Knowing about abnormally configured proteins called amyloid plaques that gather in the spaces between nerve cells and how they come to aggregate there, probably isn't everyone's cup of tea.

Thankfully though, researchers from the University of NSW's Centre for Healthy Brain Ageing were intent on determining what proportion of amyloid accumulation is genetic and what is environmental.

To do so, they looked into the brains of twins, both identical and non, and came away with a revealing insight into one of the key telltale signs of Alzheimer's disease.

The world first study found modifiable risk factors play a stronger role in the condition than first thought.

Led by Dr Rebecca Koncz, the research employed a special type of imaging called amyloid PET or positron emission tomography to precisely measure metabolic activity.

Amyloid is something which accumulates in the brain very early in the development of Alzheimer's, she says.

"It is a hallmark feature of the condition that starts to accumulate decades before memory problems become apparent."

According to CHeBA co-director and leader of the Older Australian Twins Study, Professor Perminder Sachdev, the twins comparison provided a unique opportunity to investigate the nature versus nurture conundrum.

The wonder of monozygotic twins (those from a single egg) is that they share 100 per cent of their genetic material -while dizygotic twins (from two eggs) share an estimated 50 per cent.

Meanwhile, Australia happens to have one of the world's leading twin registries - Twin Research Australia - members of which participated in the study.

Dr Koncz and her colleagues discovered the heritability of amyloid is moderate - meaning genes play a lesser role in determining the variation in amyloid build-up.

"This is significant because it tells us that whilst genes are important, there is actually a major environmental contribution that may respond well to intervention," she said.

By way of qualification, however, the study did not find a specific association between vascular risk factors like hypertension, diabetes, high cholesterol or a history of heart disease and amyloid burden.

To shed more light on this aspect of the research, larger studies may be needed.

Even so, Prof Sachdev said: "Identifying modifiable risk factors will lead us to interventions that reduce the risk of amyloid accumulation and ultimately risk reduction of developing Alzheimer's disease."

The Older Australian Twins Study is a longitudinal project investigating brain ageing in older twins over the age of 65.

Dr Koncz's findings have been published in The Journal of Neurology, Neurosurgery and Psychiatry.