In retrospect, sexual disorders have a significant impact on an individual’s quality of life (Lindau et al., 2007). It is also apparent that these disorders bear immense significance to the clinical practice (Kingsberg, 2011). Despite their impact, most physicians do not seem to be interested to engage in extensive discussion with patients regarding sexual desire problems. This phenomenon is, probably, attributable to several reasons including time constraints, lack of efficient therapeutic interventions and insufficient knowledge. One of the most debilitating sexual desire disorders is hypoactive sexual desire disorder (HSDD). HSDD is also known as inhibited sexual desire (ISD) (Rice & Kim, 2015). HSDD is characterized by decreased or absence of desire for sexual activity and sexual fantasies which causes interpersonal difficulties, as well as personal distress (Nappi et al., 2010). In some circumstances, the diagnosis of HSDD exhibits co-morbidity to an underlying sexual dysfunction. However, this disorder is not exclusively attributed to the effects of any substance, pathology or another psychiatric disorder (Basson et al., 2010). Even though some clinical experts have hypothesized the causes of HSDD to be associated with biological imbalances, the pathophysiology of this disorder remains unknown. As such, efforts to develop a comprehensive treatment and management strategies have not achieved remarkable success. Therefore, this literature review aims at providing an overview of HSDD.
Epidemiological trends of HSDD exhibit gender inequalities in which women are more affected than men. Research studies indicate that sexual dysfunction occurs at a higher magnitude among women than men. This phenomenon is evidenced by several studies which have investigated sexuality. According to Gingell et al. (2005), an estimated 13% to 28% of men in the US were experiencing low sexual desire problems as compared to 26% to 43% among women by 2005. Overall, it is estimated that up to 25% of women in the US are suffering from HSDD (Warnock, 2002). Evidence the high prevalence of HSDD among women was reaffirmed by the findings of the WISHes (Women's International Study of Health and Sexuality) which showed that 24% to 36% of women experienced low sexual desire (Barton, Koochaki, Leiblum, Rodenberg & Rosen, 2006). In another prospective study, the prevalence of HSDD among women was found to vary with age in which middle-aged women (45 to 64 years) have the highest prevalence of 12.3%, whereas those aged 18 to 44 years and older than 65 years have prevalence rates of 8.9% and 7.4%, respectively (Shifren, Monz, Russo, Segreti & Johannes, 2008). On the other hand, the prevalence of HSDD seems to increase with aging which causes a significant decrease in sexual desire among men and women. A prospective study carried out by Brotto (2010) showed that only 4% of women had sexual desire at the age of 67 years compared to 14% among men. This was contrary to the trends in 16 to 24 years of age in which 72% and 50% sexual desire were reported in men and women, respectively. Overall, it is reported that the prevalence of HSDD is similar in the US and UK, especially with reference to the prevalence among women in which 1 in every 10 women is experiencing HSDD (Clayton, 2010).
History of HSDD
Over the decades, definition and classification of sexual dysfunction has been advancing year-by-year due to extensive scientific inquiry on sexual desire problems within the global population. Initially, two sexual dysfunction; impotence among men and frigidity among women, were recognized. These dysfunctions were attributable to the biological functions of the genitals. Following the description of these sexual dysfunctions in 1970, sex therapy became the mainstay for the management of low sexual desire. Despite the recognition of low sexual desire in the early 1970s, this condition was not categorized as one of the main sexual dysfunction until 1977 when Harold Lief and Helen Singer Kaplan described it independently. This is where the terms ‘Hypoactive sexual Desire’ and ‘Inhibited Sexual Desire’ emerged as the description for HSDD by Kaplan and Lief, respectively (Irvine, 2005).
It was from the work of Leif and Kaplan, sex therapists that led to the inclusion of HSDD into the Diagnostic and Statistical Manual of Mental Disorders (DSM). As such, HSDD appeared in DSM-III which was published in 1980. This marked the beginning of a universal diagnosis of HSDD to avoid misdiagnosis attributable to cultural differences. Ordinarily, low sexual desire is defined from different social contexts in which some cultures do not consider it as a sexual dysfunction, but rather a normal condition. It is also apparent that the magnitude of low sexual desire varies across cultures. For instance, it is reported that American populations exhibit a higher sexual desire compared to Asian populations (Brotto, Chik, Ryder, Gorzalka & Seal, 2005).
Later in 1987, the revision of DSM-III (DSM-II-R) created two subdivisions of ISD: Sexual Aversion Disorder (SAD) and Hypoactive Sexual Desire Disorder (HSDD). Further revision on the DSM-III-R criterion led to the inclusion of personal distress as part of HSDD diagnosis as described in DSM-IV of 1994 (Irvine, 2005). Recently in 2013, DSM-5 split HSDD into two subsets: female sexual interest/arousal disorder and male hypoactive sexual desire disorder. The scientific rationale for creating this distinction was based on the fact that the intensity and frequency of sexual desire vary between men and women (American Psychiatric Association, 2013a).
Etiology of HSDD
Even though the pathophysiology of HSDD remains a mystery, it etiology is clearly understood. Clayton (2010) reports that the causes of HSDD are multifactorial in which an array of causative and contributing factors exist. Clinical studies suggest interplay among psychological, neurological and hormonal factors which is responsible for the balance of excitatory and inhibitory activities in the brain. Ordinarily, dopamine, testosterone, progesterone, and estrogen are considered as the main excitatory factors which are responsible for sexual desire. On the other hand, prolactin and serotonin are antagonistic to excitatory factors; thus, they enhance inhibitory activity (Clayton, 2010). In general, testosterone and estrogen deficiencies are considered as the principle causes of HSDD.
Low testosterone has been hypothesized as one of the main underlying causes of HSDD. Biologically, testosterone plays integral roles in controlling sexual behavior, as well as exciting sexual activity. Overall, testosterone is responsible for genital engorgement in both men and women. It is also controls clitoral and vaginal physiology including lubrication and sensation (Brundu et al., 2003). As such, it is apparent that testosterone controls the physiology of genitals in humans. Therefore, low production or lack of it has been found to be associated with physiological consequences. According to Davis and Tran (2001), lack of testosterone leads to low libido, as well as decreased sexual pleasure. This explains why menopausal women experience low sexual desire compared to young women due to the decline of testosterone production.
Lack of estrogen has been identified as another cause of HSDD. Ordinarily, estrogen is responsible for sexual responsiveness. It also controls the physiology of the female genitalia through lubrication. In the case of HSDD, estrogen deficiency leads to vaginal dryness, mood changes and hot flashes. Vaginal dryness is usually responsible for painful intercourse which affects sexual pleasure and receptivity. Moreover, lack of estrogen causes imbalance of inhibitors which regulate sexual response cycle such as selective serotonin reuptake inhibitors (Nappi et al., 2010). For instance, it leads to sleep disturbances; thus decreasing the quality of life as a result of personal distress.