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Men behaving badly

February 27, 2002

BAD-TEMPERED? Nervous? Easily reduced to tears? If you are a man, you could be suffering from irritable male syndrome.

        This newly recognised condition plays havoc with male animals, temporarily turning confident, chest-beating Tarzans into withdrawn, grumpy wimps. And there`s some evidence that irritable male syndrome, which is triggered by a sudden drop in testosterone, affects men as well as animals, says Gerald Lincoln of the Medical Research Council`s Human Reproductive Sciences Unit in Edinburgh.

        The symptoms may resemble those of the so-called male menopause, but Lincoln believes the condition can affect men of any age when stress causes testosterone levels to plummet. If he`s right, it`s not just women who have their hormonal ups and downs.

        Lincoln first pinpointed the syndrome in Soay sheep. In the autumn, the rams` testosterone levels soar and they rut. In the winter, testosterone levels plummet and they lose interest in sex. High testosterone is supposed to mean more aggression. But the rams were more likely to injure themselves when testosterone was low.

        So Lincoln monitored the activity of eight rams, such as how often they struck out with their horns. As testosterone levels fell, the rams changed from competent males who addressed each other in a ritualistic fashion, to nervous, withdrawn animals that struck out irrationally, he says.

        Red deer, reindeer, mouflon and Indian elephants also show clear signs of irritable male syndrome when testosterone levels fall off at the end of their breeding seasons, says Lincoln. "The mahouts sometimes starve the elephants after the must, or tie them up to keep them under control."
        But what does this mean for people? Here the evidence is shaky, Lincoln admits. But it`s clear that testosterone has a major impact on human behaviour. The brain is loaded with receptors for testosterone and its conversion products. What`s more, Richard Anderson, also at Edinburgh, has found that when men who cannot produce testosterone come off hormone replacement therapy, they become irritable and depressed. Their mood improves when they resume treatment.

        Lincoln thinks that stresses such as bereavement, divorce or life-threatening illnesses could send testosterone levels plummeting. There are few human studies on stress and testosterone, he says, but numerous studies on animals, including primates, show that testosterone levels fall when stress sends corticosteroid levels skywards.

        "It`s right on the money," says reproductive endocrinologist David Abbott of the Wisconsin Regional Primate Research Center in Madison. "Testosterone effects have been missed. When a bloke gets grumpy and irritable, [researchers] try and explain it only in terms of cortisol levels and depression. They ignore the fact that testosterone levels are probably falling too."

        But David Handelsman, an expert on male hormones at the University of Sydney, is more cautious. He says the changes in testosterone levels in normal adult men are far smaller than the dramatic swings seen in Soay rams, with one notable exception: levels fall by at least 90 per cent in men who undergo castration for advanced prostate cancer. "The wives notice it first," says Keen-Hun Tai of the Peter MacCallum Cancer Institute in Melbourne. "The men become more withdrawn, but more emotional. They laugh and cry more easily."

        Clearly, the jury`s still out when it comes to people. But if irritable male syndrome does affect men, diagnosing it won`t be easy. It`s far from clear what normal testosterone levels are (see New Scientist, 22 July 2000, p 36), while extra doses of the hormone may increase the risk of heart disease.

        But the syndrome could still be worth investigating. "Instead of putting stressed men on Prozac, a little testosterone may do the job," says Abbott.
Author: Rachel Nowak, Melbourne

More at: Reproduction, Fertility and Development (vol 13, p 567)
http://www.newscientist.com">New Scientist issue 2nd March 2002


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