What the scientists are saying…

Is back pain killing us? Lower back pain – believed to be the world’s leading cause of disability – may be an indicator of early death, a study has suggested. Researchers at Sydney University examined health data on 4,390 elderly Danish twins, and found that those who suffered from back pain were significantly more likely to die in any year than those without it. “Our study found that compared to those without [it], a person with spinal pain has a 13% higher chance of dying every year,” said team leader Dr Paulo Ferreira. “This is a significant finding as many people think that back pain is not life-threatening.” He does not think there is a direct causal link between back pain and premature death; rather that in some patients, living with pain precipitates a decline in overall health. “It’s a whole cascade of events,” he said. People with back pain “get more depressed, don’t socialise as much, don’t walk as much – these are all factors associated with mortality”. What the study shows, he added, is how vital it is that people with back pain remain active: as well as being a useful treatment for back pain, exercise helps people stay healthy.

Clever teens and cannabis Clever adolescents are less likely than their peers to smoke cigarettes during their teenage years – but more likely to drink alcohol and use cannabis, scientists have found. For the University College London study, 6,059 young people across England were ranked in three categories for intelligence, according to their performances in national tests at age 11. The researchers went on to track their levels of selfreported substance abuse in early (13-17), and then late (18-20), adolescence. While the brightest youths were the least likely to smoke at any point, they were – by late adolescence – more than twice as likely as those in the lowest group to drink “regularly and persistently”, and almost twice as likely to use cannabis. The researchers suspect the explanation for the varying smoking rates is simply that middle-class parents (whose children tend to perform better in academic tests) are more likely to warn their children about the dangers of smoking. However, when it comes to alcohol and cannabis, the researchers speculate that IQ level itself is a factor: they suggest that bright adolescents are more curious, and therefore more likely to experiment with drugs.

Why elephants rarely snooze Elephants are said never to forget. Now it seems they also rarely sleep: they need just two hours a night, on average, according to a small study – less than any other mammal. And when on the move, they can go 48 hours without shut-eye (without compensating later with more sleep). In captivity, where they are under no pressure to find food or escape predators, elephants will sleep for up to seven hours a day. To test their sleep patterns in the wild, researchers fitted monitoring devices to the trunks of two females in Chobe National Park, Botswana, and tracked them for 35 days. If the animals’ trunks (the most active part of their body) were still for five minutes, they were presumed to be asleep, reports the New Scientist; they were also fitted with gyroscopes, to determine their sleep position. The pair were found to sleep in four or five short bursts, for a total of two hours a night; and they only lay down to sleep every three or four days – suggesting they don’t often go into REM (rapid eye movement) sleep – a dreaming sleep, at least in humans. Most mammals are thought to go into REM sleep daily. Smaller mammals tend to get more sleep than larger ones; even so, that elephants can survive on so little came as a surprise.

Obesity linked to 11 cancers Overweight people appear to be more susceptible to a range of cancers. A team analysed the results of 204 earlier reviews of studies looking at the link between body fat and 36 different cancers, and found “strong evidence” that 11 types of cancers are tied to obesity. The cancers, many of which are digestive or hormonal, include breast cancer and cancers of the kidney, bowel and colon. Though the study doesn’t prove excess fat leads to cancer, the team believe the relationship is causal. “We know that if you are overweight, it causes lots of disruption of hormonal and metabolic pathways,” Dr Marc Gunter, of the International Agency for Research on Cancer, told The Guardian.