Australia's 18 and Up study to follow 100,000 people across their lives

The Sax Institute, an independent not-for-profit research institute, launched the 18 and Up study on Thursday, with plans to recruit 100,000 Australians aged 18 to 45 and follow their health throughout their lives. It is described as the country's largest intergenerational study of wellbeing and ageing.

The project builds on 45 and Up, which the institute began two decades ago and which is now the largest population-based cohort study in the southern hemisphere, with more than 267,000 participants aged 45 to over 100. Those participants have been repeatedly surveyed and their answers linked to other datasets, producing findings on smoking, dementia prevention and differences in cardiovascular outcomes between men and women.

A gap in long-term data

Adjunct Prof Justine Gatt, the scientific director of 18 and Up, said long-term data on younger generations is lacking, because existing studies often capture only a snapshot in time.

"Almost two in five young Australians aged 16 to 24 experienced a mental disorder in the past year, and that number has been rising," said Gatt, a neuroscientist and mental health researcher. "Yet we still lack the long-term evidence needed to understand why."

Suicide is the leading cause of death among Australians aged 15 to 44. Researchers say there is an urgent need to understand the factors driving poor mental health in order to improve prevention and treatment.

Children and grandchildren of 45 and Up participants will be invited to take part. Gatt said this would help researchers understand how health is shaped by a mix of family history, lived experience and social conditions, and how those factors interact across generations.

Cancer questions included

Dr Martin McNamara, chief executive of the Sax Institute, said cancer would also be an important part of the first round of surveys. Since 2000, early-onset cancers – those diagnosed after adolescence but before the age of 50 – have increased in Australia and elsewhere, including bowel, thyroid and breast cancers. Scientists believe increased screening, changing lifestyles and different early-life exposures to risk factors may all play a part, and there have been calls for urgent research.

Participants will be asked about their health, lifestyle, social circumstances and background. With consent, that information will be linked to other records such as cancer registries and Medicare. McNamara said following people over time would help identify ways to fix and reorganise health and care systems.

The study will adapt as participants age, receiving age-relevant questions, and will factor in emerging health conditions or pandemics. It is funded by a $4.5m National Health and Medical Research Council grant, with recruitment beginning in November.

Prof Emily Banks, an epidemiology and public health professor at the Australian National University and a former scientific director at the Sax Institute, said large cohort studies give researchers a window into a population. Data from 45 and Up, which she used in 2025 to show that smoking-related illnesses kill 66 Australians a day, has been used by more than 800 researchers worldwide.

Source: The Guardian World.