A significant proportion of Lebanese people have experienced at least one mental disorder at some point in their lives, according to a new study, with war exposure increasing the likelihood of onset.

The study assessed the prevalence of mental disorders in Lebanon, conducting face-to-face interviews with a representative sample of 2,857 adults, in a paper published in PLoS Medicine this month.

The researchers say this is the first nationally representative general population survey of mental disorders in the Arab world.

They found that 25 per cent of the sample had experienced a mental health disorder. Anxiety and mood disorders were the most common disorders found, affecting 16.7 per cent and 12.6 per cent respectively, with women at higher risk. Major depression was noted in 9.9 per cent of patients.

A low number of people sought treatment in the first year of their disorder, with an average delay of six years since onset - despite Lebanon having one of the highest ratios of healthcare professionals per person in the Arab world.

The researchers suggest that the stigma attached to mental disorders, and a lack of general awareness, may be the reason.

They also found that almost half of patients had been in a war zone - as a civilian, rescue worker or refugee. Those exposed to trauma between the ages of 0-10 years had an increased risk of developing a disorder for the first time.

"This age group might have a higher risk to develop post-traumatic disorders," says Elie Karam, from the Department of Psychiatry and Clinical Psychology at Saint George Hospital in Beirut and lead author of the study. "If true it might allow us to identify candidates before disorders show up."

Karam said there is a need to educate people on mental disorders to improve understanding and recognition of their presence, which will eventually lead them to seek treatment.

However, Chawki Azouri, a psychologist and researcher at Saint-Joseph University in Beirut, is sceptical of the results. Azouri, a founder of 'Sahatouna Lana', a Lebanese nongovernmental organization monitoring health policies, says the methodology used in the study is controversial, producing exaggerated numbers of disorders that only benefit pharmaceutical companies marketing new drugs.

"No national health policies should be designed according to this study alone," he says.