A new national brain research project is being launched in Dunedin, to unlock the secrets of the ageing brain.

University of Otago staff are involved in the study, which also includes researchers based in Auckland.

The project's funded through the government.

Otago University became the co-host to the national brain centre of research excellence last year.

It's hoped this project will lead to better understanding about how New Zealanders can enjoy improved brain health in old age.

By the year 2036 it's expected that a fifth of the population will be over the age of 65.

Old-age related issues cost the country billions each year.