Fig. 2.1
Embryo–fetal sexual differentiation
Fig. 2.2
Male and female embryo–fetal sexual differentiation
Internal genitalia. Under the action of the testicular androgens, the Wolffian mesonephric ducts give rise in the male fetus to the epididymis, vasa deferentia, and seminal vesicles. In the female sex, given the absence of AMH, the Müllerian paramesonephric ducts form the uterine tubes, the uterus, and the upper third of the vagina. Therefore, the Wolffian ducts degenerate in the XX fetus owing to the lack of androgens, whereas the Müllerian ducts return in the XY fetus by the action of the AMH. It should be noted that the action time frame of the AMH is short: the testicular secretion starts by the end of the 7th week, and the Müllerian ducts become refractory to its action from the 10th week.
External genitalia: the undifferentiated outlines evolve into male structures under the action of the dihydrotestosterone, a powerful androgen derived from the action of the 5-α-reductase enzyme on the testosterone. Thus, the penis originates from the genital tubercle, whereas the labioscrotal folds enlarge and fuse in the ante-posterior sense to form the scrotal sacs. In the female fetus, the lack of androgens allows the clitoris to originate from the genital tubercle, and the urogenital folds to remain separate, forming the labia majora. However, the mere presence of testosterone and AMH is not enough, for the final action depends on the binding of each molecule to its specific receptor, and on the proper functioning of the subsequent molecular cascade.
The same sexual differentiation phenomenon proves to be more complex and determinant, given that under the influence of the sexual hormones circulating in the fetus the dimorphic development of certain brain areas is produced too. Furthermore, the brain, like the internal genitalia, is monotypic, and in it the feminization principle also prevails, unless there is an adequate level of circulating androgens [7].
Sexual differentiation of the human brain takes place approximately between weeks 16 and 28 of embryonic development, and the specific hypothalamic and hypophyseal functions (cyclic in women and noncyclic in men) are determined at that moment.
The hypothalamus is considered to be the main regulating center of sexual behavior in humans. In the pre-optic nucleus the hormone that releases gonadotropins (GnRH) is produced, which stimulates the anterior pituitary so that it can in turn produce luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Both control the steroid hormone secretion by the gonads (estradiol, progesterone, and testosterone).
This complex system of hypothalamus–hypophysis–gonads presents secretory self-regulation by means of positive and negative feedback mechanisms. Moreover, the GnRH modulates the catecholaminergic neurotransmission, direct and indirect arbiter of the sexual output of the individual (while dopamine stimulates the sexual function, and serotonin and prolactin inhibit it, the balance dopamine/serotonin becoming crucial in this field). Other substances implicated in the complex world of the neurochemical interactions that modulate human sexuality are: GABA, ACTH, cortisol-releasing peptide, endogenous opioids, and acetylcholine.
The secondary sexual characteristics are induced by the CNS and controlled by a substantial increase in the circulating androgens or estrogens, as well as the female-specific functions regarding menstruation, gestation, and lactation. The precise way in which CNS “rules” the beginning of puberty is still unknown. It has been considered that one of the mechanisms implicated is the reduction of the sensitivity of the hypothalamus to hormonal negative feedback [8].
Since puberty, hormonal imbalances may alter secondary sexual characteristics, generating different physical alterations. Nevertheless, the influence of the hormone levels on desire and sexual behavior is much less clear at this point of development and at subsequent stages.
Once the fundamental biological factors in the formation of human sexuality are determined, it is worth going deeper into the other fundamental pillar, that is to say, that related to the formation of a sexual identity or psychosexuality.
Communication and early social learning are of paramount importance in determining early sexual behavior. Therefore, control over sexual behavior as well as of mating within our species, is to a great extent determined by the earliest social interactions, together with the aforementioned biological determinants.
In both sexes the inadequate availability of sexual hormones in the blood plasma reduces the intensity of sexual desire. But when the levels are adequate, the dependence of sexual desire on their fluctuations is negligible in comparison to the relevancy of the psychosocial kind of stimuli. McConaghy [8] believes that female sexual desire can be more influenced by psychosocial factors than masculine desire. Even so, the paucity of scientific research concerning this issue is surprising.
The development and maturation of the individual’s sexuality, as well as the personality, go hand in hand with the establishment of the ability to experience love for certain objects, sexual or not (parental, filial, narcissistic, group). In the case of sexual love we can say that “healthy” sexuality is accompanied by the foundation of a certain degree of intimacy, empathy, and confidence in the beloved object, which in turn leads to the enhancement of the personal identity (including the sexual identity and narcissism itself). These values become the fundamental basis of a relationship in which sexual activity plays the role of positive reinforcement and affective catalyst, aside from its reproductive function.
Sexuality is therefore a more general phenomenon than plain physical sex and a more restricted one than the set of behaviors derived from the libidinal drive and directed according to Freud toward the achievement of pleasure, and according to many post-Freudian authors (such as Fairbairn), toward the establishment of interpersonal relationships.
There is a widespread consensus in the psychoanalytical literature on the key importance of earlier relationships in the construction of gender identity and sexual orientation. Authors such as Kernberg [8, 9], from a conciliatory perspective based upon the theory of object relations, emphasize the relevant role of the relational configurations that populate the internal world of boys and girls. They are the result of the incorporation of the so-called object relations dyads, consisting of one representation of the Self, another of the object, and an affection that bonds them together.
Contemporary authors such as Stoller [10–13], who was especially dedicated to this sphere of knowledge, point out how gender identity seems to be acquired in very early stages.
The utmost significance that used to be attributed to the “Oedipal Complex” is no longer ascribed to it, and it consists now of nothing but a cultural construction of mythical proportions. It must be noted that from certain sectors of psychoanalysis it is also highlighted that the sense of the Self and of the other evolves through the fact that separate minds are able to share feelings and intentions in a process of mutual recognition. This recognition can be established through a dyad mother/son, or father/daughter, or any asymmetrical relationship, as long as the needs of the other are not falsified through constructions or representations that justify and disguise domination.
The androcentrism of psychoanalytical theory concerning sexual differences stems from that point, of the double absence and invisibility of what the father does in the scenario where the girl and the mother end up finding their place and developing their subjectivity [14].
In fact, the dominant factor in humans that determines the intensity of sexual desire, leaving aside the aforementioned hormonal factors, is of a cognitive–affective kind, and is clearly constrained by psychosocial factors. It is worth noting at this point how the affective memory is related to the limbic system, which is the nervous substrate of affection and of the rest of the appetitive functions.
Because sexual activation also includes the implementation of the limbic system under the influence of a particular cognitive–affective state, which stimulates the peripheral and central nervous systems that determine the congestion and lubrication, and increases the focused sensitivity of the genital organs, providing a central feedback “self-realization” of that genital activation and the subsequent psychological excitement.
In that regard, Kernberg [8,9,15,16] adds that sexual arousal is a specific affection that shows all the features of the affective structures, and constitutes the central building block of the so-called sexual or libidinal drive as a general motivational system. Sexual arousal is the basic affection that constrains the appearance of a more complex psychological phenomenon, erotic desire, in which the sexual arousal seems to be bound to the emotional relationship with a specific subject.
The source of desire is not an anatomical body but a body that is built through the array of discourses and intersubjective practices. Both girls and boys organize themselves through their relationship with other subjects (for instance, the mother) who aren’t just objects for the child, because both the girl and the boy are able to recognize that subject as different from them and, at the same time, as akin to them. In this way, the intersubjectivity plays a role in the structuring of the psychological world. It may be noted that uneven consequences arise from a double sexual standard, the fact that admiring women or giving them recognition only for their physical attributes poses a difficulty for their mental balance, as well as the extra work to which the female psyche is subject if it intends to reconcile the multiplicity of demands of its motivational systems [17].
To conclude this introduction we attempt to define in a simple and operational way a general consensus as to what constitutes “abnormal or deviant” sexual behavior, that is:
Anything that is destructive or damaging to the subject who displays it and to those who get involved in it.
Anything that is not oriented to the other in the strict sense.
Anything that excludes the stimulation of the subject’s own genital organs and those of their partner.
Anything that is inappropriately associated with feelings of guilt and/or anxiety.
Anything that shows a compulsive repetitive nature.
We share with many authors a preoccupation that has arisen from the manifest neglect in clinical practice in documenting the medical/sexual history and its psychopathological manifestations in the individuals who visit the doctor. More frequently than would be desirable, it is the health professional themselves (unlike the patients) who perceive this issue as a complicated area to explore, and thus a subject to be avoided. It is essential to explore the patient’s love life, including sexual patterns, as well as their fantasies and the nature of the object relations that are established in the context of their sexual behavior [16].
2.3 Sexual Dysfunctions
Sexual dysfunctions represent a group of heterogeneous disorders and include an array of processes that affect the general population, generating a high impact on quality of life and interpersonal relationships.
They are usually underdiagnosed and undertreated, and in them etiopathological aspects of biological, psychosocial, and interpersonal nature overlap. It is important to determine any underlying disorder or incurring psychosocial factor when evaluating a patient who has sexual problems, to such an extent that it has been stated that the sexual dysfunction may in fact be a symptom or side-effect, and not a primary pathology [2]. Additionally, in all cases carrying out surveillance of the possible organic causes is unavoidable (highly frequent in the case of a man’s erectile dysfunction), as well as toxic and pharmacological causes or other psychiatric disorders, pre-dominantly of an affective nature.
Historically, sexual response has been understood as a linear process in various stages, initially defined by Masters and Johnson (excitement-arousal-orgasm-resolution), and later modified by Kaplan into a triphasic model of desire arousal and orgasm [2].
From this model, sexual dysfunction has been historically classified with regard to a disturbance of the sexual act, attributable to various causes. Among them [18]:
Disturbances in the physiological processes specific to each stage of the sexual response cycle (excitement-arousal-orgasm-resolution).
Algesic disorders that hamper either the performing of sexual intercourse (dyspareunia, vaginismus) or its achievement (post-sexual dysphoria).
All share a common trait: the anxiety they cause to sufferers and/or their partners. This anxiety may trigger the dysfunction, or act as a factor that prolongs it once it has set in [18].
However, as we see later, today a new, more complex and nonlinear model of sexual response has been adopted, which includes emotional and relational factors, as well as the interference from outside sexual stimuli, together with those of a cognitive kind.
Another peculiarity to be taken into account, as reflected in the new edition of the DSM, is that sexual excitement includes both a subjective and a physiological or genital arousal [19]. These two are often different from each other, and studies have shown that there is a poor correlation between subjective and physiological arousal. Thus, healthy women with sexual arousal disorder have shown normal genital vessel congestion as a response to erotic stimuli, despite protesting that experience a low level of subjective arousal [20].
The epidemiology shows us how regular medical practice is not in accordance with the facts regarding disorders associated with sexuality, and the underrated perception of this psychopathological characteristic that is so frequently neglected.
*Women
The prevalence of sexual dysfunctions in women has been estimated for years to be about 43 %, on the basis of a National Health and Social Life Survey Study, which examined a cohort of adults in USA in 1992.
More recent data from a transversal female population-based case-control study in the United States (Prevalence of Female Sexual Problems Associated with Distress and Determinants of Treatment Seeking) determined a prevalence for any sexual dysfunction of 44.2 % [21].
According to the National Health and Social Life Survey more women (43 %) than men (31 %) gave information about their sexual problems. Among those women who gave information about any kind of sexual difficulty, problems related to sexual desire were the most common (average 64 %), followed by difficulties with orgasm (average 35 %), difficulties with arousal (average 31 %), and sexual pain (average 26 %) [22].
It is worth noting that women vary significantly when it comes to assessing the importance that they attach to the practice of sexual intercourse, as well as their sexual practice of preference, their views on the optimal sexual frequency, and the amount of stimulation necessary to obtain adequate sexual arousal and satisfaction [23]. It is not hard to imagine that the multidimensional gender variable explains such a wide variability.
Another factor to be taken into account is age. Most studies offer evidence that sexual activities, as well as sexual function, decrease with age. This decline has usually been seen to start from the 30–40s age bracket. In addition, many women describe a decline specifically associated with menopause. Only a small percentage of women in longitudinal studies (5–15 %) informed of an increase in sexual function and activities with age. Nevertheless, it must be clarified that a decline in sexual function and activities does not automatically imply the presence of a dysfunction or a sexual disorder [24].
*Men
Different studies show a high prevalence of sexual dysfunction symptoms in men, reaching 64.3 % in those over 40 [25].
A recent study on an Australian male population aged between 20 and 64 years who have been sexually active in the last year, confirms that 34 % of men refer to at least one sexual difficulty; 48 % of men with any sexual difficulty presents with problems maintaining an erection, and 24 % refer to delayed ejaculation; 11 % of the sample related to having experienced a loss of interest in sex in the last year, and 7 % complain about premature ejaculation [26].
Also, the lack of interest in sex or a decrease in the libido is associated with erectile dysfunction, premature ejaculation, and delayed ejaculation in 38 %, 28.3 %, and 50 % of men respectively [27].
As regards nosology, in the first versions of the Diagnostic and Statistical Manual of Mental Disorders (DSM) of the American Psychiatric Association only two sexual dysfunctions are set out: frigidity (with regard to women) and impotence (with regard to men).
The category psychosexual Disorders was included for the first time in the third edition of the Manual (DSM-III) in 1980, where it was defined as “inhibitions in sexual desire or the psycho-physiological changes that characterize the sexual response cycle” [28]. The diagnostic of “inhibited sexual desire” includes inhibitions within any of the sexual stages indicated by Masters and Johnson in 1966 [29]: excitement-arousal-orgasm-resolution. In 1987, in the DSM-III (DSM-III-R) revision, “inhibited sexual desire” was subdivided into two categories “hypoactive sexual desire disorder” (lack of interest in sex) and “sexual aversion disorder” (phobic aversion to sex). Since then, progress has been made with regard to both the diagnostic classifications and the definition of sexual dysfunctions.
The DSM-IV (published in 1994, followed by its revision, or DSM IV TR, in 2000) gathers four categories of sexual dysfunction, following again the linear model of sexual response by Masters and Johnson: “disorders of sexual desire, arousal, and orgasm, and disorder of sexual pain.” In addition, in order to perform a diagnostic of the disorder, the sexual performance must cause significant upset or interpersonal difficulties [30]. The DSM-IV also frames the disorder in terms of the nature of its inception (“lifelong vs acquired”), the context in which it takes place (“generalized vs situational”), and etiological factors (due to primarily psychological factors, with the contribution of medical factors, or due to substance use).
While waiting for better adaptation and implementation of the DSM 5, as of today, the DSM-IV TR diagnostics are still the most frequently used by the majority of psychiatrists. Therefore, and because the new DSM edition feeds on them in different ways, a detailed analysis of the different sexual dysfunctions based on the linear model of sexual response is carried out below, later moving forward to revise, in a briefer way, the different nosographic changes as set down in the DSM 5 [19].
2.3.1 Sexual Desire
2.3.1.1 Hypoactive Sexual Desire
By hypoactive sexual desire, sexual frigidity or a decrease in sexual desire we understand a clinical condition characterized by an absence (anaphrodisia) or decrease in sexual fantasies and in the desire to engage in sexual intercourse with the partner concerned. This clinical picture is often (but not necessarily) accompanied by difficulties with other stages of the sexual cycle (arousal, orgasm), or by a previous history of adverse previous sexual experiences (dispareunia, vaginism).
The decrease or absence of sexual desire appears, from an epidemiological point of view, more frequently in women, in their adult life and after a period of normal sexual activity, coinciding with extrinsic stressing factors or with periods of psychological unease, sometimes influenced by various psychiatric disorders (major depressive disorder or anxiety disorder) and/or organic disorders.
Frigidity can in its turn come to be an important source of psychological upset associated with low self-esteem. Another possibility is that this clinical picture represents in itself a defense mechanism against unconscious fears that are unacceptable to the individual, such as fantasies of a homosexual or paraphilic nature. Nor is the situation unusual in which hostile feelings toward the partner, a deterioration in the loving relationship, or the expression of a situation of abuse or gender-based violence lie beneath hypoactive sexual desire.
The actual prevalence of this clinical picture can approach 20 % of the general population, being:
A global illness that extends to all sexual relationships of the individual, and reveals difficulties with emotional bonding and in facing intimate relationships.
Or an affection circumscribed to certain situations, such as with a certain partner or featuring a certain sexual practice.
Aspects such as the kind of couple relationship that has been established, the sociocultural environment to which the individual belongs, as well as his or her intellectual and educational level, should all be checked, running joint interviews if necessary. In fact, it is not uncommon for the decrease in the sexual desire of one of the members of the couple to be a response to an increase in the desire and demands of the other, or that the decrease in desire alternates and is transitory for both members of the couple.
2.3.1.2 Sexual Aversion
In this clinical picture, what was noted in the previous subsection reaches its most extreme manifestation in the shape of a rejection of everything related to sexual practices, with an active and lasting avoidance of sexual intercourse.
The patient who suffers sexual aversion experiences disgust and rejection of some particular aspect of genital or sexual contact, suffering a real terror at the mere possibility of it happening, accompanied by great anxiety. The association of symptoms frequently observed in anxiety disorders with those of mood disorders forces us to effect an exhaustive differential diagnostic for all of them.
2.3.1.3 Erotomania or Hyper Erotism
At the polar opposite of the decrease in or rejection of sexual desire is hyper erotism or excess libidinal desire or sexual impulse. This picture, which is also known as erotomania (or hypererosia if we make reference to the same phenomenon in the animal kingdom) [31], is accompanied by a predominance of cognitions and mental images full of sexual content, generic or specifically crystallized around certain people, absolutely independent and detached from any coital and reproductive function.
This phenomenon is more akin to young individuals who can find in their excess of sexual desire a source of conflict and concerns given its unadaptive nature.
The ICD 10 [31] includes in this section two classical forms, the male form (satyriasis) and the female form (nymphomania). In both cases reference is made to serious disorders dealing with an excess of sexual desire, with significant repercussions in the social and psychic life of the patients, who live under the clear constraints of a disorder that acquires a compulsive nature.
2.3.2 Excitement Phase
During the excitement stage we can find different kinds of dysfunction, depending on the type of sex that is the object of analysis.
2.3.2.1 Male Impotence
The male can find it difficult or even impossible to obtain or maintain a penis erection that enables penetration and the achievement of coitus. This phenomenon is known as erectile dysfunction or impotence.
It is a frequent phenomenon, provided that it happens occasionally, as an episode, and does not create difficulties when it comes to establishing future interpersonal relationships. In the elderly a further delay in obtaining the erection and orgasm is also relatively frequent (responding to a physiological cause typical of advanced age), or in those cases in which there is inadequate sexual stimulation in terms of the stimulation object, intensity, and/or length. When the problem is more relevant and lasting, this is known as actual psychogenic impotence.
In an epidemiological study carried out throughout the world by GOSS (the Global Online Sexuality Survey) in a cohort of 1,133 English-speaking men, a prevalence of male impotence of 33.7 % was found [34].
In a recent study, Giuliano and collaborators [35] indicate a prevalence of male impotence less than 10 % of men under 50 and 20 % of those over 60. Risk factors associated with erectile dysfunction are age, cardiovascular diseases, diabetes mellitus, hypercholesterolemia, smoking, depression and other mental illnesses, psychological conflicts, and unfavorable socio-economic constraints.
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