What the scientists are saying...

Do you feel you're ageing faster than those around you?

Getting older, faster

Do you feel you're ageing faster than those around you? The truth may be that you are, but there's precious little you can do about it, since it's hard-wired into your DNA, says Scientific American. Doctors have long distinguished between people's chronological age, which is how old they are in years, and their biological age, which is based on the condition of their cells. Now, scientists have isolated a particular genetic variant which determines whether or not a person will age quickly. So in future, young people could be tested to see whether they carry the variant, and should therefore alter their lifestyles accordingly. For a study published in the journal Nature Genetics, British researchers Nilesh Samani and Tim Spector analysed blood samples from 3,000 volunteers: they found that the 38% who possessed the variant had a biological age four years older, on average, than people of the same chronological age who did not carry it. (The unfortunate 7% who had two copies of the malign variant were as much as eight years older, biologically.) The researchers measured biological age by the length of people's telomeres - protective strands of DNA that shorten over time, gradually losing their ability to guard cells against deterioration.

Autism risk increases with age

Women who delay having children may be increasing their risk of having a child with autism. A study of all births that occurred in California in the 1990s suggests that the risk increases by 18% for every five-year increase in maternal age - and that by the time a woman is 40, she is 50% more likely to have an autistic child than a woman in her late twenties, and 7% more likely than a woman under 25. The study, which involved 12,000 children with autism, and a control group of around five million, showed that paternal age is also a factor, though a more complicated one: a man in his forties does have an increased risk of having an autistic child - but only if his partner is under 30. If his partner is over 30, the additional risk dissipates.

Third-hand smoke

It's not enough just to keep your children away from people who are smoking. New research has added to fears that smokers can remain a danger to children, even after they have put out their cigarettes and left the room. Scientists at the Lawrence Berkeley National Laboratory in the US have found that nicotine residue clings to clothing, furniture and even floors, where it can react with a common gas (nitrous oxide) to form carcinogenic compounds known as TSNAs. The researchers stress that more research into "third-hand smoke" is needed, but warn that, in theory, infants could be at risk as they crawl around in rooms where people have smoked, and come into contact with dust on rugs and in carpets.

Are you wasting time in the gym?

Some people can go to the gym as often as they like, but it won't do much for their health. According to new research, around 20% of us carry genes that make it difficult for our muscles to absorb oxygen - and therefore render aerobic exercise all but useless, as far as warding off heart disease and other ailments is concerned. For the study, conducted at the University of London, scientists subjected 500 volunteers to a five-month-long programme of aerobic exercise. By the end, most showed some significant improvement in their V02 max - a measure of the ability of oxygen to get to the muscles where it is needed. But one in five showed no such improvement, because their DNA prevented it. Those people should forget jogging, and aim to keep their hearts healthy by other "lifestyle*' changes, such as eating a healthy, balanced diet.