Linda J Rosen, Raymond C Rosen
Research and theory in female sexual dysfunction are evolving rapidly. New theories and conceptualizations of the field are being developed in the urgent attempt to keep up with the rapid flow of new knowledge and theory, but many questions and controversies remain unresolved. Despite advances in and increasing attention to the topic of female sexual dysfunction, there are still fundamental disagreements concerning the definition and classification of female sexual dysfunction and the proper perspective on treatment. This introductory chapter addresses these issues primarily from an historical perspective, detailing the specific contributions of pioneering sex researchers and therapists, including Alfred Kinsey, William Masters and Virginia Johnson, Helen Singer Kaplan, John Bancroft, and others. In reviewing their broader and individual contributions, we will consider also the emergence of key themes and topics in the field.
In recent decades there have been major advances in our understanding of sexual psychophysiology and pharmacology, and the role of sex steroid hormones, and a growing awareness of cultural factors affecting sexuality. Looking back 50 years, we are aware of rapid and steady growth of knowledge about normative sexual behavior in women (and men), and the evolution of current definitions of normal and “problematic” sexual function in women. However, certain core issues, such as the role of
relationship and interpersonal factors in determining sexual dysfunction, remain relatively unexplored. Biologic factors have undoubtedly received greater attention in the overall field of sexual dysfunction research in the past two decades. This has not been true historically, however, as this chapter will illustrate.
The overall purpose of this chapter is to identify and comment on evolving concepts of female sexual dysfunction. While the chapter proceeds chronologically, several themes and concepts will interweave and inform the discussion:
• Important historical changes have influenced medical and scientific conceptions of female sexuality. The past 50 years has witnessed the sexual revolution of the 1960s and 1970s (paralleled by the widespread use of the birth control pill and other effective forms of contraception), the growth of the pharmaceutic industry, and the development of both prescription and nonprescription products that affect sexual function.
• There is greater understanding of variations in female sexuality between and within different cultural groups. This context-dependent view of female sexuality predates Kinsey, although his work contributed greatly to recognition of the importance of social factors in sexual behavior. The debate on the relative influences of culture and society on female sexuality, compared with biologic and intrapsychic factors, continues unabated to this day.
• In the past decade there have been significant developments in medical, biologic, and pharmacologic approaches to sexuality. This has been described as the “medicalization” of sexuality by those who take issue with the emphasis on pharmaceutic or medical solutions to sexual problems, while some view these new and potentially effective medical treatments to age-old problems in women as presenting new and significant professional challenges. This is a highly controversial and complex area with significant implications for our understanding of female sexual function and dysfunction.
• Changing views of female sexuality have been paralleled, and perhaps influenced by, changes in research methodologies. From Kinsey’s original interview techniques and Masters and Johnson’s direct observation of human sexual response, research has expanded greatly in recent years to incorporate new methods for investigating brain physiology, hormonal changes, and genital blood flow during sexual response. New quantitative and qualitative research methods and survey approaches have also been developed.1,2
• Beginning with Masters and Johnson’s four-phase conceptualization of sexual response, models of normative sexual function have undergone several significant transformations. Recent advances include the emergence of nonlinear models of sexual response in women (e.g., Basson3). These models have served as the basis of proposed diagnostic classifications and management recommendations for female sexual dysfunction.
• The terminology and diagnostic classification of sexual difficulties in women have evolved markedly from earlier value-laden and pejorative terms in the 1950s, such as “frigidity” and “nymphomania”, to more descriptive and scientifically objective terms, such as “female sexual arousal disorder” and “hypoactive sexual desire disorder”. This terminological and conceptual shift began with Kinsey, and continues to the present day.
Today, more than five decades since the publication of Sexual Behavior in the Human Male4 and Sexual Behavior in the Human Female,5 Alfred Kinsey’s research remains among the most reliable sources of information about sexual behavior in America. It is not uncommon for present-day researchers to use Kinsey’s data as a yardstick for measuring change. Kinsey was the researcher who brought sex research, and views of female sexuality in particular, from the last vestiges of the Victorian era into the modern age. In addition to its effects on the scientific community, Kinsey’s groundbreaking studies brought human sexuality fully into the public consciousness.
Alfred Charles Kinsey was born in Hoboken, New Jersey, in 1894; he was a sickly child brought up in a strongly religious household who developed a passion for the outdoors and nature, and rejected religion. He studied biology at Bowdoin College, and pursued doctoral studies at Harvard, where he was an instructor in biology and zoology. His interest in the collection and taxonomy of gall wasps began at this time, and there are noted parallels between this early interest in taxonomy and his later collection of thousands of individual sex histories and categorization of sexual behavior. In 1920, Kinsey became an assistant professor at Indiana University, where he pursued his interest in gall wasp taxonomy for nearly 20 years. It was in the summer of 1938 that Kinsey began to teach a marriage course, which grew in popularity and brought students to Kinsey with questions about their sexuality. The Institute for Sex Research (still functioning at Indiana University in Bloomington) grew out of Kinsey’s efforts to answer students’ questions by accumulating information about sexual behavior.
Kinsey’s taxonomic approach is well known: he is thought to have studied human sexuality in much the same way that a biologist might study the sex lives of any other animal - categorizing sexual behavior in an objective fashion and making no value judgments about this behavior. Indeed, Kinsey may have cultivated the impression that his work was purely empirical because he assumed that this would be more acceptable to the public. However, a closer reading of his books shows that Kinsey often had strong opinions about human sexuality. Kinsey’s sexual “ideology” might be said to include an insistence on tolerance of the enormous variability of sexual activity, and his emphasis on naturalism.6 Kinsey believed that many sexual problems resulted from social training that went against the natural sexual tendencies of other mammals.
Sexual Behavior in the Human Female was published in 1953 amidst a storm of public and scientific controversy. Kinsey removed female sexuality from the realm of moralism and examined it scientifically. While his work on male sexuality was greeted with some shock, the female volume produced outrage. Instead of the Victorian view that masturbation in females was unhealthy and dangerous, Kinsey reported a consistent relationship between premarital masturbation and orgasm during marital intercourse. Among the volume’s most significant conclusions, however, was the great similarity between sexual behavior in males and females. Kinsey emphasized the essential similarity in anatomic structures essential to sexual response and orgasm, and wrote that “males would be better prepared to understand females, and females to understand males, if they realized that they were alike in their basic anatomy and physiology.” While he emphasized the similarity in anatomy and physiology, Kinsey did recognize the influence of hormonal factors on levels of sexual response, although he rejected the idea that hormones affect the types of sexual activity engaged in. Kinsey also rejected the prevailing wisdom, based on psychoanalytic concepts, that masturbation interfered with the development of “vaginal orgasms”, which were a sign of sexual maturity in women. Instead, he observed that the vagina had few nerve endings in most women, and that the clitoris and labia were the major sources of female sexual sensation. In a chapter on the physiology of sexual response and orgasm, Kinsey concluded that orgasm was essentially the same in males and females, and rejected the common notion that females are slower in their capacity to reach orgasm.
Kinsey’s influence on our current understanding of female sexual dysfunction can be illustrated by his discussion of “female frigidity”. On the basis of the nearly 5000 “sex histories” contributed by women to the Kinsey project, he concluded that frigidity - defined as the absence of orgasm - was relatively rare, with 9 of 10 women reporting having experienced orgasm by age 35. An additional 8% reported experiencing arousal without orgasm. Kinsey concluded that essentially all women were physiologically capable of arousal and orgasm. However, he did discover wide variations in female sexual behavior; the age of first orgasm ranged from 9% by 11 years of age to 50% by age 20. More than two out of three women experienced their first orgasm before marriage. There were also great variations in the nature of stimulation leading to the first orgasm, with masturbation the stimulus for 40%, and heterosexual petting the stimulus for about one in four women. Only 17% of women reported having their first orgasm during marital intercourse.
Women also varied in the frequency of orgasm, in the methods used most often to reach orgasm, and in the proportion of sexual encounters that culminate in orgasm. In Kinsey’s statistical portrait of sexual behavior, the average husband starts marriage having already experienced 1523 orgasms, compared with the average wife’s 223 premarital orgasms. Women are also less likely to achieve orgasm during marital sex, and have more variability in their sexual response than men do. Women reported that they were less likely to make use of sexual outlets such as masturbation and nocturnal sex dreams, had fewer sexual fantasies, and experienced less arousal from visual stimulation than men. From this evidence, Kinsey concluded that females were not as sensitive to psychologic influences. This point of view is not accepted today, when sex differences in arousal are more likely to be attributed to social learning.
Kinsey examined the question of why some women were much more likely than others to experience orgasm regularly. He found that education was not a very significant factor, neither was social status (as measured by the father’s occupation). Women born in the 1920s were more likely to experience orgasm regularly than women born in the 1890s, but this effect was also small. The best predictor of marital orgasm for women was their premarital experience - orgasm through masturbation, “petting”, or intercourse before marriage was correlated with greater orgasmic responsiveness during marital intercourse. The problem of “frigidity”, then, was not really a sexual dysfunction so much as a result of the fact that women more easily reach orgasm during masturbation than during intercourse. According to Kinsey, “frigidity” results from the repression of female sexual responsiveness, especially the occurrence of masturbation among girls and young women.
In his conclusion to Sexual Behavior in the Human Female, Kinsey considered the reasons for the male/female differences in psychosexual response that he had reported. In this discussion, Kinsey discredited the notion that hormonal factors produced these gender differences. He distrusted endocrinologic explanations of sexual differences, and cautioned against “overenthusiastic advertising by some of the drug companies” and journalistic accounts of scientific research that lead people to believe that sexual behavior could be controlled though hormonal manipulation. These are controversial and timely comments today.
Kinsey was the first great modernizer in the field of human sexuality, recognizing the potential of women to be sexual creatures, and documenting the multiple variations in female sexual activity. His contributions to our understanding of female sexuality are monumental and lasting.
Masters and Johnson
The publication of Human Sexual Response7 and Human Sexual Inadequacy8 was the next milestone in the history of sex research. The two authors of these volumes, William Masters and Virginia Johnson, advanced the work begun by Kinsey in several ways. The first volume provided an extensive and detailed portrait of how the male and female body responds to sexual stimulation. The information upon which it was based was collected in a little more than a decade, and was derived from direct laboratory observation of more than 10 000 male and female orgasms. The second volume was a similarly extensive description of the causes of sexual “inadequacy”, as well as a presentation of therapeutic techniques to be used to overcome sexual dysfunction in both sexes.
William Masters was born in Cleveland, Ohio, in 1915 and studied medicine at the University of Rochester with a view to establishing a career in research. Masters trained in obstetrics and gynecology, and in addition to his medical practice, he published research on a variety of related topics, including a series of papers on hormone replacement. Like Kinsey, he felt hampered by a lack of reliable information to provide to his patients. Although Masters was certainly not the first scientist to study human sexual response directly, his research on this topic was the most extensive and detailed at this time. Virginia Johnson, born in Missouri in 1925 and with a background in psychology and sociology, joined Masters’ project initially as a research assistant and interviewer. Beginning with a population of prostitutes in the St Louis area, Masters conducted interviews in which he learned a great deal about sexual response patterns and techniques. He concluded that the prostitute population was not appropriate for physiologic study, but did learn how to approach more respectable volunteers who would be willing to participate in direct laboratory observations of sexual response.
A total of 694 individuals, including 276 married couples, ranging in age from 18 to 89, participated in the research program over a 10-year period. More than 14000 sexual acts were observed and measured. Most subjects were paid volunteers who readily agreed to masturbate or to have intercourse with their partners while being filmed or recorded by physiologic measurement devices. Among the most noteworthy findings of this research were the remarkable similarities in male and female
sexual physiology, the role of vaginal lubrication in female sexual arousal, and the physiology of multiple orgasms. Out of this work came the widely influential “four-stage model” of the sexual response cycle. The Masters and Johnson sexual response cycle served as the basis for their classification and subsequent treatment approach; deviations from the “normal” sexual response cycle constituted sexual inadequacies or dysfunction. Notable in this model is the absence of a “desire” phase, since desire is basically a subjective experience difficult to measure within a physiologically based model.
The result of their research program was an extremely detailed description of the major physiologic changes associated with sexual arousal and orgasm in males and females: changes in blood flow, vaginal lubrication, nipple enlargement, and other physiologic changes were described. Further, these physiologic changes were described over the course of the “sexual response cycle,” so that the changes take place progressively over time and in specific sequence. The four-stage model of Masters and Johnson serves as the central organizing schema for their observations of male and female sexual physiology, as well as the basis for their subsequent classification of sexual dysfunction.
The model includes the well-known phases of excitement, plateau, orgasm and resolution. Each phase is associated with specific genital and extragenital changes, and focuses almost exclusively on bodily responses to sexual stimulation, with minimal attention to cognitive or subjective aspects of sexual response. Within this model, Masters and Johnson emphasize the essential similarities in the male and female physiologic responses to sexual stimulation, drawing parallels at different phases of the cycle. For example, during the excitement phase, female vaginal lubrication is compared directly to penile engorgement and erection in the male, particularly in respect to parameters such as “reactive intensity”, response timing, and age-related changes. In their discussion of the vaginal-clitoral orgasm distinction, they again emphasize the relative uniformity of male and female orgasmic processes.
The overall contribution of this research to the understanding of sexual response is undisputed, but there have also been frequent criticisms of their work. Masters and Johnson acknowledged that their sample was unrepresentative in regard to age, race and educational status. Further, it seems plausible that individuals willing to perform sexual activities in the laboratory are not representative of the general population, and that the laboratory setting may have influenced the character of the sexual responses observed. Robinson6 has drawn attention to the largely contrived separation of sexual response into four discrete stages, especially the distinction between excitement and plateau, and suggests that the process of arousal is better conceptualized as a continuous progression of events. Another criticism of the Masters and Johnson model is the relative lack of synthesis of cognitive-affective states with the physiologic processes of sexual arousal.9 Subjective factors are generally overlooked in their model. Moreover, even when discussing changes in physiologic activity, they fail to provide an explanation for the observed patterning of autonomic, somatic, and central concomitants of sexual response. While Masters and Johnson have enumerated the specifics of physiologic response in great detail, there is a lack of explanatory concepts for integrating these separate response dimensions. Overall, one is left with an impressive but essentially disjointed description of physiologic events.
Human Sexual Inadequacy was based on Masters and Johnson’s therapeutic experiences with 790 patients, whose complaints fell into six major categories: for males, primary impotence (32 cases), secondary impotence (213 cases), premature ejaculation (186 cases), and ejaculatory incompetence (17 cases); for females, primary orgasmic dysfunction (193 cases) and situational orgasmic dysfunction (149 cases). The absence of sexual desire disorders in their case series is noteworthy. Although Masters and Johnson’s research focused on the specific physiologic changes taking place during sexual activity, their therapeutic model emphasized psychologic and social factors. Their women patients frequently described what they called “psychosocial repression”, in which “normal” and “natural” sexual responsiveness is inhibited by negative sexual messages, with religious orthodoxy identified as a significant source of sexual misconceptions.
Prior to 1970, most forms of female sexual dysfunction were referred to by the pejorative term “frigidity”. With the publication of Human Sexual Inadequacy, female sexual dysfunction began to be classified according to which specific phase of the four-stage arousal sequence was most affected. Masters and Johnson highlighted the importance of differential diagnosis based on the patient’s sexual history. They distinguished between primary and secondary, or situational, forms of orgasmic dysfunction, thus refining the treatment mechanisms to be used. However, the conceptualization and definition of sexual desire problems did not take place for almost a decade, until the separate contributions of Harold Lief and Helen Singer Kaplan. These were followed by the “psychosomatic circle of sex” concept, developed by John Bancroft.
Sexual response and psychiatry: contributions of Lief, Kaplan, and Bancroft
The first of three influential psychiatrists and sex therapists, Harold Lief addressed the need to include a desire or libido phase of sexual response, and a clinical approach for evaluating and treating disorders of this phase. Lief deserves credit for being among the first authorities to comment on the need for a greater focus on problems of sexual desire.10 Lief noted in an early paper that a substantial proportion of patients presenting at sex therapy clinics could not be diagnosed according to the classification proposed by Masters and Johnson. He proposed
that the new diagnostic term “inhibited sexual desire” (formerly “low libido”) be added to the classification of sexual dysfunction in women and men, and he suggested specifically that the diagnosis be applied to women who chronically fail to respond to sexual initiation. This proposal had immediate and lasting effects on the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders (DSM) classification. Lief observed that a large number of referrals for sex therapy (almost 50% in one early study) were due to a loss of sexual interest, in addition to problems of arousal or orgasm.
Another of Lief’s key contributions to the field was to focus attention on the role of sex hormones, and testosterone in particular, in the conceptualization of sexual desire phase disorders (“inhibited sexual desire”). Lief noted that testosterone is important for maintaining normal sexual desire or drive in both males and females; he considered studies of hypogonadal men and oophorectomized women in his model, and menstrual cycle effects on sex steroid hormones.11 In short, Lief drew attention to both the importance of sexual desire as a core issue in our understanding of sexual function and the significance of endocrinologic factors in understanding hypoactive sexual desire disorder. Studies in recent years, and many chapters in this book, illustrate the relevance and clinical importance of these observations.
Helen Singer Kaplan
Helen Singer Kaplan’s model of sexual function and dysfunction is grounded in her experiences as a sex therapist.12,13 Noting the relative neglect of motivational factors in the Masters and Johnson model, Kaplan criticized the field of sex therapy for failing to address the importance of sexual desire deficits in clinical disorders of sexual function. Accordingly, she recommended reconceptualizing the sexual response cycle to include three stages - desire, excitement, and orgasm; she observed that sexual dysfunction fell into these three categories, and that it is possible to be “inhibited” in one of these areas and still function normally in the other two.
The inclusion of “desire” as a separate stage of the sexual response cycle may have been Kaplan’s most significant contribution. Unlike excitement or orgasm, sexual desire does not necessarily involve the genital organs; rather, it involves sensations that motivate a person to seek out or become available to sexual experience. The desire stage is comparable to the traditional concept of “libido”, and Kaplan identifies the source of libido as activation of certain centers in the limbic system. The second stage, excitement, is identified with reflex genital vaso- congestion in both sexes. The third stage, orgasm, consists of reflex pelvic muscle contractions. A key postulate of this model is that the three phases of sexual response are mediated by separate but interrelated neurophysiologic mechanisms. While desire is believed to be mediated by central (i.e., brain) mechanisms, excitement and orgasm are associated with the stimulation of peripheral reflex pathways in the lower spinal cord. Although this distinction is appealing in some respects, Kaplan provided little direct evidence to support the differentiation of drive as centrally mediated in contrast to excitement and orgasm as peripherally based processes.
Kaplan argued that a disturbance in one of the three stages of sexual response does not necessarily imply that there are difficulties with the other stages. For example, a woman with low desire may be reluctant to initiate sex, but may still have pleasurable arousal and orgasm responses if she is induced or pressured into sexual activity. Problems with sexual desire are among the most difficult to modify, according to Kaplan, and accounted for a significant number of failures in her sex therapy program. Similarly, Kaplan cautioned that anorgasmia (lack of orgasm) should not be confused with uninterest in sex or with difficulty in becoming sexually aroused. In fact, she believed that failure to reach orgasm during intercourse was not necessarily a dysfunction at all, but perhaps a normal variation of female sexuality. For some women, the stimulation provided by intercourse is insufficient to trigger orgasm.
Criticisms of Kaplan’s three-phase model include the discontinuity between the centrally mediated desire phase and the peripherally mediated excitement and orgasm phases, and the lack of elaboration of the excitement and orgasm phases. Kaplan describes these phases in purely reflexive terms, and focuses exclusively on peripheral physiologic changes in defining excitement and orgasm. She strongly emphasizes the similarities between male and female physiologic responses during excitement and orgasm, but overlooks the role of extragenital or subjective changes during the latter phases of the response cycle.
Bancroft14 described four essential features of sexual arousal: (1) sexual appetite or drive, (2) central arousal, (3) genital responses, and (4) peripheral arousal. Included in the category of sexual appetite or drive, according to Bancroft, are both motivational factors and sexual arousability. Other authors, such as Basson,3 have viewed sexual arousability as a dimension separate from desire. Bancroft’s second component, central arousal, refers to central nervous system activation and atten- tional factors that underlie psychologic processing of sexual stimuli. In recent years, Bancroft and Janssen15 expanded this component of the model to include the processes of activation or excitation, and inhibition of central nervous systems. These processes are conceptualized to determine the degree and type of psychologic mechanisms in sexual dysfunction, which Bancroft and Janssen further speculate is related to neurochemical processes in the brain and spinal cord, such as alpha-adrenergic tone. Some pharmacologic studies provide support for this hypothesis.16 The third and fourth components, genital responses and peripheral arousal, have received the most extensive discussion to date, and have been the focus of much research in the past two decades.9
Bancroft postulates a “psychosomatic circle of sex”. In this model, thoughts and feelings about sex are integrated into several layers of processing of sexual stimuli in the brain, spinal
cord, and peripheral genital reflexes of men or women. Bancroft described a “central arousability system” consisting of connections or circuits in the medial preoptic areas of the hypothalamus, prefrontal cortex, and other brain and spinal centers of coordination. At this time, there is evidence of the role of spinal integrating neurons in control of rhythmic contractions during orgasm in males and females. Brain centers involved in arousal and orgasm have been similarly investigated by radioimaging methods such as positron emission tomography (PET) and magnetic resonance imaging (MRI). Other investigators have used peripheral measuring devices (e.g., vaginal photoplethysmography, Doppler ultrasound, genital MRI) for physiologic assessment of sexual response in women. These latter techniques are also described in later chapters.
Leonore Tiefer and the feminist perspective of women’s sexuality
Leonore Tiefer and others present a “social constructionist” model or perspective on female sexuality; in this view, definitions and categories of sexuality are the product of a specific social and historical environment.17 Deconstruction is the process of analyzing existing categories to assess their current validity and usefulness. Tiefer applies this analysis to the sexual response cycle model of human sexual function that originated with Masters and Johnson, and continues to play a prominent role in discussions of female sexual function and dysfunction.
Tiefer argues that the Masters and Johnson model was assumed before the collection of the research data, and in fact actually guided the selection of subjects and research methods. For example, Masters and Johnson selected only women able to be sexually responsive in the laboratory setting, although their responsiveness is not likely to be generalizable to all women. Similarly, the sample was not representative in terms of socioeconomic status, or in what is described as “sexual enthusiasm”. Tiefer also points out the potential problems associated with experimenter bias - Masters and Johnson acted as both researchers and “therapists” with many of their subjects - and the bias introduced by the definition of “effective sexual stimulation” as that which advances the subject through the sexual response cycle.
These limitations and biases are important in the study of female sexual dysfunction generally, since Masters and Johnson’s model has so long been the reference standard against which “normal” sexual function is measured. Deviations from the model are, by definition, outside the “norm” and therefore a sign of dysfunction. Among the limitations of this model, according to Tiefer, are a focus on sexuality as the performance of a “fragmented series of body parts” rather than a whole, that sexual dysfunction occurs when a body part does not function according to norms, and that dysfunction can be diagnosed adequately by medical tests and technology.
Masters and Johnson emphasized the similarities in male and female sexual response, and constructed the sexual response cycle to show the parallels between men and women. In presenting a feminist critique of the sexual response cycle, Tiefer suggests that insisting on the essential similarities between male and female sexual response may actually obscure some important differences. Men and women are raised with different sexual values and expectations, and the social and emotional meaning of sex is unlikely to be gender neutral. By reducing sexual response to a series of physiologic changes, Tiefer argues, the sexual response cycle ignores the context and meaning of sexuality, factors that are critical in the understanding and treatment of female sexual dysfunction.
In A New View of Women’s Sexual Problems,18 Tiefer and others criticize the DSM, the classification scheme used to categorize women’s sexual problems, as excessively medical, genitally focused, and mechanistic. In this “new view”, the pharmaceutic industry has coerced sex research in the direction of developing physical treatments for sexual problems, to the exclusion of sociocultural, psychologic, or social approaches. The medicalization of sexuality began in earnest with the US Federal Drug Administration (FDA)’s approval of sildenafil, and the growth of a new medical area of “male sexual dysfunction”. The development of female sexual dysfunction has followed. In Tiefer’s view, female sexual dysfunction is the pharmaceutic industry’s concept, which supports the development of pharma- ceutic/medical treatment, and is at odds with the complexity of women’s sexual problems.
The working group that produced the “new view” argues for a change in the nomenclature and classification of women’s sexual problems that is based on recognition of the differences between men and women, the relational context of sexuality, and the differences among women. This new classification scheme defines women’s sexual problems as “discontent with any emotional, physical or relationship aspect of sexual experience, including problems due to socio-cultural, political or economic factors, relationship factors, psychological factors, or medical factors”.
Rosemary Basson and the reconceptualization of female sexual dysfunction
Advances in the understanding of female sexuality are based in part on new research on changes related to aging, reproductive events, and relationship duration, as well as the importance of mental well-being and other psychologic and biologic factors. Recently, Basson has used these data to reconceptualize women’s sexual response and to expand and revise current definitions of female sexual dysfunction.19
Basson’s model contrasts with the more traditional models formulated by Masters and Johnson and Helen Singer Kaplan, in which sexual activity is a “linear progression of discrete phases plus a focus on genital arousal/congestion, rather than the subjective experience”. There are many facets of a woman’s sexual function and dysfunction that do not fit the more traditional views of the past 50 years. For example, research indicates that the awareness of sexual desire is not the most frequent reason women engage in sexual activity, that sexual fantasies may be a technique for focusing sexual thoughts rather than an indication of desire, and that a woman’s experience of sexual arousal has relatively little to do with her perception of genital changes. In contrast to Kaplan’s notion that sexual dysfunction could occur in one part of the sexual response cycle without affecting other parts, new evidence demonstrates that correlation or comorbidity of dysfunction is common.
Basson emphasizes that women have many reasons for engaging in sex, and that these reasons - the desire for emotional intimacy, for example - may have little or nothing to do with feelings of sexual desire. Further, she describes a potential “disconnect” between a woman’s feelings of sexual arousal and the physiologic changes, such as genital vasocon- gestion, that typically accompany sexual arousal. Basson’s model of the sexual response cycle is circular, and includes the multiple sexual and nonsexual reasons for engaging in sex, the psychologic and biologic influences on arousability, and subjective feelings of arousal and desire. Within this model, there are many factors that may instigate sex, and a variety of potential positive outcomes, with a range of sexual response cycles in different women. Factors that may interfere with a satisfactory cycle include: minimal emotional intimacy; lack of appropriate sexual stimuli; negative psychologic factors such as distraction and fear; and fatigue, depression or medication effects that reduce arousability. According to Basson, even when a dysfunction is logical and adaptive, it can still cause a woman to feel considerable personal distress and require treatment.
Subjective arousal plays a central role in this model. Feelings of subjective arousal do not correlate well with psychophysiologic measures of genital congestion. Indeed, emotions and thoughts have a stronger influence on the subjective experience of arousal than feedback from genital congestion. It is also possible for a woman to experience healthy sexual vaso- congestion without having any feelings of sexual arousal or excitement.
Basson et al.20 presented revised and expanded definitions of women’s sexual dysfunction developed by an international committee organized by the American Foundation for Urological Disease. These new definitions include sexual desire disorder (the absence of not only sexual thoughts and desire but also responsive desire), sexual arousal disorder (subdivided into subjective arousal disorder, genital arousal disorder, and combined arousal disorder), orgasmic disorder (lack of orgasm despite high sexual arousal), dyspareunia and vaginismus, and persistent sexual arousal disorder (the presence of persistent genital congestion that is inappropriate and intrusive).
The pharmaceutic era: will there be a “drug” for women?
The development of selective phosphodiesterase type 5 inhibitor drugs (sildenafil, tadalfil, and vardenafil) has irrevocably altered medical and societal concepts of sexual dysfunction, and how we view sexual problems in the “sildenafil age”. These drugs have been widely used in men (about 30 million current users worldwide), and tested in more than 100 prospective, randomized, controlled trials. Although initially questioned for their cardiac safety, these drugs (selective phosphodiesterase type 5 inhibitors) have been shown to be generally safe and effective in men, with additional beneficial effects on mood in men for whom the drugs are effective.21 Despite their success in the treatment of erectile dysfunction problems in men, selective phosphodiesterase type 5 inhibitors have not had consistent success in studies in women.22 The paucity of well-controlled studies may be due, in part, to methodological problems in conducting clinical trials in women.23 While sildenafil has been shown in some studies to increase vaginal blood flow and genital vasocongestion in response to sexual stimulation in women,24,25 results from clinical trials in outpatient settings have been difficult to interpret.
Based on the inconsistent results obtained, Pfizer announced in early 2004 that it was discontinuing its clinical development program of selective phosphodiesterase type 5 inhibitors for sexual arousal disorder in women. The company indicated that it would continue to investigate female sexual dysfunction generally and to consider development of other treatments. The androgen patch for women, which was developed by Procter & Gamble for women with hypoactive sexual desire disorder, has similarly been withdrawn recently from FDA review. Despite these apparent setbacks, basic and clinical research in female sexual dysfunction has expanded with the entry of the pharmaceutic industry into this area and has made significant advances in recent years. Later chapters in this volume provide strong evidence of this trend. However, a comprehensive and holistic approach to management of sexual dysfunction in women, which takes medical and psychosocial factors into account, is now needed. We hope this volume will support this overall direction of change and provide specific signposts.
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