Estrogen Therapy may not be effective for Schizophrenia
Too little evidence exists to recommend or rule out estrogen as a treatment for schizophrenia in women, a new review of studies finds.
People diagnosed with schizophrenia suffer distorted perceptions of reality and hallucinations. Today, estrogen is strictly an experimental therapy for the psychotic symptoms associated with the mental illness.
Scientists began testing estrogen - a female hormone - as a possible schizophrenia treatment after observing that women with schizophrenia generally fare better than men. Health professionals also noticed that women suffering from schizophrenia seemed more vulnerable to psychotic symptoms during life phases associated with dips in estrogen levels - after childbirth and during menopause.
So far those observations have not been corroborated with solid science, said lead review author Dr. Wan Lian Chua.
"We need to see better quality data. There is further data out there, we just don't have access to it yet," said Chua, a psychiatrist working for the Bradford District Care Trust, an organization in National Health Service, United Kingdom.
The review appears in the most recent issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates medical research. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing medical trials on a topic.
The outcomes for women who received estrogen therapy were not significantly different from the outcomes for patients who did not, Chua said.
The reviewers found just five studies that met their qualifications for inclusion in the meta-analysis. All of the trials were small - from 12 to 42 women studied - for a total of 122 patients included in the review. Chua said the individual trials were "underpowered," that is, they had too few subjects to observe the difference the scientists were looking for.
Psychiatrist Mary Seeman, a professor at Canada's University of Toronto, said those small sample sizes and a string of other complications make the existing body of estrogen-schizophrenia studies methodologically weak.
Most estrogen-schizophrenia trials have only tested the hormone as adjunctive therapy - added on to standard medication for schizophrenia, Seeman said. And none of the studies lasted for very long, she added.
"It's hard to show any effect in the short term," Seeman said. Schizophrenia is a long-term illness, she said, so medicine needs a treatment that can help control psychotic symptoms over the long term.
But as a long-term therapy, estrogen has fallen into disfavor, Seeman said. Studies of hormone-replacement therapy found that long-term estrogen use can spike a women's risk of heart attack, stroke or ovarian and breast cancer.
The Cochrane review recommends that relevant data from completed but unpublished trials - which were not available to Chua and her team - be analyzed before additional studies are mounted. It is a significant body of data, Chua said, that should be used to guide decisions on further trials, because of the risks associated with long-term estrogen therapy.
But Seeman - who was not involved in the systematic review - takes a step further. She said the risks of long-term estrogen use should exclude the hormone as a schizophrenia treatment.
Seeman said future investigation of the possible estrogen-schizophrenia link might focus on a class of drugs called selective estrogen receptor modulators, or SERMs. The drugs stimulate estrogen receptors in certain parts of the body while bypassing other estrogen receptors.
"You would want a drug that activates one of the two kinds of estrogen receptors in the brain, but does not work on the estrogen receptors in the uterus and breast," she said.