How could a connection between your brain and immune system impact your multiple sclerosis? We take a look. | Living Like Youread more
Surface sprays, anti-bacterial wipes, hand sanitiser… most of us do all we can to keep germs at bay and avoid the getting sick. But what if our obsession with cleanliness could actually be having the opposite effect on our health?
There’s a theory that over-sanitation has lead to an increase in incidence of allergic and autoimmune disorders in the developed world. The idea was first put forward by a British scientist named David Strachan, who noticed that the more older siblings a child had, the less likely he or she was to develop hay fever. This observation became the basis for the so-called ‘hygiene hypothesis’, the idea that thanks to over sanitation, we’re no longer exposed to infections, parasites and micro-organisms that would otherwise help to prime our immune system – without this exposure, the immune system fails to develop fully and becomes overly sensitive, leading to increased risk of allergies and autoimmune diseases in later life.
While this is now a widely accepted theory, the connection between excessive hygiene and MS hasn’t been investigated until relatively recently. In one study in Norway, 1,846 people (756 of whom had MS) were asked to fill in questionnaires about their childhood, covering everything from whether or not their parents smoked, to any infections they’d had and whether or not they had pets. Interestingly, owning a cat as a child was associated with a greatly reduced risk of developing MS in later life. The researchers concluded this was consistent with the hygiene hypothesis, since cats bring with them a number of micro-organisms that may well help prime the immune system.
So should we all rush out and buy a kitten? Not yet (well, unless it’s to try and make millions by posting cute videos on the internet). Bear in mind that this is only a statistical association – we don’t know for sure that there’s a direct cause and effect. There’s also the fact that if you have allergies then a fluffy feline would be the worst thing to invite into your home, no matter how adorable!
Another study that appears to back up the hygiene hypothesis for MS found that women with the common gut infection Helicobacter pylori (H. pylori) were less likely to develop MS than those without these bacteria. But rather than H. pylori itself being protective in some way, the researchers suggest that H. pylori infection indicates exposure to infections in general, which helped to desensitise the immune system and reduce risk of MS.
The hygiene hypothesis may even help to explain the geographical prevalence of MS. We know for example, that the incidence of MS increases the further away you get from the equator. As we’ve talked about before on Living Like You, there’s a well-known theory that vitamin D levels drop with decrease in sunlight hours, and it’s low levels of vitamin D that affect the immune system. However, perhaps sanitation also plays a role. Incidence of MS is increasing in the developed world, where rates of infectious diseases have been greatly reduced thanks to improved hygiene. In tropical countries, on the other hand, where sanitation is generally lower and infectious diseases more rife, the incidence of MS remains relatively low.
Of course, none of this is helpful if you already have MS – you can’t go back and change your childhood, after all, and eating mud now wouldn’t have quite the same effect. That said, munching a few worms might…
Yes, really. Understanding the link between hygiene and autoimmune diseases has led some researchers to pursue some interesting new therapies for MS. One of these is parasite therapy, which is every bit as icky as the name suggests. Studies show MS is less frequent in people infected with worm-like parasites called helminths. What’s more, mice that have been colonised with helminths show protection against the disease. Now scientists are looking into whether or not infecting people who have MS with helminths could help to regulate the immune system in some way. Clinical trials are underway in the US, Britain, Germany and Denmark in order to investigate this; so far these studies have been small, but results have been encouraging. Patients treated with pig whipworms, in one small study in America, for example, showed a marked reduction in brain lesion size. More research is needed, but this is certainly an exciting (and often skin-crawling) new development in immune therapy.
While it’s true that excessive hygiene may have increased the incidence of certain autoimmune diseases, we definitely don’t want to imply that it’s all bad. Improvements in hygiene have also lowered the risk of a number of deadly diseases and that has made a fundamental difference to critical things like infant mortality rates, to name just one. The challenge now is to understand how our changing hygiene habits have affected the delicate balance of micro-organisms in the body and to somehow redress this.
In the future this may mean children pop a daily pill containing small doses of helpful micro-organisms to prime the immune system – many of us already take probiotics to replenish levels of friendly bacteria in the gut. Or at least, people might go back to the good old soap-and-water combo more often instead of all those antibacterial soaps and detergents that are out there. These antibacterial agents might anyway not be always advantageous as studies have shown no added benefit of those to prevent for example gastrointestinal illnesses but on the other hand they are suspected to contribute to the emergence of antibiotic-resistant bacteria.
Whatever the case, there’s no need to let your hygiene standards slip just yet. So if you were looking for an excuse to get out of cleaning the bathroom, this isn’t it!