Prof Alan Ferguson said more work is needed on the mental trauma caused by the Troubles

More work needs to be done calculating the mental trauma caused by the Northern Ireland conflict, an expert has said.

Results of studies so far have been inconclusive, Professor Alan Ferguson, chief executive at the Northern Ireland Association for Mental Health, added.

He was giving evidence to a joint session of the health and education committees at Stormont. Around one in five people show signs of possible mental health problems, according to the Government's central statistics body.

"There have been a number of attempts to look at psychological well-being in Northern Ireland as a consequence of the troubles but the results have been pretty contradictory," he said.

"I find that very surprising. To me there has to be very clear evidence around that."

He added that how the research was carried out may be to blame. In 2006 the Health Promotion Agency (HPA) found conflicting views to mental health. Two thirds of those asked underestimated the proportion of people who might have a mental health problem at some point.

Parts of north and west Belfast have high youth suicide rates, but there is also a lot of deprivation and problems may not be directly connected to the 30-year conflict.

Ulster Unionist Assembly member Basil McCrea quizzed Professor Ferguson. The MLA said Northern Ireland had a high rate of Disability Living Allowance claims (around 2,000 fresh applications a month in 2007) and alleged this was largely due to mental health.

"It comes from the traumatic events that we have had in the past, particularly in some of the more deprived areas," he said.

"I am just wondering if the connection has been made about how serious our mental health issues are, that they are systemic, endemic in fact in our society and we have to start dealing with them?"