Moody men blame their hormones

Alf Garnett - the original grumpy, irritable man

Scientists may have come up with an explanation for why men become grumpy and irritable.

They can't help it - they are just suffering from "irritable male syndrome".

Men's mood swings may be down to a sudden drop in the male hormone testosterone which, the theory says, affects their brain and therefore behaviour.

Some scientists believe that middle-aged men go through a menopause, as women do.

But Gerald Lincoln of the Medical Research Council's Human Reproductive Sciences Unit in Edinburgh believes stress can cause men of any age to suffer testosterone levels to plummet, affecting their mood and behaviour.

It is difficult to tie in mood with hormone levels, because mood is a very subjective thing

Dr Ian Banks, Men's Health Forum

Although very little work has looked at the relationship in humans between stress and testosterone, many studies in animals, including primates, show that testosterone levels fall when stress increases levels of a hormone called corticosteroid.

Dr Lincoln, whose work is featured in New Scientist, first identified irritable male syndrome in Soay sheep.

In autumn, rams' testosterone levels soar and they mate. In the winter, testosterone levels fall and they lose interest in sex.

He found that even though testosterone is supposed to be linked to more aggressive behaviour, the rams were more likely to injure themselves when their levels of the hormone were low.

Sheep study

Dr Lincoln followed the behaviour of eight rams, including how often they struck out with their horns.

He found that as testosterone levels fell, rams became nervous and withdrawn, striking out irrationally.

Dr Lincoln has observed similar changes in behaviour in red deer, reindeer, mouflon and Indian elephants.

In human males, it is suggested a drop in the hormone is significant because the brain is loaded with receptors for testosterone and its conversion products, which will be affected if levels fall.

Dr Lincoln told BBC News Online: "We're trying to redress the balance. This phenomenon is well described in women because of their cyclic biology".

But he said men's hormone drops were linked to stressful experiences such as bereavement, divorce or life-threatening illnesses could affect testosterone levels.

Dr Lincoln said antidepressants may be able to help some men, but that it was crucial to recognise irritable male syndrome existed so that more research could be carried out into the condition

Division

Experts are divided over Dr Lincoln's theory.

Richard Anderson, who is also at the Edinburgh unit, 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.

And David Abbott of the Wisconsin Regional Primate Research Center in Madison said: "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."

David Handelsman, an expert on male hormones at the University of Sydney, said changes in testosterone levels in normal adult men are far smaller than the dramatic swings seen in the Soay rams.

However, in men who are castrated as treatment for advanced prostate cancer, levels fall by at least 90% and men become more withdrawn, but more emotional.

Dr Ian Banks, president of the Men's Health Forum was also cautious: "It is difficult to tie in mood with hormone levels, because mood is a very subjective thing."

He added that although there was an increasing awareness of the impact of testosterone, there was not a universal agreement that men experienced their version of a menopause.