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Premature ejaculation (PE) occurs when a man experiences orgasm and expels semen soon after sexual activity and with minimal penile stimulation. It has also been called ''early ejaculation,'' ''rapid ejaculation,'' ''rapid climax,'' ''premature climax,'' and (historically) ''ejaculatio praecox.'' There is no uniform cut-off defining "premature", but a consensus of experts at the International Society for Sexual Medicine endorsed a definition including "ejaculation which always or nearly always occurs prior to or within about one minute".〔Sharlip, I. D., Hellstrom, W. J., & Broderick, G. A. (2008). The ISSM definition of premature ejaculation: A contemporary, evidence-based definition. ''Journal of Urology, 179''(suppl), 340, abstract 988.〕 The International Classification of Diseases (ICD-10) applies a cut-off of 15 seconds from the beginning of sexual intercourse.〔Althof, S. E. (2007). Treatment of rapid ejaculation: Psychotherapy, pharmacotherapy, and combined therapy (pp. 212–240). In S. R. Leiblum (Ed.), ''Principles and practice of sex therapy'' (4th ed.). NY: Guilford.〕 Although men with premature ejaculation describe feeling that they have less control over ejaculating, it is not clear if that is true, and many or most average men also report that they wish they could last longer. Men's typical ejaculatory latency is approximately 4–8 minutes.〔 Men with PE often report emotional and relationship distress, and some avoid pursuing sexual relationships because of PE-related embarrassment. Compared with men, women consider PE less of a problem, but several studies show that the condition also causes female partners distress. ==Cause== The causes of premature ejaculation are unclear. Many theories have been suggested, including that PE was the result of masturbating quickly during adolescence to avoid being caught by an adult, of performance anxiety, of an unresolved Oedipal conflict, of passive-aggressiveness, and having too little sex; but there is little evidence to support any of these theories.〔Strassberg, D. S., & Perelman, M. A. (2009). Sexual dysfunctions. In P. H. Blaney & T. Millon (Eds.), ''Oxford textbook of psychopathology'' (2nd ed.), (pp. 399–430). NY: Oxford University Press.〕 Several physiological mechanisms have been hypothesized to contribute to causing premature ejaculation including serotonin receptors, a genetic predisposition, elevated penile sensitivity, and nerve conduction atypicalities.〔 The nucleus paragigantocellularis of the brain has been identified as having involvement in ejaculatory control. Scientists have long suspected a genetic link to certain forms of premature ejaculation. In one study, 91 percent of men who have had premature ejaculation for their entire lives also had a first-relative with lifelong premature ejaculation. Other researchers have noted that men who have premature ejaculation have a faster neurological response in the pelvic muscles. PE may be caused by prostatitis〔 or as a drug side effect. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Premature ejaculation」の詳細全文を読む スポンサード リンク
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