Twin study points to important environmental factors in Alzheimer’s disease

The question of genetic influences versus environmental influences plays a major role in research on brain aging, with researchers at the Center for Healthy Brain Aging (CHeBA) at UNSW Sydney revealing new information on one of the characteristics of the brain. 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 & Psychiatry, used a special type of imaging called amyloid PET, or “position emission tomography” to determine what proportion of the Amyloid buildup is determined by genes, and how much is determined by environmental or modifiable risk factors 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.

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 largest 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.

“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 .

Villemagne VL, Rowe CC, Sachdev PS et al. The heritability of amyloid load in the elderly: the Older Australian Twins study. The Journal of Neurology, Neurosurgery & Psychiatry, 2021. doi: 10.1136 / jnnp-2021-326677.

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