Clean air prolongs life Cleaner air increased life expectancies in 51 US cities by a 'remarkable' five months, on average, and by double that in what were the worst polluted areas, say researchers from Brigham Young and Harvard universities, based on an analysis of data over two decades. By 2000, Americans were living 2.72 years longer, on average, than 20 years earlier, with as much as five months of that gain due to reduced pollution, AP reports. 'Such a significant increase ... is remarkable,' says team leader Arden Pope. One in five teens develop 'iPod ear' As many as one in five teenagers aged 16 to 20 has hearing problems usually associated with old age, and German specialists blame MP3 players for much of the damage. The maximum volume for such devices under European Union rules is 100 decibels, but the German association of ear, nose and throat specialists says this is too high. Workplace safety rules require ear protectors when noise levels are above 85 decibels, AFP reports. Alzheimer's less for social types Elderly people who are calm and enjoy socialising may be as much as 50 per cent less likely to develop dementia such as Alzheimer's than those who are stressed and more isolated, say researchers from Sweden's Karolinska Institute, based on a six-year study of more than 500 adults. They were aged in their early 80s on average at the start of the study and more than 140 were diagnosed with dementia by the end, WebMD reports. The combination of being calm and outgoing appears to be more significant than either trait alone, says team leader Hui-Xin Wang. Vitamin D and dementia linked The so-called sunshine drug, vitamin D, may help stave off dementia, say British and US researchers, based on analysis of the health records of more than 2,000 people aged 65 and over. They found as levels of vitamin D decline, levels of cognitive impairment rise. Those with the lowest vitamin D levels were more than twice as likely to have some form of dementia as those with the highest levels. Sunshine is a key source of vitamin D, BBC online reports. Coffee may perk up the brain Meanwhile, Scandinavian researchers say that drinking moderate amounts of coffee in middle age may also help reduce the risk of dementia in later life, based on analysis of the records of more than 1,400 people over 21 years. Those who drank three to five cups a day were significantly less likely to develop dementia, says the team from Finland's University of Kuopio and the Karolinska Institute. Previous studies have shown links between caffeine and reduced risks of Parkinson's and type 2 diabetes, WebMD reports. The researchers say this may have something to do with antioxidants in coffee. Live-in mates aid fertility When male mice live with females, their reproductive cycle lasts up to 20 per cent longer, say University of Pennsylvania researchers. It's not known if this occurs in humans, but the team says the findings have 'significant implications' for managing livestock and animal numbers in the wild. The decline in fertility appears to be due to cellular deterioration in the sperm-production process, although the researchers aren't sure why, livescience.com reports.