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Too much alcohol dulls your senses, but a study in Japan shows that moderate drinkers have a higher IQ than teetotalers. Researchers at the National Institute for Longevity Sciences in Aichi Prefecture, 250 kilometers west of Tokyo, tested the IQs of 2000 people between the ages of 40 and 79. They found that, on average, men who drank moderately—defined as less than 540 milliliters of sake or wine a day—had an IQ that was 3.3 points higher that men who did not drink at all. Women drinkers scored 2.5 points higher than female teetotalers. The type of alcohol didn't influence the results. The volunteers tried a variety of tipples, which ranged from beer and whisky to wine and sake. The researchers are quick to point out that the results do not necessarily show that drinking will make you more intelligent. 'It's very difficult to show a cause-effect relationship,' says senior researcher Hiroshi Shimokata. 'We screened subjects for factors such as income and education, but there may be other factors such as lifestyle and nutritional intake.' Shimokata says that people who drink sake, or Japanese rice wine, tend to eat more raw fish. This could be a factor in enhanced intelligence, as fish often contain essential fatty acids that have been linked to brain development. Similarly, wine drinkers eat a lot of cheese, which is not something Japanese people normally consume or buy. Shimokata says the high fat content of cheese is thought to be good for the brain. If alcoholic drinks are directly influencing IQ, Shimokata believes chemicals such as polyphenols could be the critical factor. They are known to have antioxidant properties and other beneficial effects on ageing bodies, such as dilating constricted coronary arteries. The study is part of a wider research project to find out why brain function deteriorates with age.