Are women born to be grumpy? This sounds like the sexist moan of a disgruntled husband, torn off a strip for failing to put the rubbish out. Again.
Except that science now seems to back the idea that women’s brains may be wired for increased anxiety, depression and mood swings. And the problem could be exacerbated by those high-protein, low-calorie weight-loss programmes (such as the Dukan Diet).
It’s long been known that women suffer more from depression, or at least reported depression. Around one in four women will be treated for depression at some point, compared with one in ten men.
This had been explained partly by social factors — women are more likely to seek help for their symptoms compared with men. However, a recent study from Sweden has discovered two key differences in the way men and women’s brains process serotonin, the so-called ‘happy hormone’.
Good levels of serotonin induce feelings of contentment, reduce appetite and improve sleep. Low levels are associated with depression. It’s this rudimentary understanding of serotonin that led to the development and promotion of antidepressants by drug companies.
Now scientists from the Karolinksa Institute in Sweden have been using brain scans to investigate serotonin levels. And the news is not so cheering for women.
The researchers looked at serotonin uptake — that is, how much serotonin is actually used by the brain — in men and women. Their scans showed women have more serotonin receptors than men.
Every cell in your body has receptor sites on its surface. These are the cellular equivalent of motorway service stations, where you can refuel your cells. Only, instead of petrol or Ginster’s pasties, cell receptor sites allow substances such as nutrients and hormones in and out.
In the case of serotonin, how happy you feel is dependent not just on how much serotonin you make, but on there being sufficient receptor sites in the brain to make it work.
The fact that the women in the Swedish study had more serotonin receptor sites sounds like good news. So, too, does the other finding, which was that women had lower levels of a protein that ‘mops up’ used serotonin.
This means your old serotonin will continue to circulate, bumping up the general level, making you feel happier.
So not only do women have more places in the brain that can be activated by serotonin, but they seem to be able to hold on to it longer. Or so it seems.
In fact, the Swedish research suggests something else. When cells are short of a chemical, such as serotonin, they open up as many receptor sites as possible to ‘catch’ every morsel.
The cells that need it increase their number of receptors to try to make the most of the little that is available. It’s a bit like tipping your bowl to catch every last drop of an especially delicious soup.
For women to have more serotonin receptor sites and be holding on to available serotonin longer seems to indicate they had too little available in the first place.
Other research backs up this idea that women make less serotonin than men. Scientists at the University of Montreal found that men’s brains, on average, make 52 per cent more than women. The reason may be tied to differences in male and female sex hormones.
While the findings about women producing less serotonin are controversial, ‘oestrogen and testosterone, the main sex steroid hormones, have long been known to affect behaviour’, according to the British Society for Neuroendocrinology.
However, oestrogen can have a bigger effect on women due to their ever-fluctuating hormone levels, says Dr Andrei Novac, clinical professor of psychiatry at the University of California Irvine School of Medicine.
Oestrogen specifically ‘stimulates serotonin receptors in the brain’, he explains.
When hormone levels fluctuate, the brain’s sensitivity to serotonin changes, so the amount you needed before may no longer be enough — in effect, the hormones have tinkered with the wiring.
This could explain why women’s serotonin levels ‘drop off’ when their oestrogen levels are low — specifically in the days running up to their period (a major factor in PMS ‘blues’), after childbirth and at the menopause.
And the problem is that this effect is cumulative. As well as fluctuating hormones, women may experience more stress and trauma during a lifetime (due to a variety of events in everyday life).
Over time, this chips away at the ability of the brain and adrenal glands to regulate mood and sexuality, making women more prone to depression.
‘Insufficient levels of oestrogen can create depression — we know that’s why so many women going through the menopause suffer from it,’ says Dr Novac.
So what should women, especially those who suffer from PMS, have just had a baby or are approaching the menopause, do to feel less grumpy and low?
If they are antidepressants are considered inappropriate, lifestyle changes can help, as stress, poor diet and a lack of exercise (and even a lack of sunlight) are all thought to deplete serotonin.
Eating protein, such as turkey or cottage cheese, which are high in tryptophan, an amino acid that the body uses to manufacture serotonin, could also be helpful. But don’t go overboard on protein — and don’t cut the calories.
Researchers from Oxford University found that three weeks of calorie restriction depleted tryptophan levels in both sexes, but especially in women. Diets really do make women grumpier.
But high-protein diets may be especially problematic because although tryptophan is made from protein, for it to ‘work’ it has to get to the brain via the blood and compete for its place against other amino acids.
The most effective way to boost tryptophan in the brain is to eat carbohydrate foods, which stimulate the release of insulin. This clears the competing amino acids from the blood, allowing more tryptophan to enter the brain.
This may explain why women tend to be greater chocoholics than men, especially before a period when oestrogen is low, or during perimenopause. They are self-medicating with carbohydrates to raise their serotonin to stave off the grumps.
And if you are on a high-protein diet, such as the Dukan Diet, have one or two ‘free’ high-carb meals a week to lift your mood.
In her book, Potatoes Not Prozac, nutritionist Kathleen Des Maisons recommends another way to boost serotonin levels — eating a plain baked potato before bedtime.