Researchers are baffled why fit teenagers can also fall victim to the 'elderly people's disease' Despite several studies over the past decade, doctors remain mystified as to why some healthy people as young as 18 suddenly succumb to a stroke, a member of the Hong Kong Stroke Society says. Queen Mary Hospital alone has treated eight stroke victims aged 18 to 25 in the past 10 years. None had any hereditary or hidden diseases, such as meningitis, deformity of blood vessels or prenatal heart diseases, which could trigger the condition. 'We still monitor the situation of those young patients who come back to our clinic regularly for rehabilitation and regular check-ups,' said Raymond Cheung Tak-fai, associate professor of medicine at the University of Hong Kong, which is associated with the Queen Mary Hospital. 'It remains a great mystery to us why they were suddenly hit by strokes.' Dr Cheung, also president of the Hong Kong Neurological Society and honorary secretary of the Hong Kong Stroke Society, said all eight young patients had survived and most had regained a healthy, normal life. Some, however, had developed severe permanent disabilities, including one young man who is now wheelchair-bound. Dr Cheung said the median age of stroke patients was 70. About 3 per cent of stroke patients at Queen Mary Hospital are under 45, and just 1.5 per cent are between 18 and 30. The hospital treats about 1,200 stroke patients a year. In an attempt to increase understanding of the condition on World Stroke Awareness Day today, Dr Cheung warns that drug abuse increased the risk, with drugs such as cocaine and amphetamines raising blood pressure and causing blood vessels to burst. However, the eight young patients treated by the hospital had insisted they did not take drugs. Dr Cheung said that both the incidence of and death rates from strokes had remained stable in Hong Kong over the past few years. But he said the condition remained a major health problem due to Hong Kong's ageing population. Dr Cheung quoted Hospital Authority figures that showed about 25,000 stroke-related visits were made to the city's public hospitals each year, with about 3,500 deaths annually resulting directly from the disease. But Dr Cheung believes the death rate could be even higher, since strokes trigger many other life-threatening diseases, such as pneumonia. 'Some patients develop pneumonia because they have become bed-ridden after a stroke. Even though we may classify pneumonia as the cause of death on their death certificate, it was in fact brought on by a stroke.' Dr Cheung said 60 per cent of strokes could be prevented by maintaining a healthy lifestyle, controlling blood pressure, cholesterol and diabetes, and avoiding smoking and alcohol. 'Of course, the other 40 per cent are out of our control, such as hereditary diseases and ageing.' According to the International Stroke Society, strokes are a major global health threat, affecting 15 million people worldwide each year. One-third of sufferers die and another third are left permanently disabled.