Fifteen-year-old males who ate fish at least once a week displayed higher cognitive skills at the age of 18 than those who ate it less frequently, according to a Swedish study of nearly 4,000 teenagers published in the March issue of Acta Paediatrica. Eating fish once a week was enough to increase combined, verbal and visuospatial intelligence scores by an average of 6%, while eating fish more than once a week increased them by just under 11%. Researchers compared the responses of 3,972 males who took part in the survey with the cognitive scores recorded in their Swedish Military Conscription records three years later.