations. An occasional instance of premature ejaculation might not be cause for concern, but, if the problem occurs with more than 50% of attempted sexual relations, a dysfunctional pattern usually exists for which treatment may be appropriate.
To clarify, a male may reach climax after 8 minutes of sexual intercourse, but this is not premature ejaculation if his partner regularly climaxes in 5 minutes and both are satisfied with the timing. Another male might delay his ejaculation for a maximum of 20 minutes, yet he may consider this premature if his partner, even with foreplay, requires 35 minutes of stimulation before reaching climax. If intercourse is the method of sexual stimulation for the second example and the male climaxes after 20 minutes of intercourse and then loses his erection, satisfying his partner (at least with intercourse), who needs 35 minutes to climax, is impossible.
Because many females are unable to reach climax at all with vaginal intercourse (no matter how prolonged), this situation may actually represent delayed orgasm in the female partner rather than premature ejaculation in the male; the problem can be either or both, depending on the point of view. This highlights the importance of obtaining a thorough sexual history from the patient (and preferably from the couple).
The criteria for premature ejaculation stated in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, text revision (DSM-IV-TR) is as follows: (1) persistent and recurrent ejaculation with minimal sexual stimulation before, on, or shortly after penetration before the person wishes it; (2) marked distress or interpersonal difficulty; and (3) not exclusively due to direct effects.
The human sexual response can be divided into 3 phases: desire (libido), excitement (arousal), and orgasm. The Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) classifies sexual disorders into 4 categories: (1) primary, (2) general medical condition–related, (3) substance-induced, and (4) not otherwise specified. Each of the 4 DSM-IV categories has disorders in all 3 sexual phases.
Premature ejaculation may be primary or secondary. Primary premature ejaculation applies to individuals who have had the condition since they became capable of functioning sexually (ie, postpuberty). Secondary premature ejaculation means that the condition began in an individual who previously experienced an acceptable level of ejaculatory control, and, for unknown reasons, he began experiencing premature ejaculation later in life. Secondary premature ejaculation does not relate to a general medical disorder and is usually not related to substance inducement, although, rarely, hyperexcitability might relate to a psychotropic drug and resolves when the drug is withdrawn. Premature ejaculation fits best into the category of “not otherwise specified” because the cause is unknown, although psychological factors are suggested in most cases.
Premature ejaculation is believed to be a psychological problem and does not represent any known organic disease involving the male reproductive tract or any known lesions in the brain or nervous system. The organ systems directly affected by premature ejaculation include the male reproductive tract (ie, penis, prostate, seminal vesicles, testicles, and their appendages), the portions of the central and peripheral nervous system controlling the male reproductive tract, and the reproductive organ systems of the sexual partner (for the purpose of this discussion, the partner is assumed to be female) that may not be stimulated sufficiently to achieve orgasm.
If the premature ejaculation occurs so early that it happens before commencement of sexual intercourse and the couple is attempting pregnancy, then pregnancy is impossible to achieve unless artificial insemination is used. Perhaps the most affected organ system is the psyche of the partners. Both partners are likely to be dissatisfied emotionally and physically by this problem.
From an evolutionary perspective, logic may dictate that males who can ejaculate rapidly would be more likely to succeed in fertilizing a female than males who require prolonged stimulation to reach climax. The genes of a male who ejaculates rapidly (but not so rapidly that ejaculation occurs before intromission) would be more likely to be passed on to succeeding generations. In a primitive sense, a male who could not complete the fertilization process quickly might be pushed away or killed by a competing male because of his obvious vulnerability during intercourse.
Premature ejaculation has historically been considered a psychological disorder. One theory is that males are conditioned by societal pressures to reach climax quickly because of fear of discovery when masturbating as teenagers or during early sexual experiences “in the back seat of the car” or with a prostitute. This pattern of rapid attainment of sexual release is difficult to change in marital or long-term relationships. The fact that female arousal and orgasm require more time than male arousal is being increasingly recognized, and this may result in increased recognition and definition of premature ejaculation as a problem.
Some have questioned whether premature ejaculation is purely psychological. A number of investigators have found differences in nerve conduction/latency times and hormonal differences in men who experience premature ejaculation compared with individuals who do not. The theory is that some men have hyperexcitability or oversensitivity of their genitalia, thus preventing down-regulation of their sympathetic pathways and delay of orgasm. Recently, a certain group of nerves in the lumbar spinal cord has been identified as the possible generator of ejaculation. This nerve site is thought to be linked to excitatory and inhibitory dopamine pathways in the brain, which play significant roles in sexual behavior. This knowledge, while continuing to be researched, is providing the foundation for possible development of medications specifically targeting delay of ejaculation.
Other questions have been raised regarding possible biochemical factors in premature ejaculation. Testosterone is thought to play a role in the ejaculatory reflex. Higher testosterone (free and total) levels have been demonstrated in men with premature ejaculation than in men without premature ejaculation.
Research published in a Chinese andrology journal showed that semen from men with premature ejaculation contained significantly less acid phosphatase and alpha-glucosidase than did the semen of controls. These researchers concluded that these biochemical parameters may reflect dysfunction of the prostate and epididymis, possibly contributing to premature ejaculation; however, these have yet to be supported by subsequent studies.
In other biochemical parameters, many men with premature ejaculation have been shown to have low serum levels of prolactin. However, in this same study of prolactin in men with sexual dysfunction, men in the lowest quartile of serum prolactin levels who had premature ejaculation also demonstrated associated metabolic syndrome, erectile dysfunction, and anxiety. In other words, while biochemical markers such as prolactin may contribute to premature ejaculation, organic and psychological associations (ie, anxiety) suggest that biochemical parameters play only a partial role in premature ejaculation. Further research is needed.