Two people are suffering from the same chronic illness. However, one has a positive outlook on the situation, while the other thinks it is the "end of the world".

Associate Professor Chua Hong Choon, chief executive officer of the Institute of Mental Health (IMH), noted that their different perspectives do not arise from the illness and have nothing to do with its associated symptoms.

"We are trying to understand this phenomenon... what gives people wellness on top of their illness," he said at a media briefing yesterday.

A team of five researchers, led by Associate Professor Rob van Dam, domain leader of epidemiology at the National University of Singapore's Saw Swee Hock School of Public Health, is hoping to uncover the underlying factors in a four-year- long Singapore Wellness Study.

Professor Chia Kee Seng, dean of the school, said: "We want to find out the factors that improve wellness, and increase and promote them."

The study, involving some 10,000 participants from the multi-ethnic cohort of the school's Singapore Population Health Studies, will be conducted through a questionnaire, interviews and physical examinations.

Some of the survey questions include "How confident are you that you can overcome obstacles?" and "During the last two weeks, how often did you feel content?".

When the survey is completed by 2021, the team hopes to present its findings to the Government to inform public health policies and improve wellness here.

Co-investigator Mythily Subramaniam, director of the research division at IMH, said: "A systematic and detailed study of the wellness of the local population can help provide insights to address key problems and proactively initiate preventive measures."

Over the past three years, there have been at least three national studies on mental health, including the Singapore Mental Health Study, the Well-being of the Singapore Elderly Study, and the Mind Matters Study.