Backache is not just a mark of old age - about a third of teenagers suffer from it, too. A study by a Hong Kong medical school shows spinal disc degeneration also afflicts adolescents. And the condition is three times more likely if they are overweight. The findings are based on the Hong Kong Degenerative Disc Disease Cohort, launched in 2001. The largest programme of its kind in the world, it consists of more than 3,500 southern Chinese volunteers from the ages of 10 to 80. From these, researchers at the University of Hong Kong's Li Ka Shing Faculty of Medicine studied a cross-section of 83 adolescents aged 13 to 20. It found 35 per cent of them were suffering disc degeneration. And of those with damaged discs, 93 per cent suffered from lower back pain. Professor Kenneth Cheung Man-chee, of HKU's department of orthopaedics and traumatology, said: 'The effects of disc degeneration in adolescents will get worse as time goes on. In later life there will be an increased likelihood of severe pain and the need for lower back surgery.' Dr Dino Samartzis, a research assistant, added: 'Lower back pain is one of the most debilitating conditions worldwide. 'It decreases functionality and diminishes your quality of life.' Degeneration of the intervertebral discs - the joints of the spine - is one of many medical conditions, alongside diabetes and cardiovascular disease, that can result from obesity in children. 'Childhood obesity is endemic worldwide,' said Dr Robin Mellecker, a fellow at HKU's Institute of Human Performance. She said in places like Hong Kong, the mainland and India, the rise in obesity was rapid. 'This is because populations are eating and sitting more,' she said. The Department of Health says about 20 per cent of youngsters aged between six and 18 in Hong Kong were overweight or obese in 2008-09.