Six Month, Double Blind, Placebo-controlled Trial of the Efficacy of Raloxifene as an Adjuvant Treatment of the Negative Symptoms of Schizophrenia in Post-menopausal Women

Several studies have found gender-related differences in the epidemiology, clinical presentation, clinical course and response to treatment of schizophrenic disorder(1,2). Findings relating to a lower frequency of schizophrenia in women, its later onset and less severe clinical course(3,4), have led to the appearance of the "estrogen hypothesis" of schizophrenia, which postulates that estrogen has a protective effect in women susceptible to this disease(5).

The estrogen hypothesis in relation to schizophrenia is based on several studies that showed that estrogen levels are significantly lower in schizophrenic women than in healthy women,(6) and that outbreaks or onset of the disease tend to coincide with stages of the menstrual cycle in which estrogen levels are the lowest(7,8).

Studies on experimental animals have shown that estrogen has a modulating effect on the brain dopaminergic system(9,10) and that it also affects serotoninergic activity(11). Estrogens also enhance neuronal regeneration and block mechanisms of neuronal death(12).

The discovery that estrogen has a modulatory effect on the dopaminergic system has encouraged some researchers to study the therapeutic use of estrogen in schizophrenic patients. Several double-blind clinical trials have shown that estrogens are effective at improving psychotic symptoms(13-15). These last studies analyzed the efficacy of estrogens after one and two months, and mainly in relation to positive symptoms, in patients with the acute illness. However, in older patients it is the severity of the negative, rather than the positive, symptoms that seems to be associated with a poorer cognitive and social function. Moreover, positive symptoms tend to be less severe with age, while negative symptoms tend to persist(16).

Regarding the possible use of estrogens to treat post-menopausal women with schizophrenia, Lindamer et al.,(17) studied the psychopathology of menopausal patients with schizophrenia and found that patients in hormone replacement therapy required lower doses of antipsychotic drugs and presented less negative symptoms, whereas no differences were found in response to treatment in relation to positive symptoms.