Prevalence and Risk Factors of Sexual Dysfunction in Men and Women

Definitions and Outcomes

Sexual dysfunction is highly prevalent in men and women, although estimates vary depending upon the definitions and means of assessment used. From a psychiatric perspective, most definitions are based upon the four-phase model of Masters and Johnson [1], and Kaplan [2].

The first phase, sexual desire, consists of the motivational or appetitive aspects of sexual response. Sexual urges, fantasies, and wishes are included in this phase. The second phase, sexual excitement, refers to a subjective feeling of sexual pleasure and accompanying physiologic changes. This phase includes penile erection in men and vaginal lubrication in women.

The third phase, orgasm or climax, is defined as the peak of sexual pleasure, with rhythmic contractions of the genital musculature in both men and women, and ejaculation in men. The final phase is resolution, during which a general sense of relaxation and well-being is experienced.

In men, a refractory period for erection and ejaculation usually occurs during this phase. Sexual dysfunctions can be considered an alteration in one or more phases of the sexual response cycle, and this four-stage model forms the basis for classification of the sexual dysfunctions in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) [3].

Based upon this model, four major categories of sexual dysfunction are identified by DSM-IV as follows (Table 1): 1) sexual desire disorders, including hypoactive sexual desire disorder (HSDD) and sexual aversion disorder; 2) sexual arousal disorders, including female sexual arousal disorder (FSAD) and male erectile disorder, or erectile dysfunction (ED); 3) orgasmic disorders, including female orgasmic disorder, male orgasmic disorder, and premature ejaculation (PE); and 4) sexual pain disorders, including dyspareunia and vaginismus. Additional categories include sexual dysfunction due to a general medical condition, substance-induced sexual dysfunction, and sexual dysfunction not otherwise specified. Examples of the latter category include a lack of subjective erotic feelings, despite presence of normal arousal and orgasm, or the presence of a sexual dysfunction of undetermined origin. A revised and expanded classification for female sexual dysfunction recently has been proposed [4••], which incorporates dysfunctions due to organic and psychogenic etiologies. The definitions of desire and arousal difficulties in women have been broadened, and a new category of nongenital sexual pain disorders has been proposed.

Sexual dysfunctions impact significantly on mood, selfesteem, interpersonal functioning, and overall life satisfaction [5,6]. In the Massachusetts Male Aging Study (MMAS) [7], a large-scale epidemiologic study of ED in middle-aged and older males, a strong correlation was observed between the occurrence of erectile difficulties and selfratings of depression. Men with partial or complete ED rated themselves as significantly more depressed than those with normal erectile function. Moreover, the association between depression and ED was found to be independent of age, health status, or other mediating factors.