LONDON (Reuters) Almost half of all adults worldwide suffer from headache disorders such as migraines and tension headaches and the problem has huge economic and societal costs, the World Health Organisation said this week.Yet headaches are widely under-recognised, under-diagnosed and under-treated, and the scant knowledge about them and the burdens they impose must be improved, the WHO said.Publishing its first global atlas on headaches, the Geneva-based United Nations health body said it found that 47 percent of all adults have a headache disorder and “the financial costs to society through lost productivity are enormous”.In the European Union (EU) alone, 190 million days are lost from work every year because of migraine, it said.“Headache and migraine disorders are greatly underrated and underreported by health systems and receive too little attention,” Dr Shekhar Saxena, the WHO’s director of mental health and substance abuse disorders, said in an emailed statement about the report.Migraine affects around one in six women and one in 12 men, and has been estimated to be the most expensive brain disorder to society in the EU and the United States. The WHO report found that most importantly, headache disorders are very disabling: Worldwide, migraine alone is the cause of 1.3 percent of all disability due to illness, it said, and experts estimate that taken together, all headache disorders account for double this burden. Migraine alone is the cause of an estimated 400,000 lost days from work or school every year per million of the population in developed countries.