Biochemical Test Facilitates Diagnosis of Alzheimer's Disease

An innovative biochemical test has been designed that can identify a brain hormone in the blood of patients with Alzheimer's disease (AD).

A clinical study has shown that a noninvasive blood test, based on a biochemical process, may be successfully used to diagnose Alzheimer's at an early stage and differentiate it from other types of dementia.

Scientists at McGill University Health Center (MUHC; Montreal, QC, Canada) based the Alzheimer's blood test on the production of a brain hormone called dehydroepiandrosterone (DHEA). This hormone is present at high levels in the brain where it has a wide range of biological effects. A total of 86 subjects were included in this study: 19 male and 20 female AD patients; 18 male and 22 female age-matched controls; and 4 men and 3 women with mild cognitive impairment. The scientists were able to promote the production of DHEA, using a chemical process called oxidation, in blood taken from non-Alzheimer's patients. However, serum oxidation, by way of ferrous iron (Fe2+), on the blood from Alzheimer's patients did not result in an increase of DHEA.

Currently the diagnosis of Alzheimer's follows the sequence of family history, information, mental assessment and the physical exam, focusing on neurological signs. Vassilios Papadopoulos, D.Pharm., PhD, a lead author of the study, said, "There is a clear correlation between the lack of ability to produce DHEA through oxidation in the blood and the degree of cognitive impairment found in Alzheimer's disease. We demonstrated we could accurately and repetitively detect Alzheimer's disease, with small samples of blood. This test also allowed for differential diagnosis of early stages of Alzheimer's disease, suggesting this can be used as a test to diagnose the disease in its infancy."

Professor Papadopoulos believes that an accurate, easy, and specific noninvasive biochemical test that correlates with clinical findings is vital. The results of the study demonstrate that the DHEA-oxidation blood test can be used to diagnose AD at a very early stage and monitor the effect of therapies and the evolution of the disease. The study was published in April 2011, in the Journal of Alzheimer's Disease.

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