Screening for Alzheimer’s disease

Australian researchers have shown that a panel of blood-based biomarkers can accurately predict the presence of beta amyloid plaques in the brain, a known marker for the early detection of Alzheimer’s disease.

Alzheimer’s disease is the leading cause of dementia and is becoming a global epidemic - one quarter of a million Australians currently suffer from dementia and this is predicted to increase to one million by 2050.

The presence of extracellular beta-amyloid plaques (neocortical amyloid-beta burden or NAB) and intracellular neurofibrillary tangles in the brain are hallmark indicators that a person has Alzheimer’s disease. Amyloid-beta is a toxic protein in the brain and the clinical symptoms of the disease only present years after significant irreversible damage to the brain has occurred.

Currently, positron emission tomography is used to assess beta-amyloid plaques and identify the early onset of the disease. However, this technique is expensive and not readily available.

In this study the researchers measured the levels of biomarkers in the blood of patients with high NAB compared to those with low NAB. The levels of five biomarkers were significantly different between the two groups, and although the significance of each biomarker is not known, several are related to immune system signalling.

These results could help in the development of a non-invasive and inexpensive routine test to screen for the early detection of people at risk of developing Alzheimer’s disease. Early detection would give those at risk a much better chance of receiving treatment earlier.

Another recent study by the researchers showed that amyloid-beta levels become abnormal about 17 years before dementia symptoms appear. Thus, if the disease were detected this early it would give a much longer time to intervene to try to slow disease progression.

The researchers hope to the work will lead to the development of a population-based screening test for Alzheimer’s in the next five to 10 years.

The research is part of the Australian Imaging and Biomarkers Lifestyle Study of Aging (AIBL), a longitudinal study that involves researchers in Perth, Adelaide, Melbourne, Canberra and Brisbane. The AIBL study aims to discover which biomarkers, cognitive characteristics and health and lifestyle factors are linked with the development of Alzheimer’s disease.

The results were recently published in Molecular Psychiatry.