The question of genetic vs environmental influences plays a major role in research on brain aging, with researchers from UNSW Sydney Center for Healthy Brain Aging (CHeBA) revealing new knowledge about one hallmark of Alzheimer’s disease – amyloid plaques – by examining the brains of identical and non-identical twins.
The first global study, led by Dr Rebecca Koncz and published in The Journal of Neurology, Neurosurgery and Psychiatry, used a special type of imaging called amyloid PET, or “position emission tomography,” to determine what proportion of amyloid buildup is determined by genes and what proportion is determined by environmental risk factors or modifiable such as high blood pressure and high cholesterol.
“Amyloid is a protein that accumulates in the brain very early in the development of Alzheimer’s disease,” said Dr. Koncz.
It is a hallmark of the disease that begins to accumulate decades before memory problems become apparent.
According to Professor Perminder Sachdev, Co-Director of CHeBA and Leader of the Older Australian Twins Study, twins provide a unique opportunity to study the relative importance of genetic and lifestyle factors for Alzheimer’s disease, as the Monozygotic twins share 100% of their genetic material, and dizygotic twins share about 50%. Australia has one of the world’s leading registries of twins – Twin Research Australia – whose members participated in the study. Amyloid PET imaging was performed in collaboration with the Department of Molecular Imaging and Therapy, Austin Hospital, Melbourne, and the Department of Nuclear Medicine and PET, Prince of Wales Hospital, Sydney.
The researchers found that the heritability of amyloid is moderate, which means that genes play only a moderate role in determining the variation of amyloid accumulation in the brain.
This is important, because it tells us that while genes are important, there is actually a major environmental contribution that may respond well to an intervention. Dr Rebecca Koncz
“Regarding modifiable risk factors, we examined whether vascular risk factors such as hypertension, diabetes, high cholesterol or a history of heart disease were significantly associated with the amyloid burden or had a genetic basis. common, “said Dr. Koncz.
Although the study did not find an association between vascular risk factors and amyloid, larger studies are needed.
“Identifying modifiable risk factors will lead us to interventions that will reduce the risk of amyloid buildup and ultimately a reduction in the risk of developing Alzheimer’s disease,” said Prof. Perminder Sachdev .
CHeBA’s Older Australian Twins study is a longitudinal study of healthy brain aging in twins over 65 years of age. Healthy aging is characterized by low levels of disability, high cognitive and functional capacity, and active engagement in life. The most important ingredient in healthy aging is a healthy brain, free from age-related diseases and dysfunctions.
CHeBA Authors: Dr Rebecca Koncz, Dr Anbupalam Thalamuthu, Associate Professor Wei Wen, Dr Vibeke Catts, Dr Teresa Lee, Dr Karen Mather, Dr Jiyang Jiang, Professor Julian Trollor, Professor, Perminder Sachdev
COLLABORATING AUTHORS – Vincent Dore, Melissa J. Slavin, Eva A. Wegner, David Ames, Victor L. Villemagne, Christopher C. Rowe