Sexual dysfunction is a common problem among the general population as well as among those suffering for psychiatric disorders and/or receiving psychotropic drugs. Research on sexual dysfunction with the exception of male erectile dysfunction is scarce. There are various aspects that make assessment of sexual dysfunction related to psychotropic drugs difficult. These include the potential biases associated with (a) patient selection (The study may include a greater number of patients who pay more attention to sexual matters and/or who are more willing to report on such matters.); (b) the assessment procedure used (self-report, questionnaire, or direct questioning); (c) the type of measurements used (objective versus subjective measurements); (d) the gender differences in the assessment (Sexual effects of psychotropic drugs are better documented in men than in women.); and (e) the lack of a baseline assessment (Demyttenaere, De Fruy, & Sienaert, 1998). An added difficulty is the differentiation between the effects of psychopathology and its course and the effects of psychotropic medication (Peuskens, Sienaert, & de Hert, 1998).

However, in spite of these limitations in the evaluation and the bias involved, most published studies agree that patients with schizophrenia treated with antipsychotics have a high prevalence of sexual dysfunction, ranging from 25% to 60% (Demyttenaere et al., 1998; Peuskens et al., 1998), and of problems derived from hyperprolactinemia, such as amenorrhea, with an incidence in women even higher than 50% (Ghadirian, Chouinard, & Annable, 1982; Sandison, Whitelaw, & Currier, 1960).

Sexual dysfunction and other reproductive problems have been given particularly little attention and often are underestimated in daily clinical practice with schizophrenic patients. This is partly because for years it was assumed that these patients had little sexual activity (Peuskens et al., 1998).

However, the few data available, obtained from research on risk behaviors associated with HIV infection, show that 50–60% of these patients have some type of sexual activity (Cournos et al., 1994; Demyttenaere et. al. 1998, Kelly et al., 1992; Susser et al., 1995; Thompson et al., 1997). It has recently been reported that approximately 80% of stabilized psychotic patients of both sexes have partner relations, and over 75% of men have masturbatory activity (Dickson & Glaser, 2000). It was also assumed for years that schizophrenic patients have sexual problems and deviant sexual behavior; however, no clinical evidence has been found to support this assumption (Demyttenaere et al., 1998). On the other hand, until clozapine was introduced in 1975, it was also assumed that hyperprolactinemia was an unavoidable problem associated with antipsychotic treatment.

However, with the introduction of clozapine and more recently with the marketing of new atypical antipsychotics the situation seems to have changed; in addition to clozapine, atypical antipsychotics such as olanzapine, quetiapine, and ziprasidone do not appear to be associated with a significant increase in prolactin levels, sexual dysfunction, and other reproductive-related side-effects (Petty, 1999). The data currently available suggest that the incidence of sexual dysfunction differs depending on the antipsychotic used (Knegtering, Blijd, & Boks, 1999; Montejo, 2000; Montejo, Llorca, & Izquierdo, 2000). On one hand, various studies had already shown that the incidence of sexual dysfunction was high, 25–60%, in patients treated with conventional antipsychotics such as thioridazine (Kotin, Wilbert, Verburg, & Soldinger, 1976; Sandison et al., 1960), with conventional drugs other than thioridazine (Ghadirian et al., 1982), with conventional drugs also including thioridazine (Sullivan & Lukoff, 1990), or with risperidone (David, Crawford, & Breier, 1998; Knegtering et al., 1999; Montejo, 2000; Shiwach & Carmody, 1998).

On the other hand, the data available suggest atypical antipsychotics are different not only from classical ones (Aizenberg, Modai, Landa, Gil-Ad, & Weizman, 2001); furthermore, data available suggests that atypical ones differ from one another (David et al., 1998; Knegtering et al., 1999; Montejo, 2000). Systematic data on quetiapine and ziprasidone are lacking; however, in registrational clinical trials with these drugs, frequency of sexual dysfunction appears to be very low (Physicians’ Desk Reference, 2001).

Although clinical trials are essential in assessing the effect and value of an intervention because they provide researchers a methodological control on potential confounding factors and maximize the internal validity, inclusion and exclusion criteria are so limiting, the conditions of treatment administration are so optimized, and the results are so narrowly defined that it is difficult to generalize them (Norquist, Lebowitz, & Hyman, 1999).