Understanding the normal sexual response cycle is being revised.
The phenomenal success of Viagra has prompted research into the differing factors that fuel female sexual function and dysfunction. The new theory suggests that the desire for intimacy and other aspects of the personal relationshiprather than the need for physical sexual releasemay matter most.
Our understanding of the normal sexual response cycle in men and women is being revised. Several factors have fueled this paradigm shift over the last four decades: clinical advances in the field, new technological tools for studying sexual response in the laboratory, and more open discussion and debate of sexual topics in general.
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But more than anything else, the enormous success of sildenafil (Viagra) has prompted the new emphasis on understanding female sexual function and dysfunction. Pharmaceutical companies, sex therapists, and women themselves have begun to wonder: Might the drugs that work so well for men in enhancing sexual arousal benefit women as well? Consequently, researchers are now focusing more on understanding female sexual response in general, and on uncovering the specific factors that spark sexual desire and arousal in women. From this scrutiny has emerged an awareness that female sexual response is driven and perhaps maintained by factors that are quite different from those characteristic of males.
Our purpose here is to provide a brief overview of these changing concepts and to highlight the most current views of what constitutes normal sexual response in women. We will review the new consensus-based definitions of female sexual dysfunction, as well as areas of female sexual response that are still incompletely understood.
Perhaps Sigmund Freud first articulated the notion of sexual response as a sequence of related eventsany of which may potentially create sexual difficulties.1 As long ago as 1926, he wrote "the execution of the sex act presupposes a very complicated sequence of events, any one of which may be the locus of disturbance." He went on to describe the problems that might develop, referring primarily to disorders of male sexual functionsuch as erection and ejaculatory difficulties. He did note, however, that problems of libido might arise in men, referring to "the turning aside of the libido at the initiation of the act." Long before it became commonly accepted knowledge, Freud recognized that problems relating to sexual desire could interfere with or short-circuit the entire sexual response cycle.
After Freud came the sexual response cycle described by Masters and Johnson in 1966 in their volume, Human Sexual Response, which is the model familiar to most practitioners.2 It identified four distinct phases of sexual response: excitement, plateau, orgasm, and resolution. These four phases were believed to occur in a linear, fairly invariant fashion for both men and women. Although Masters and Johnson acknowledged that not all women consistently reach orgasm or experience all four phases of the cycle, they believed that, basically, the model mirrored fairly well both the male and female experience of engaging in sex.
Excitement. Essentially, Masters and Johnson said that with the onset of any sexual stimuluswhether internal, such as sexual tingling, or external, such as sensual touching or visual imagesindividuals promptly experience physiological arousal. Arousal is experienced as erection in the male or vasocongestion and myotonia (muscle tension) in the female.
Plateau and orgasm phases. If sexual stimulation continues uninterrupted, men and women would experience greater levels of sexual tension, resulting in what Masters and Johnson termed plateau levels of sexual excitement. Additional stimulation would then culminate in ejaculation and orgasm in the man and orgasm in the woman.
Resolution. According to this model, following ejaculation, men would experience a necessary resolution or refractory period, during which blood levels returned to normal and further stimulation would not result in an erection. In women, the refractory period was more flexible and shorter, so that additional stimulation after the first orgasm might quickly result in a second or even multiple orgasms.
So influential was their model that it became the basis for the diagnosis and classification of sexual dysfunction in both the 1980 and 1987 Diagnostic and Statistical Manual of Mental Disorders (DSM-III, 1980 and DSM-III-R, 1987).3,4
An important omission in the Masters and Johnson model of sexual response, however, became evident soon after the 1970 publication of their second landmark volume, Human Sexual Inadequacy.5 Clinicians began to notice that some of their patients did not present with the typical problems of sexual performance, that is, difficulty becoming aroused or reaching orgasm. Rather, these individuals, although perfectly capable physically of responding sexually, had little inclination to do so. It soon became evident that Masters and Johnson had neglected one of the most important aspects of sexual behavior, namely sexual desire. Without desire, there seemed to be little inclination to participate in sexual activity and whatever arousal existed could easily be extinguished.
It is of interest that today, problems and conflicts revolving around sexual motivationlow sexual interest, incompatible levels of sexual desire between partners, and even excessively high sexual desireare the most common problems seen in sex counseling. For both women and men, hypoactive sexual interest is an exceedingly prevalent concern.
There were other problems, too, with the Masters and Johnson model of sexual response. The four-phase model reflected a heterosexual, phallocentric view of sexual behavior, with the underlying implication that intercourse and orgasm were the natural end points of sexual interaction. An attempt to create a politically correct modelone that accurately mirrored the physical and subjective experience of both men and women without prejudicing one or the otherfailed to do so. For instance, while arousal in a man was easy to identify, female arousal was not. Lubrication was not a reliable hallmark of sexual arousal since some women lubricated copiously, without feelings of subjective excitement, while others were aware of little or no lubrication but felt aroused.
Another flaw in the Masters and Johnson four-stage sexual response cycle was that it suggested that sexual response unfolded in a clear-cut linear sequence of excitement, plateau, orgasm, and resolution when, in fact, a more circular model seems appropriate, with each phase affecting and reinforcing the preceding stage. Moreover, the plateau phase was difficult to document and did not add much to the description of sexual response.
Finally, the model overemphasized physiological genital responsivity. There was a notable failure to identify or recognize the emotional and interpersonal elements involved in sexual responsethose that for most women were the more salient aspects of the sexual experience. Studies looking at overall satisfaction indicate that, for women, the nongenital aspects of the sexual encounterthe amount of intangible interpersonal elements like closeness, intimacy, and sensualitywere more important determinants of satisfaction than were the presence or absence of orgasm. Sexual response is clearly a complicated biopsychosocial phenomenon with both biological and psychological contributions.
In 1977, Helen Singer Kaplan proposed an alternative model that highlighted the aspects of sexual response she regarded as most relevant.6 Rather than a four-phase model, she proposed a triphasic approach, with desire given first place, reflecting its importance in triggering the entire cycle. The Kaplan model conceived of normal sexual response as consisting of desire, arousal, and orgasm.
The model remained inadequate, however, even with this important modification. For one thing, it did not seem to reflect women's experience. Many women never experience spontaneous desire and for those who do, it does not always lead to sexual initiation or arousal. In fact, most women rely on their male partner to make the initial sexual overture, to which they might either acquiesce or not, depending on a number of both physical and nonsexual factors.
Furthermore, for many men and women, arousal precedes desire. The discovery of an erection or the awareness of pleasurable genital sensations whets their sexual interest, thereby igniting sexual desire. In other words, desire seemed to follow arousal, not the other way around. In addition, the model said nothing about the feeling of sexual satisfaction. Did the experience of arousal and orgasm lead to a sense of sexual pleasure and gratification? Without some understanding of the subjective feelings associated with the sexual response cycle, much information is lost.
In 1999, a psychiatrist named Rosemary Basson was the first to fully articulate the ways in which the Kaplan model failed to reflect women's actual experiences.7 While it is true that for many men, sexual desire leads to arousal, culminating in orgasm and resolution, for most women, arousal and desire are quite interchangeable. Many women are slow to feel sexually aroused, and it is only with arousal that their subjective feelings of sexual interest are kindled. Still other women experience high levels of arousalperhaps lasting for many minutesbut do not go on to experience orgasm. For some women there is no definite peak of arousal and furthermore, they need not always experience orgasm to feel sexually satisfied. And some women experience multiple orgasms in quick succession without needing to "begin" the cycle over again at the so-called initial "desire" phase.
More significantly, earlier this year, Basson postulated that for many women, it is the desire for intimacy rather than for physical sexual release per se that serves as the starting point of the sexual response cycle (Figure 1).8 She noted that many women have no strong innate biological drive to be sexualnothing nearly as strong as their biological drive to care for and protect their children. Rather, for the women she studied, it was the wish to connect intimately with a partner for a variety of positive reasons (or the avoidance of negative consequences) that caused them to be receptive to sexual stimulation or to seek it out.
According to Basson, even a woman with low internal feelings of desire might seek out sexual contact with her partner because she worries that he has become overly distant or petulant and unhappy when there has been too long an interval without sexual intimacy. Or a woman might want to experience the improved climate of warmth and intimacy following a mutually gratifying sexual encounter, although she has no conscious awareness of needing sexual release herself.
In fact, either internal or external stimuli might motivate the woman to be receptive or willing to become sexually aroused. A woman's appetite might be whetted either by the classical sexual stimulantssuch as visual or auditory erotic stimulior by the more subtle reactions of a partner finding her attractive, desirable, important, and treasured. Regardless of the source of the motivation, the Basson model postulates that many women make a conscious decision to become aroused. This decision then leads to arousal, which then triggers sexual desire. As effective stimulation continues, the arousal may build. The cycle may or may not culminate in orgasm, but if it results in satisfaction for the woman (and her partner), the cycle is likely to be repeated. If it results in satisfaction only rarely, then a woman is unlikely to seek it.
Clinicians should note several important points about this concept of sexual response: First, Basson postulates that arousal and desire are fairly interchangeable for womenwith one stimulating and providing positive feedback for the other. And in fact, many women cannot separate the experience of desire from the experience of sexual arousal.
Secondly, nonsexual interpersonal factors are extremely important in determining whether a woman will be sexually motivated. If she is angry at or resentful towards a partner, for instance, what would otherwise be effective sexual stimulisuch as erotic films, sensual caresses, or sweet wordsmay be totally ineffective in precipitating sexual arousal. This holds true as well if she fears sexual arousal because of earlier abusive or coercive experiences. In other words, the woman may be physiologically capable of becoming aroused but psychologically disinterested or unmotivated.
Thirdly, the model is viewed as a circular one, with each phase stimulating and being stimulated by the preceding one. Rather than envisioning an orderly, linear progression of desire, arousal, and orgasm, Basson and others believe that the sexual response cycle is more accurately understood as consisting of both sexual and nonsexual elements that affect each phase.9
Finally, the sexual response cycle should include some reference to its endpointeither feelings of satisfaction or feelings of disappointment and frustrationif it is to be a meaningful picture of what transpires during a sexual encounter. To illustrate the importance of subjective pleasure or satisfaction as a key aspect of the sexual response cycle, Lief, in the 1980s, suggested the DAVOS cycle, that is, Desire, Arousal (psychological), Vasocongestion (physiological arousal: erection in men; lubrication in women), Orgasm, and most importantly, Satisfaction.10
In fact, there are both women and men who can go through the physiological changes associated with the sexual response cycle without experiencing much pleasure. It is for this reason that it is so important to question patients about their subjective experiences during and after sexual activity, as well as their objective, physiological, or genital response.
Along with changing notions of "normal sexual response," there have been recommendations for changes in the diagnosis of female sexual dysfunction. Recently the Sexual Function Health Council of the American Foundation for Urologic Disease (AFUD) convened a consensus conference to review and update the current classification of female sexual disorders.11 At that meeting, an interdisciplinary and international group of sex therapists, researchers, and physicians knowledgeable about female sexuality was assembled to review and refine each diagnosis. Proposed changes were agreed upon via the Rand method of establishing consensus.
Although imperfect, the four major categories of dysfunctiondesire disorders, arousal disorders, orgasmic disorders, and sexual pain disorderswere retained in order to preserve continuity with previous clinical and research practice. However, the group altered each diagnosis definition to include assessment of the subjective experience, namely whether or not the woman experienced personal distress with regard to the problem (see "AFUD Consensus Panel classifications of female sexual dysfunction," below, for definitions).
This classification system was created by the Consensus Panel convened by the American Foundation for Urologic Disease (AFUD) in 1998. It is based on Kaplans three-phase refinement (desire, arousal, orgasm) of Masters and Johnsons original four-phase model (excitement, plateau, orgasm, and resolution) of female sexual response.
I. Sexual desire disorders.These consist of two disorders:
Hypoactive sexual desire disorder (HSDD). This disorder is defined as the persistent or recurrent deficiency (or absence) of sexual fantasies, and/or desire for, or receptivity to, sexual activity, which causes personal distress. Emphasis is on the persistent (rather than intermittent) lack of usual markers of desiresuch as sexual thoughts or fantasies and/or receptivity to initiation by a partner. Some of the women in this category have Sexual aversion disorder (SAD), defined as the persistent or recurrent phobic aversion to and avoidance of sexual contact with a sexual partner, which causes personal distress.
II. Female sexual arousal disorder (FSAD). Although the hardest disorder to precisely define (see text), FSAD is described as: the persistent or recurrent inability to attain or maintain sufficient sexual excitement, causing personal distress. It may be expressed as a lack of subjective excitement, or a lack of genital lubrication/swelling, or other somatic response.
III. Female orgasmic disorder.This disorder is defined as the persistent or recurrent difficulty, delay in, or absence of attaining orgasm following sufficient sexual stimulation and arousal, which causes personal distress.
IV. Sexual pain disorders.Three are now recognized.
All four classifications (I-IV) above are subtyped as (A) lifelong versus acquired; (B) generalized versus situational; and (C) etiologic origin (organic, psychogenic, mixed, unknown).
Sexual disease disorders. The first of the two sexual desire disorders in this category, hypoactive sexual desire disorder (HSDD), is described in the classification table and needs no further comment here. In defining the second onesexual aversion disorder (SAD)the panel placed the emphasis on its phobic nature. Although discussion centered on whether SAD might better be classified as a phobia and removed from inclusion in the female sexual dysfunctions, the group decided to maintain this classification for the present.12
Female sexual arousal disorder (FSAD). The second of the major categories of dysfunctions proved to be the most difficult to define. FSAD continues to elude a precise definition that is useful to either researchers or clinicians. In the past, FSAD was rarely diagnosed independently of desire and/or orgasmic disorders.
Given the new interest in pharmacologic preparations that enhance male erectile response, determining their potential effectiveness in women has become increasingly important. Whereas in men, erection is a clear-cut indicator of arousal, a lack of arousal is difficult to identify in women, given that lubrication is not a reliable index of subjective sexual arousal. For example, some women even become lubricated during a sexual assault, while other women report psychological arousal in the absence of lubrication (as with estrogen deficiency). The consensus group acknowledged that there is also a genuine question about whether desire and arousal can or should be classified separately.
The most important aspect of the definition of FSAD (Classification II) is the lack of subjective excitement, since most women are unaware of whether they are experiencing genital lubrication or swelling. Also there is a weak correlation between subjective arousal and physiologic arousal. In the absence of subjective excitement, most women do not care if they lubricate or not. In fact, pilot data on a new female sexual function scale, The Female Sexual Function Inventory, suggest that many women exist who, while they perhaps meet the old diagnosis of FSAD, report little personal distress and therefore would not be diagnosed according to the new definition.13
Female orgasmic disorder (III). The panel's emphasis in defining this third dysfunction was on ensuring that the definition included "sufficient sexual stimulation" and arousal. A woman would be insufficiently stimulated, for example, if her partner has erectile or ejaculatory problems and therefore cannot achieve orgasm. Moreover, to warrant diagnosis, the anorgasmia must cause personal distress to the woman herself, whether her partner is concerned about it or not.
Sexual pain disorders. The sexual pain disorders classification (IV) was expanded to include a third noncoital sexual pain category because a significant number of women experience pain during noncoital stimulation but do not meet the criteria for diagnosis of either vaginismus or dyspareunia.
Finally, as noted in the sidebar, each of the four classifications are subtyped in three ways. The panel expanded the "etiology" subtype to include an "unknown" category. In doing so, the group was acknowledging the fact that clinicians often do not know what caused the sexual problem. To stimulate research, they felt it important to admit that the etiology of the complaint is unknown whenever that is the case, rather than guess or label the disorder as "mixed" (which would suggest both psychological and physical determinants).
Many aspects of sexual response are still not fully understood. For instance, we have recently encountered several women who complain of persistent sexual arousal without any feelings of conscious desire.14 We have termed this condition persistent sexual arousal syndrome and describe it as consisting of five distinct features:
To date, the psychological and pathophysiological causes of this syndrome are unknown, although it does not appear to be related to any readily diagnosed hormonal, vascular, or neurological anomalies (for example, high levels of testosterone or neurological lesions).
We do not know why some women are so readily orgasmic while others require many minutes of concentrated stimulation. Similarly, we do not have any hard data on the prevalence of female ejaculation, the emission of fluid, not urine, accompanying orgasm.
Much remains to be understood about female sexual pain disorders as well. For instance, vulvar vestibulitisa subtype of vulvodynia that is extremely painful and quite prevalent among womenremains poorly understood in terms of etiology and treatment.
Researchers are paying more attention to female sexuality for two reasons: It is now recognized that many women experience sexual disinterest or have other complaints and second, several interested parties want to find pharmacologic interventions that will increase women's sexual pleasure.
But more work remains to be done. Fortunately, Basson's proposed concept of the sexual response cycle is a new positive step in this direction because it highlights the essential role that nonsexual considerations like the wish for increased intimacy and interpersonal harmony play in motivating and maintaining much of a woman's sexual behavior.
1. Freud S. The Problem of Anxiety. New York: The Psychoanalytical Quarterly Press and WW Norton & Co, Inc. 1936. (Original work published 1926).
2. Masters WH, Johnson VE. Human Sexual Response. Boston, Mass: Little, Brown; 1966.
3. Diagnostic and Statistical Manual of Mental Disorders (DSM-III). 3rd ed. Washington, DC: American Psychiatric Association; 1980.
4. Diagnostic and Statistical Manual of Mental Disorders (DSM-III-R). 3rd rev. Washington, DC: American Psychiatric Association; 1987.
5. Masters WH, Johnson VE. Human Sexual Inadequacy. Boston, Mass: Little, Brown; 1970.
6. Kaplan HS. Disorders of Sexual Desire and Other New Concepts and Techniques in Sex Therapy. New York, NY: Brunner/Mazel Publications; 1979.
7. Basson R. An alternative sexual response cycle in women and its use in the assessment and management of low sexual desire. Presented at: The Female Sexual Dysfunction Conference; October 16, 1999; Boston, Mass.
8. Basson R. The female sexual response: a different model. J Sex Marital Ther. 2000;26:51-65.
9. Leiblum SR. Definition and classification of female sexual disorders. Int J Impot Res. 1998;10:S102-S106.
10. Lief H. Evaluation of inhibited sexual desire: relationship aspects. In: Kaplan HS, ed. Comprehensive Evaluation of Disorders of Sexual Desire. Washington, DC: American Psychiatric Press; 1985:59-76.
11. Basson R, Berman J, Burnett A, et al. Report of the International Consensus Development Conference on Female Sexual Dysfunction: definitions and classifications. J Urol. 2000;163:888-893.
12. Leiblum SR. Critical overview of the new consensus-based definitions and classification of female sexual dysfunction. J Sex Marital Ther. In press.
13. Rosen R, Brown C, Heiman J, Leiblum SR, et al. The Female Sexual Function Index (FSFI): A multidimensional self-reports instrument for the assessment of female sexual function. J Sex Marital Ther. 2000;26:191-208.
14. Leiblum SR, Nathan S. Persistent sexual arousal syndrome: an unexplored aspect of female sexual response. J Sex Marital Ther. Paper submitted for publication.
For practical advice from a urologist's perspective on treating or referring a patient with sexual dysfunction, see "Female sexual dysfunction: what is known and what can be done." Contemporary OB/GYN. February 2000;45:25-46 or access it on our Web site: www.contemporaryobgyn.net . See also "Female sexual dysfunction: New frontiers in diagnosis and therapy," in our sister publication, Contemporary Urology. June 2000;12:55-60.
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Sandra Leiblum. CME: Redefining female sexual response.