Research Notes

An Herbal Cure for PMS? Approaches to treating premenstrual syndrome (PMS) include taking selective serotonin reuptake inhibitors such as Prozac, rubbing in progesterone creams, and eating more essential fatty acids, all of which are of questionable efficacy. An Internet search turns up the usual "food supplement" remedies. "Herbal solace," for example, offers as a main ingredient phenylalinine, an "element" that is found naturally in some plants and animals. This makes some sense, for phenylalinine begets tyrosine, which begets the mood-stabilizing serotonin. The product also provides extracts of wild yam, licorice root, juniper berry, red raspberry leaf, valerian root, ginger root, and a few other items. Not in the recipe, however, is extract of Vitex agnus castus, or the chasteberry tree, for its inhibiting effects on the libido. Known in health food circles as agnus castus, this plant contains various flavonoids, glycosides, and compounds related to our own sex hormones. A randomized, double-blinded test of extract of its dried fruits suggests that it may alleviate some of the symptoms of PMS. "Agnus castus is known to be effective in treatment of PMS, but there does not exist a large, placebo-controlled clinical study. This study showed that the experience [of symptom improvement] is not a simple placebo effect," says Ruediger Schellenberg, senior consultant at the Institute for Health Care and Science in Huttenberg, Germany (R. Schellenberg, "Treatment for the premenstrual syndrome with agnus castus fruit extract: prospective, randomised, placebo controlled study. British Medical Journal, 322:134-7, Jan. 20, 2001. www.bmj.com/egi/content/full/322/7279/134) Schellenberg and colleagues followed 170 women through three menstrual cycles, 86 receiving the plant extract in pill form, and 84 receiving placebo. The participants were asked to rate six symptoms of PMS, before and after the trial: irritability, mood alteration, anger, headache, breast fullness, and bloating. For all symptoms except bloating, those receiving the extract reported marked improvement. Although he's still working on deciphering the mechanism of this apparent therapeutic action, Schellenberg suggests that in the meantime, agnus castus be considered a good treatment for PMS. For the 3-5 percent of PMS sufferers who have the more debilitating "premenstrual dysphoric disorder" as described in the Diagnostic and Statistical Manual IV, this will be welcome news. --Ricki Lewis Bacteria Jumpstart Wasp Speciation The road to speciation need not require an event as tumultuous as the rise of a mountain range or the creation of islands. Bacterial infection may do the trick, finds a research team from the University of Rochester. The culprit: Wolbachia, a type of bacterium widespread in the invertebrate world. In certain fruit flies, flour beetles, and parasitic wasps, infected males cannot produce offspring with females that are not also infected, a phenomenon called cytoplasmic incompatibility. In such a doomed mating, chromosomes from the sperm are preferentially lost shortly after fertilization. Professor of biology John Werren and undergraduates Seth Bordenstein and Patrick O'Hara assessed fertility and infection status among two very closely related species of wasp, Nasonia giraulti, a resident of the eastern United States and Canada, and N. longicornis, from the west (S.R. Bordenstein et al, "Wolbachia-induced incompatibility precedes other hybrid incompatibilities in Nasonia," Nature, 409:707-10, Feb. 8, 2001). When Wolbachia is present, interspecific hybrids do not result, but when antibiotics kill the bacteria, hybrids survive. Therefore, bacterial infection restricts reproduction, perhaps setting the stage for the genetic divergence that fuels speciation. Their work augments earlier experiments on two more distantly related wasp species, where other signs of speciation occur (J.A. Breeuwer, J.H. Werren, "Microorganisms associated with chromosome destruction and reproductive isolation between two insect species," Nature, 346:558-60, 1990). "In the older species pair, bacterial infection leads to complete reproductive incompatibility, as well as other problems, such as high mortality in the offspring of the offspring, and behavioral changes in these males so that they cannot court. This indicates that genes in the two species diverged to the point where they did not get along well enough to produce functional offspring," explains Werren. When antibiotics were applied to these older species, the second-generation problems persisted. In contrast, the more recently diverged species, when given antibiotics, did not display other problems. The role of infection in early speciation, a controversial idea, does not preclude better-known routes. Concludes Werren, "The key to speciation is reproductive isolation that allows populations to diversify. This is a new mechanism to decrease gene flow in an incipient [newly evolving] species. It increases the chance of divergence." --Ricki Lewis Report on Brain's Role in Violence Biomedical research into violent behavior has been relatively neglected when compared to the extensive efforts devoted by the social sciences, according to a consensus report published in the current issue of Neuropsychiatry, Neuropsychology and Behavioral Neurology (C.M. Filley et al., "Toward an understanding of violence: neurobehavioral aspects of unwarranted physical aggression: aspen neurobehavioral conference consensus statement," 14[1]:1, January 2001). The report called for increased research into the role of the brain in violent behavior, and particularly for a large-scale, longitudinal study of the neurobehavioral aspects of violence. A study of individual perpetrators of violence is critical to deeper understanding of the causes and solutions of violence, said Bruce Price, chief of neurology at McLean Hospital in Boston, Mass., and one of the authors on the report. While social influences certainly play a primary role, an estimated 10 to 20 percent of impulsive crimes can be attributed to brain damage, Price said. "Brain science may not answer all the problems, but the hope is that if we can identify relative risk factors, particularly at early life, we can, by intervention, steer people toward less violent behavior," he said. Violent behavior has been linked to frontal lobe dysfunction, altered serotonin metabolism, and genetic influences, according to the consensus report, which was authored by a multidisciplinary group representing neurology, neuropsychology, psychiatry, trauma surgery, nursing, evolutionary psychology, medical ethics and law. --Jennifer Fisher Wilson

Research Notes

An Herbal Cure for PMS?

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