Early onset alzheimer's
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The risk of developing Alzheimer’s-associated brain plaques is only partly due to heredity, a new study of twins finds. The results suggest a role for modifiable factors as well, investigators say. 

Researchers from the University of New South Wales in Australia examined the brains of 206 identical and fraternal (nonidentical) twins using a variety of scanning methods to measured plaque presence and evidence of vascular disease. Participants also underwent clinical and neuropsychological evaluations. 

The aim was to determine whether variations in amyloid plaque accumulation may be linked to genetics, the environment or modifiable risk factors such as high blood pressure and high cholesterol. In fact, genes appear to be only partly responsible for brain amyloid burden, lead author Rebecca Koncz, Ph.D., and colleagues found.

“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,” Koncz said in a statement.

The researchers did not find a link between amyloid plaque buildup and vascular risk factors such as hypertension, diabetes, high cholesterol or a history of heart disease. They foresee larger studies to further pursue the likelihood that these contribute to Alzheimer’s risk.

Twin comparison studies offer unique insights into the genetic underpinnings of diseases and conditions because monozygotic (identical) twins share 100% of their genetic material, and dizygotic (fraternal) twins share an estimated 50% of their genes, the researchers noted. 

Full findings were published in the Journal of Neurology, Neurosurgery & Psychiatry.