Korean Journal of Biological Psychiatry

Objective：There are four possible explanations for the sexual dysfunction of schizophrenics. The first is the possibility of a real structural aspect. The second possibility is that sexual function changes secondary to the illness. The third possibility is that there are medical and sociocultural barriers to sexual expression for chronic schizophrenics. The fourth possibility is that sexual dysfunction due to antipsychotic medication. However, we didn't know the precise cause of sexual dysfunction in schizophrenics. Therefore, the purpose of this study was to explore the mechanism of illness itself and antipsychotics on sexual dysfunction in male schizophrenics.

Methods：The serum prolactin(PRL), testosterone(TST), and the plasma serotonin(5-HT) concentrations were measured by radioimmunoassay and high performance liquid chromatography method for 100 healthy male schizophrenics according to the DSM-IV. Concomitantly, the severity of psychotic symptoms using Clinical Global Impression(CGI), Brief Psychiatric Rating Scale(BPRS), Positive and Negative Syndrome Scale(PANSS), and the severity of side effects for antipsychotics using Extrapyramidal Side Effects Scale(EPSE), Anticholinergic Side Effects Scale(ACSE), the cognitive function using PANSS-Cognitive Function(PANSS-CF), Mini Mental State Exam-Korean(MMSE-K), and the sexual dysfunction using Sexual Functioning Questionnaire(SFQ), Questionnaire for Sexual Dysfunction in Men were assessed. The PRL, TST, and 5-HT levels of 50 healthy male controls who had no medical, neurological, and psychiatric illnesses were evaluated. The sexual function using SFQ(items FGa, FNa) were also assessed. Furthermore, the correlation with age, education, religion, economic status, age at onset, duration of illnesses, duration of admission, levels of PRL, TST, 5-HT, antipsychotic dosages, potency, benztropine, total duration of medication, EPSE, ACSE, CGI, BPRS, PANSS, PANSS-CF, MMSE-K and sexual dysfunctions were identified in male schizophrenics.

Results：1) The frequencies of sexual dysfunctions for schizophrenics(80%) were significantly(p<0.001) higher than those for controls(42%). The sexual dysfunctions according to sexual response cycle were ‘low sexual desire’76%, ‘impairment of achieving erection’75%, ‘impairment of maintaining erection’75%, ‘impairment of obtaining orgasm’32%, ‘impairment in the quality of orgasm’61%, ‘impairment in quantity of ejaculate’44%, ‘premature ejaculation’15%, and ‘delayed ejaculation’50%. 2) The PRL, 5-HT levels of schizophrenics(28.5±20.6ng/ml, 298.5±89.1ng/ml) were significantly(p<0.001) higher than those of controls(10±5.6ng/ml, 169.2±37.8ng/ml), while the TST levels of schizophrenics(4.3±1.5ng/ml) and controls(4.5±1.2ng/ml) were not significantly different. The sexual dysfunctions of schizophrenics who had abnormal 5-HT levels(4.7±1.3 scores) were significantly(p<0.05) higher than those of who had normal 5-HT levels(3.8±1.6 scores) on item D7. 3) The sexual dysfunctions of unmarried schizophrenics were significantly(p<0.01：p<0.05) higher than those of married schizophrenics(6.1±2.8 scores, 4.7±1.3 scores on item FGa：β＝-0.211 on item FNa). The sexual dysfunctions were positively correlated with the rise of 5-HT levels(r＝0.209, p<0.05 on item D4 and r＝0.241, p<0.05 on item D7), the higher age at onset(r＝0.275, p<0.01 on item FNa：r＝-0.202, p<0.05 on item FDa), the longer duration of illnesses(r＝0.237, p<0.05 on item D6), the longer duration of admission(r＝0.234, p<0.05 on item D4：r＝0.328, p<0.05 on item D6), the longer total duration of medication(r＝0.237, p<0.05 on item D6). However, age, education, religion, economic status, PRL, TST levels, antipsychotics dosage, potency, benztropine, ACSE, CGI, BPRS, PANSS, PANSS-CF, MMSE-K scores were not correlated with increased sexual dysfunctions.

Conclusions：Male schizophrenics have significantly more sexual dysfunction to compare with controls. The higher frequencies of sexual dysfunctions were low sexual desire and erectile disorder. The unmarried, higher age at onset, and longer duration of diseases were positively correlated with increased sexual dysfunctions. Also high 5-HT levels were positively correlated with increased sexual dysfunctions. This means that studies of plasma 5-HT levels, albeit questionable indicators of central 5-HT function, offer some additional support for the association of sexual dysfunction with excess 5-HT activity as primary pathology of schizophrenia. Our findings suggest that excess 5-HT activity seems to affect the patient's sexual function.

Keywords Male schizophrenics;Sexual dysfunctions;Serotonin;Prolactin;Testosterone.