(CBS/AP) Is mental illness more common in Europe than in other parts of the world? Reliable statistics aren't readily available, but mental health experts expressed surprise over new research showing that 38 percent of the European population, or 165 million people, have a mental or neurological disorder.
"Although the figure seems shockingly high, this is the most rigorous study done in Europe," said Graham Thornicroft, a professor of community psychiatry at the Institute of Psychiatry at King's College London, who was not linked to the study. "The real tragedy is that so few people with mental health problems receive treatment."
Experts estimate that only one-third of people affected by the disorders get help.
Researchers arrived at the eye-popping figure after reviewing data from previous studies involving more than 500 million people in 27 European countries, plus Switzerland, Iceland, and Norway. They considered more than 90 mental and neurological problems, including attention-deficit hyperactivity disorder and other problems that are more common in children as well as those typically found in the elderly, such as dementia.
The rates of mental and neurological disorders didn't appear to be rising, compared to a similar study in 2005. The most common problems include anxiety disorders, insomnia, depression, alcohol and drug dependence and dementia.
"Not all of these people require psychiatric interventions," said Matt Muijen, a mental health expert with World Health Organization's European office in Copenhagen. "The 38 percent is indicative of stress in society, not necessarily psychiatric disorders."
Because researchers in other areas use varying definitions of what constitutes mental illness, it's hard to compare European rates to those elsewhere, he said. The NIH estimates that about 26 percent of American adults have some type of mental disorder.
Other experts said the numbers of people with mental health problems appeared higher than what is commonly believed because most patients don't report their illness and because this study includes disorders in children and the elderly.
Study author Hans-Ulrich Wittchen said many patients still face discrimination and limited services when seeking treatment, adding, "Mental health disorders are Europe's largest health care challenge in the 21st century."
The study was published in European Neuropsychopharmacology and presented at a meeting in Paris on Tuesday.