A 15-year study investigating the relative contributions of genetic and environmental factors on the brain health of twins has taken advantage of technology to reach twins residing outside of metropolitan areas.

The move to an online platform will not only enable the inclusion of one-third of Australian twins living outside major cities but will also facilitate the study of differences in access to specialist health care, health seeking behaviour and other potential contributors to the shortened lifespan of people living in regional and rural areas.

The Older Australian Twins Study, a major collaborative study led by UNSW Sydney’s Centre for Healthy Brain Ageing (CHeBA), has contributed important research findings in the world’s quest for answers to the question of ‘genetics vs environment’.

Commencing in 2007 to investigate genetic and environmental differences and how they relate to either healthy brain ageing or age-related neurocognitive disorders, the study takes advantage of the fact that identical twins share 100 per cent of their genetic code, whereas non-identical twins share only approximately 50 per cent.  This means that twin studies provide a unique opportunity to identify which specific factors contribute, and which contribute the most, to health outcomes in older age.

The study measures many behavioural and environmental factors, in particular lifetime physical and mental activity, physical and psychological trauma, losses and life events, early-life socio-economic environment, alcohol and drug use, occupational exposure and nutrition.  There is a wealth of genetic data.

Many features of the Older Australian Twins Study distinguish it from other investigations, including its longitudinal design, comprehensive neuropsychological assessments, brain imaging measures, its range of genetic data, and links with a brain donor program.

The twin study design is the best method for providing the strongest possible evidence for cause of disease from an observational study.

According to Professor Perminder Sachdev, Co-Director of CHeBA and Project Leader of the Older Australian Twins Study, “the depth and breadth of data collected in combination with the very large twin sample envisaged as part of taking the study online makes it unique in Australia and internationally.”

“Given we know the deposition of a marker of Alzheimer’s pathology in people without dementia is only moderately determined by genetics, it suggests there may be many modifiable risk factors for this common type of dementia,” said Professor Sachdev.

Since studies by the Australian Institute of Health and Welfare have shown that regional and remote populations are less likely to have convenient access to a General Practitioner, they are also much less likely to have local access to medical specialists. In contrast, populations in outer regional and remote areas have a higher rate of hospital admissions.

Do you think genetics or the environment play a bigger role in brain health?