Research may offer new possibilities for early diagnosis, preventive treatment of dementia

Reviewed by Emily Henderson, B.Sc.November 23, 2020

Researchers from the Karolinska Institutet in Sweden studied the incidence and regional distribution of Alzheimer’s disease biomarkers in the brains of people with Down syndrome.

The findings may offer new possibilities for early diagnosis and preventive treatment of dementia. The study is published in Molecular neurodegeneration.

While medical advances and improved quality of life have increased the life expectancy of people with Down syndrome to an average of 60 years, up to 90% develop Alzheimer’s disease if they live long enough.

In Alzheimer’s disease, clumps of amyloid from the plaques around neurons in the brain, while another protein, tau, accumulates within nerve cells in what are called tangles. Plaque and tangles first appear in one region of the brain and then spread, causing a gradual deterioration of functional damage.

People with Down syndrome have an extra copy of chromosome 21. One of the reasons for the high incidence of Alzheimer’s disease in people with Down syndrome is that the gene that codes for amyloid production is located on chromosome 21, which it can cause amyloid to build up in the brain as early as childhood.

“Previous studies of Down syndrome by our group and others have been able to show that pathological forms of amyloid and tau can appear years before someone shows signs of dementia,” says Lotta Granholm, professor at Karolinska Institutet and all. University of Denver, and one of the lead authors of the article.

In this study, the researchers investigated the extent and distribution of tau and amyloid in the brain tissue of people with Down syndrome with or without a diagnosis of Alzheimer’s and people who had died with Alzheimer’s disease but without others. functional disabilities.

Their analyzes showed that the incidence of tau in the brain tissue of people with Down syndrome and Alzheimer’s disease was higher than in people with Alzheimer’s but without Down syndrome, suggesting that tau is an early change in Down syndrome.

“In addition to a high level of tau, we also measured a different regional distribution of tau in the brains of people with Down syndrome and Alzheimer’s disease compared to the control group,” says Laetitia Lemoine, assistant professor in the Department of Neurobiology, Care Sciences and Society, Karolinska Institutet.

Traces of tau have also been detected in the brain tissue of fetuses with Down syndrome. According to the researchers, early prophylactic measures against tau accumulation could prevent the development of Alzheimer’s disease in childhood for this group of patients.

Our studies support the need to continue research on the progress and incidence of amyloid plaque and tau in the brain by imaging the brains of living individuals with Down syndrome. “

Agneta Nordberg, second lead author and professor, department of neurobiology, nursing sciences and society

“Our goal is a better understanding of how we can take the first steps to discover pathological changes that produce cognitive symptoms and initiate drugs that help improve quality of life.”