Oh the brain freeze will blind the weary runner

Like a cold chisel to the head, ice cream headaches are an unfortunate side-effect of what is otherwise a pleasant relief and an effective way to improve athletic performance in hot weather, as suggested by recent research.

Let me explain. (And let me also apologise for my attempted pun, which I blame on summer brain deactivation.)

An ice cream headache, also known as brain freeze or cold stimulus headache, or, if you want to get really fancy, sphenopalatine ganglioneuralgia, is the pain you get when something very cold touches the roof of your mouth.

It is supposedly the most common cause of head pain; at least, according to the seminal 1988 textbook Headache, by Dr Neil H. Raskin. Although, Dr Raskin also found it was more common in migraine sufferers, with 93% of them experiencing it compared to 31% of a control group (see the reassuringly titled article by Joseph Hulihan in the British Medical Journal, “Ice cream headache: no need for abstinence” [PDF 159 KB]).

The pain appears to start in blood vessels in the mouth or sinuses, which rapidly contract when cooled and then dilate again when they rewarm. It’s then transmitted to the brain by either the trigeminal, glossopharyngeal or vagus nerve (opinions are divided on the culprit).

The trigeminal nerve, shown in yellow, carries signals between the brain and most parts of the face. The glossopharyngeal and vagus nerves, not shown, largely serve the throat and chest, respectively. (Gray's Anatomy of the Human Body, 20th edition)

The problem is that each of these nerves serves many other parts of the head – like the forehead in the case of the trigeminal, or the membrane around the brain for the glossopharyngeal – and the brain misinterprets the signals as coming from one of these other areas. This is a phenomenon known as referred pain, which can also be experienced in heart attacks when people feel pain in the neck, shoulders or back instead of the chest.

There are a few treatments recommended for ice cream headaches, like tilting your head back, pressing your tongue against the roof or your mouth or drinking a warm drink. But for most people they’ll go away themselves some time between 20 seconds and 5 minutes – although for an unfortunate few they’ve been known to trigger migraines.

But as I mentioned before, it’s also the main drawback for a newly “discovered” method athletes can use to stave off overheating. Drinking “ice slurry” – basically slurpies – allows people to run for longer in hot weather and endure a higher body temperature, compared to those who only have a cool drink (Siegel R, Maté J, Brearley MB, Watson G, Nosaka K & Laursen PB 2010, “Ice slurry ingestion increases core temperature capacity and running time in the heat”, Medicine & Science in Sports & Exercise, vol. 42, no. 4, pp. 717-725, doi:10.1249/MSS.0b013e3181bf257a).

More recent follow-up research by the same group compared the ice slurry with full body immersion in cold water. Both methods were just as effective in increasing running time, but the slurpies were rather more convenient (Siegel R, Maté J, Watson G, Nosaka K & Laursen PB 2012, “Pre-cooling with ice slurry ingestion leads to similar run times to exhaustion in the heat as cold water immersion”, Journal of Sports Sciences, vol. 30, no. 2, pp. 155-165, doi:10.1080/02640414.2011.625968).

The one problem? 6 out of the 8 participants in the trial suffered from brain freeze.

Which just goes to show that even the most benign, natural-sounding treatments – or in this case, performance-enhancing drugs – can have unfortunate side effects. But still, remember that title from the British Medical Journal: “no need for abstinence”.

Because I don’t pick on The Age enough

While it’s true that in the past I’ve found the Herald Sun to be an easy target, let’s not forget the other Melbourne newspaper.

Browsing The Age website today, I came across the following link to an article in their Executive Style section:

The article itself gives a reasonable precis of the report which it’s quoting (Kim JH, Malhotra R, Chiampas G, d’Hemecourt P, Troyanos C, Cianca J, Smith RN, Wang TJ, Roberts WO, Thompson PD, & Baggish AL 2012, “Cardiac arrest during long-distance running races”, New England Journal of Medicine, no. 366, pp, 130-140, doi:10.1056/NEJMoa1106468).

Specifically, it repeats the article’s main conclusions, which are:

Marathons and half-marathons are associated with a low overall risk of cardiac arrest and sudden death. Cardiac arrest, most commonly attributable to hypertrophic cardiomyopathy or atherosclerotic coronary disease, occurs primarily among male marathon participants; the incidence rate in this group increased during the past decade.

That increase there being due to the greater number of people participating in marathons and half-marathons.

My concern is of course the sensationalist headline, which tries to emphasise the fear that running is in fact dangerous. A message somewhat at odds with the media releases from the institutions where the research was based, being the Massachusetts General Hospital and Harvard University. Their stories were, respectively, Participating in marathons, half-marathons not found to increase risk of cardiac arrest and Good news for marathoners.

What have we learned here? I can think of at least two things:

1. Never treat a newspaper headline as an accurate summary of scientific research; always read the actual story carefully, or preferably track down the original article.
2. Whatever you may think of the paper itself, don’t assume newspaper websites are a reputable news source.

Recently on the radio

We’ve been a bit quiet recently on the Lost in Science blog. But that doesn’t mean the team hasn’t been busy, oh no!

Here are some links to go with our recent radio broadcasts. Or, you can download the podcasts, for our shows from 3 November 2011 (25:54 min / 12 MB) and 10 November 2011 (28:09 min / 26 MB).

• Analysis of corporate ownership networks shows that out of 43,060 transnational companies, only 147 of them – mostly banks – control 40% of the wealth. Read more in New Scientist, or see the entire paper in the arXiv database.
• Protesting about this risks exposure to pepper spray, or Oleoresin Capsicum, which uses the chemical capsaicin ((CH₃)₂CHCH=CH(CH₂)₄CONHCH₂C₆H₃-4-(OH)-3-(OCH₃)), extracted from chilli peppers, to cause eye and skin irritation. Read about its health effects in Investigative Opthalmology and Visual Science and the North Carolina Medical Journal, or see treatment recommendations from Melbourne’s Royal Children’s Hospital.
• The Berkeley Earth Surface Temperature study, partly composed of and funded by climate change sceptics, has performed a massive re-analysis of global land temperature records and verified that yes, the world really is warming.
• Aside from being real, climate change seems to have caused Australian seaweed species to move between 50 and 200 km south, risking the habitat of many other species that depend on them. Read more at ABC Science, or see the paper in Current Biology.
• In more extinction news, Tasmanian devils are currently threatened by a contagious cancer, which seems to spread due to their genetic similarity. Hope is held for a small, genetically different and mostly disease-free population in the northwest of the state, research into which has won a team of scientists the 2011 Eureka Prize for Environmental Research (also see their paper in Conservation Biology). Although the recent discovery of devils with facial tumour disease in even that remote area has increased concern for this unique species.
• (A good friend of ours, John Cook of Skeptical Science, was also awarded the 2011 Eureka Prize for Advancement of Climate Change Knowledge. Congratulations John!)
• Speaking of genetic diversity, research on the Sandy Island mouse has shown that polygamous females produce more viable embryos. See the paper in Ecology Letters, or read more at the University of Western Australia.
• Finally, to space. Three recent discoveries have shed new light on how solar systems like ours form: there’s a planet called LkCa 15b, 473 light years away, which has been discovered in the process of forming; water seen in the planet-forming disk around the young star TW Hydrae (175 light years away) supports the theory that it collects around grains of dust to make comets, which then deposit the water on planets like Earth; and photos of the asteroid Lutetia, taken by the European Space Agency’s Rosetta probe, suggest that, at around 3.6 billion years old it’s a relic of the early Solar System, and have given clues to its formation.

Have you missed any other shows? Catch up on our old episodes!

Vaccines vs malaria, Michele Bachmann, other diseases

There was great medical news for the world this week, with the announcement of the successful trial of a vaccine for malaria (The RTS,S Clinical Trials Partnership, “First results of phase 3 trial of RTS,S/AS01 malaria vaccine in African children”, The New England Journal of Medicine, October 18, 2011, 10.1056/NEJMoa1102287).

This trial, involving 15,460 babies and children, found the vaccine known as RTS,S gave 50% protection against the disease. Given that malaria kills about 800,00 people annually – mostly small children in Africa – that’s an incredible number of lives that could be saved.

It’s an incredible scientific achievement too, given that this is the first time a vaccine has been effective against a parasite, rather than a virus or bacteria.

And of course, given the number of other diseases that have already been tackled by vaccines, millions of lives have already been saved since Edward Jenner’s first smallpox vaccination, in 1796.

But right from the start, campaigns to vaccinate – and especially to make it compulsory – have been met by campaigns against vaccination.

Anti-vaccination movements have many motivations, ranging from concerns about individual liberty to, famously (and famously discredited), fears that they cause autism.

Recently, would-be Republican presidential candidate Michele Bachmann climbed aboard the anti-vaccine bandwagon. Her specific target was Gardasil, vaccine for the human papillomavirus, which is a major cause of cervical cancer.

Her claim, that it causes “mental retardation”, was typical of anti-vaccinationists, and is largely based on confusing coincidence with causation (with any mass-vaccination campaign, bad things are bound to happen to people just by mere chance, but it’s all too easy jump to the conclusion that the events must be connected – call it the human tendency to discern patterns where there are none).

This is not to deny that vaccines need scrutiny; they are usually derived from the pathogen or toxin that causes the disease, so rigorous testing has to be done to ensure their safety. And we rely on government bodies, like the US Food and Drug Administration (FDA), or Australia’s Therapeutic Goods Administration (TGA), to monitor and enforce safety standards.

Of course, this itself is not without controversy: recently there has been a lot of criticism of the TGA for being slow to act on a flu vaccine produced by CSL that caused adverse reactions like fevers and seizures.

The trouble is that these things affect people’s lives, but the science involved isn’t always clear to those people. And so we have to hope that those making decisions are better informed. The lifesaving potential of discoveries like the malaria vaccine is all too easily scuppered by people in power giving in to non-scientific ideas.

And there’s not much more power you can get than the President of the United States…

Weird sigh-ence

We’re all still on a high from the recent Aussie Nobel Prize win, but it’s important not to overlook those other prestigious annual science awards, the IgNobel Prizes.

The 2011 IgNobel Prizes include a couple of Australian winners: Robert Pietrzak, David Darby and Paul Maruff shared the Medicine Prize with other international researchers for studying how needing to wee affects your concentration (see their article in Neurourology and Urodynamics); and Darryl Gwynne and David Rentz took out the Biology Prize for showing that male Buprestid beetles mistake beer bottles for female beetles (and see their article in the Australian Journal of Entomology).

Male Bupestrid beetle attempting to mate with a beer bottle (Photo by Gwynne and Rentz)

There were many other worthy winners, but one that particularly caught my eye was the Psychology Prize, awarded to Norwegian psychologist Karl Halvor Teigen for his work trying to understand why people sigh (Karl Halvor Teigen 2008, “Is a sigh ‘just a sigh’? Sighs as emotional signals and responses to a difficult task”, Scandinavian Journal of Psychology, vol. 49, no. 1, pp. 49–57).

Using a series of questionnaires and practical exercise, what he found was that, although most of us think of sighs as an expression of sadness, they’re actually more associated with a feeling of resignation, like giving up on a frustrating task.

Teigen performed this study to demonstrate to his students that not all questions have been answered. But curiously, since his work was published other researchers have also studied the cause of sighs, only from a physiological perspective (Vlemincxa E, Van Diesta I, Lehrerb PM, Aubertc AE, Van den Bergh O 2010, “Respiratory variability preceding and following sighs: A resetter hypothesis”, Biological Psychology, vol. 84, no. 1, pp. 82-87).

Using a very different method, Vlemincxa et al. got remarkably similar results. After a sequence of irregular breathing – also often associated with a stressful task – the experimental subjects sighed and returned to a more regular breathing pattern. Their hypothesis is that we sigh to “reset” our breathing after stress.

Think about this next time you, or someone else, sighs, and see if it agrees with these studies. And reflect on how right Karl Halvor Teigen really was: it’s still possible to find things in every day life, that we all do, but we don’t fully understand.

Cold facts about ice for injuries

Sprains and other sporting injuries are very common when, like me, you’re an elite athlete. Well, assuming you don’t put much store in the term “elite”.

You see, last week I injured the ring finger on my left hand when goalkeeping in a fiercely fought final of indoor soccer (we lost). And, after running around and yelling a bit, I applied the usual first aid many of us use in these cases: I kept it elevated with an ice pack on it for a long time – pretty much until the ice melted.

Photo of an ice pack, courtesy Wikimedia Commons. I didn't have the foresight to take photos of my injury at the time, and by now there's nothing to see.

Sitting there in this awkward position, I started wondering: is this the right thing to do? What does science have to say about applying ice to injuries?

Well. There haven’t been many studies on the topic, and most of the papers published seem to be from a handful of researchers. But the gist appears to be that ice may help with pain relief, but the evidence is not overwhelming. And it should only be applied intermittently, rather than continuously.

So don’t entirely abandon the standard first-aid approach of RICE - that’s rest, ice, compression and elevation – but don’t rely on ice to be the main component. And, as recommended by the Better Health Channel, apply ice for only 10-15 minutes every 2 hours, separated from the skin by wet towelling.

And of course if it continues to get worse, see your doctor.

Some references on icing injuries, listed from newest to oldest:

• Bleakley CM 2011, “Cooling an acute muscle injury: can basic scientific theory translate into the clinical setting?”, British Journal of Sports Medicine (doi:10.1136/bjsm.2011.086116)
  “Current best evidence shows that muscle temperature reductions in humans are moderate in comparison to most animal models, limiting direct translation to the clinical setting… Contrary to current practice, it is unlikely that a ‘panacea’ cooling dose or duration exists.”
• Collins NC 2007, “Is ice right? Does cryotherapy improve outcome for acute soft tissue injury?”, Emergency Medicine Journal, no. 25, pp. 65-68 (doi:10.1136/emj.2007.051664)
  “There is insufficient evidence to suggest that cryotherapy improves clinical outcome in the management of soft tissue injuries.”
• Ivins D 2006, “Acute ankle sprain: an update”, American Family Physician, vol. 74, no. 10, pp. 1714-1720
  “There is some evidence that applying ice and using nonsteroidal antiinflammatory drugs improves healing and speeds recovery.”
• Bleakley CM, McDonough SM & MacAuley DC 2006, “Cryotherapy for acute ankle sprains: a randomised controlled study of two different icing protocols”, British Journal of Sports Medicine, no. 40, pp. 700-705 (doi:10.1136/bjsm.2006.025932)
  “Intermittent applications may enhance the therapeutic effect of ice in pain relief after acute soft tissue injury.”
• Bleakley C, McDonough S & MacAuley D 2004, “The use of ice in the treatment of acute soft-tissue injury: a systematic review of randomized controlled trials”, American Journal of Sports Medicine,  vol. 32, no. 1, pp. 251-261 (doi: 10.1177/0363546503260757)
  “There was marginal evidence that ice plus exercise is most effective, after ankle sprain and postsurgery. There was little evidence to suggest that the addition of ice to compression had any significant effect, but this was restricted to treatment of hospital inpatients.”
• MacAuley DC 2001, “Ice therapy: how good is the evidence?”, International Journal of Sports Medicine, vol. 22, no. 5, pp. 379-84
  “It is concluded that ice is effective, but should be applied in repeated application of 10 minutes to be most effective, avoid side effects, and prevent possible further injury.”

Glow cats looking for the cure

Cats are stealthy animals, sneaking around at night hunting prey, so glowing in the dark might not seem terribly useful. But if it protects them from cat AIDS, maybe it’s not such a bad thing.

OK, so we’re not talking about ordinary cats. These are transgenic cats, genetically modified organisms that were given a gene from rhesus macaque monkeys that blocks infection by the feline immunodeficiency virus (FIV), a close relative of HIV.

They were also given a jellyfish gene that causes them to glow under ultraviolet light. This makes a handy marker to distinguish cats that are carrying altered genes from those that aren’t.

A transgenic kitten, seen here glowing under ultraviolet light. It's accompanied by a regular, non-fluorescent, control cat (Image from Mayo Clinic)

The big success was that when the cats reproduced, the new genes were passed on to their offspring, creating glow-in-the-dark, FIV-resistant kittens.

Although the technique used to create these fluorescent felines can’t actually be used to treat infected humans or cats, it does point the way for medical – and veterinary – researchers to develop possible gene therapies.

References:

• Wongsrikeao P, Saenz D, Rinkoski T, Otoi T & Poeschla E 2011, “Antiviral restriction factor transgenesis in the domestic cat”, Nature Methods, no. 8, pp. 853–859 (doi:10.1038/nmeth.1703)
• Mayo Clinic teams with glowing cats against AIDS, other diseases.

Funny is the new drug

Reader’s Digest has long told us that laughter is the best medicine, but it turns out it also helps us to cope with pain.

British scientists showed volunteers clips from either comedy programs, like Mr Bean or Friends, or unfunny shows, like golf, or wildlife documentaries. They also found volunteers at the Edinburgh Fringe Festival, and made them watch either stand-up comedy or theatrical drama.

They then exposed the laboratory subjects to mild pain, from a cold wine cooler sleeve on their arm, or a tight blood pressure cuff (the festival goers were given a strenuous physical challenge of leaning against a wall with their legs bent, like sitting on a chair).

What they found was that 15 minutes of laughter was enough to increase the subjects’ level of pain tolerance by 10 per cent. Whereas the serious programs, or dramatic theatre, had no such effect.

If Mr Bean is good for you and golf isn't, then what about Mr Bean playing golf?

The likely explanation is the release of endorphins, which are known to dull the nerve signals associated with pain. Endorphins are typically released by physical exercise, which in this case would be the muscular exertion of repeated, involuntary exhalation of breath that makes up laughter.

But there is one condition: the pain reduction effect only seems to apply with a good, hearty belly laugh, rather than a gentle titter. These big laughs are more likely to happen in groups than to people on their own, which reinforces the idea that laughter is a tool for social bonding.

Who’d have thought Friends represented an evolutionary advance?

Dunbar RIM, Baron R, Frangou A, Pearce E, van Leeuwen EJC, Stow J, Partridge G, MacDonald I, Barra V & van Vugt M, “Social laughter is correlated with an elevated pain threshold”, Proceedings of the Royal Society B, published online before print September 14, 2011, doi: 10.1098/rspb.2011.1373

If it quacks like homeopathy…

There is a lot that can be said about homeopathy, particularly on a science blog like this one. And most of it is not very nice – but I’m going to say it anyway.

To cover the basics, homeopathy was invented by Samuel Hahnemann in 1796, based on the “Law of Similars”, or the idea that “like cures like”. This essentially involves treating disease using substances that cause the same sort of symptoms – except that you dilute it as much as possible, because supposedly if high concentrations cause an illness, then low concentrations must cure it.

(This is something I’ve never understood. Homeopaths like to claim that, unlike regular doctors, they treat the whole person and not just the disease. Yet their remedies are based on merely addressing the symptoms, which is supposed to be more “holistic” than, say, fixing what caused the problem.)

But the concentrations used mean there should be absolutely nothing left of the original substance. For instance, one popular homeopathic remedy for the flu is Oscillococcinum, made from duck organs (yes, really). It’s prepared at what they call 200C, which translates to a concentration of 1 part in 10⁴⁰⁰. To put that in perspective, most estimates put a limit on the number of particles in the entire universe as somewhat less than 10⁸⁷. (The good news is that means it’s probably safe for vegans.)

A duck, whose heart and liver are used to make Oscillococcinum, a homeopathic remedy for cold and flu. Its feathers can also be used. (Photo by H. Zell, via Wikimedia Commons)

Don’t get me started on claims that water has a memory, or that there’s some sort of magical quantum effect. Quantum mechanics may do very strange things that don’t make sense in our familiar macroscopic world, but physicists actually understand it very well. It’s not some magic word you can just use to bluff your way through anything.

But the main point is that it simply doesn’t work: see the reviews from our old friends at the Cochrane Library (and yes, I’m aware of claims that science somehow doesn’t work on homeopathy; but this is a science blog, so I’m going to stick with it).

With all this damning lack of evidence, Australia’s National Health and Medical Research Council (NHMRC) is quite sensibly preparing a statement on homeopathy. According to leaked drafts, they’re likely to conclude that “it is unethical for health practitioners to treat patients using homeopathy, for the reason that homeopathy – as a medicine or procedure – has been shown not to be efficacious.”

And it’s not just the rather amusing scientific reasons listed above that make it unethical, but also the serious fact that people have died after only taking homeopathic remedies for otherwise treatable illnesses: a baby in NSW that died from severe eczema and a WA woman who died of colorectal cancer.

It also follows a similar finding from the UK House of Commons Science and Technology Committee (PDF 1.6 MB).

Unsurpisingly, homeopathy’s supporters are trying to fight this conclusion. The Aurum Project – “commitment to the health and wellbeing of children” – is recommending their followers write to the NHMRC to complain.

Well, why not take their lead but do the opposite? Write to the NHMRC and tell them you support their goals.

After all, the way that science works is that the truth eventually wins out – but it doesn’t hurt to help it along.

Bad mozzies, good bacteria

It’s not often that bacteria actually prevent disease, but that could be the case in North Queensland, where scientists have infected mosquitoes with the bacteria Wolbachia to try and control the spread of dengue fever.

Dengue fever is not yet endemic to northern Australia, being brought in each year by overseas visitors. But as the most common viral disease spread by insects – infecting about 50 million people worldwide each year – the danger is real and growing.

Symptoms of dengue fever range from a mild to very strong fever, with severe headache, pain behind the eyes, muscle and joint pain, and a characteristic rash. In some cases it leads to dengue haemorrhagic fever, which is much more serious, with a mortality rate of about 2.5% of cases.

Because of the high rate of infection, that translates to about 12,500 deaths annually. And in parts of South East Asia, dengue haemorrhagic fever is a leading cause of hospitalisation and death among children (for more information, see the World Health Organisation’s fact sheet).

Unfortunately there is no specific treatment for dengue and no vaccine, so a lot of work is being put into controlling the mosquitoes that transmit the virus: predominantly the species Aedes aegypti.

An Aedes aegypti mosquito, the most common culprit for dengue fever, showing its distinctive white markings (Photo by James Gathany, via Wikimedia Commons)

However, in two papers recently published in Nature, researchers led by Professor Scott O’Neill, formerly of the University of Queensland and now at Monash University in Victoria, announced success in using bacteria from the genus Wolbachiato prevent these mosquitoes spreading dengue in Far North Queensland.