Wellington, July 7 (IANS): Scientists can now finally answer the question of whether you really are as old as you feel, researchers in New Zealand said on Tuesday.

A new method to determine biological aging could be a breakthrough in therapies that slow aging and help prevent age-related diseases before they occur, said researchers of the University of Otago.

The international study tracked more than 1,000 people born in the South Island city of Dunedin in 1972-1973 from birth to the present, Xinhua news agency reported.

A large number of health measures -- including blood pressure, white blood cell count, liver and kidney function -- were taken regularly along with interviews and other assessments.

The research team members from the US, Britain, Israel and New Zealand combined 18 biomarkers to determine whether people were aging faster or slower than their peers.

Otago University professor Richie Poulton said when the 18 measures were assessed together in study members at age 38, they were able to set "biological ages" for each person.

In contrast to their chronological ages, these ranged from under 30 to almost 60 years, Poulton said in a statement.

The researchers then went back to look at the individuals' same measures at age 26 and 32.

Most study members were found to be clustered around one biological year per chronological year, but others were found to be aging as fast as three biological years per actual year.

Many were staying younger than their age.

People aging more rapidly were less physically able, showed cognitive decline and brain aging, reported worse health and looked older.

The ability to detect accelerated aging at an early stage paved the way for applying therapies that slowed aging and lessen age-related ailments.

"By 2050, the world population aged 80 years and over will approach 400 million people, so we are facing an enormous global burden of disease and disability unless we can extend healthy lifespans," said Poulson.