A blood test which identifies biomarkers in blood serum may help clinicians accurately classify individuals with Alzheimer’s disease as well as identifying people who do not have the disease, researchers have revealed in an article published in Archives of Neurology.
Detecting blood biomarkers has many advantages over other ways of classifying Alzheimer’s patients, including detecting biomarkers found in the cerebrospinal fluid and neuroimaging.
As background to the article, the authors wrote:
There is clearly a need for reliable and valid diagnostic and prognostic biomarkers of Alzheimer’s disease, and in recent years, there has been an explosive increase of effort aimed at identifying such markers. It has been previously argued that, because of significant advantages, the ideal biomarkers would be gleaned from peripheral blood.
Blood is much easier to collect; it can be done at any clinic, and even at home. Most patients generally agree to a blood test. Not all facilities are able to carry out a lumbar puncture to obtain cerebrospinal fluid, the authors explain. A higher number of elderly patients will refuse to have a lumbar puncture, compared to a blood test. Some patients may not be able to undergo neuroimaging if they have a pacemaker or certain health problems.
Sid E. O’Bryant, Ph.D., Texas Tech University Health Sciences Center, Lubbock, and team in the Texas Alzheimer’s Research Consortium examined proteins in the serum of Alzheimer’s patients and 203 individuals who did not have Alzheimer’s (controls). A biomarker score was devised using statistical analyses, which included levels of the following protein biomarkers:
- fibrinogen (a clotting protein)
- interleukin-10 (associated with the immune system)
- C-reactive protein (an inflammatory marker)
The final biomarker risk score identified 80% of the Alzheimer’s patients accurately, and correctly excluded 91% of those without Alzheimer’s disease, the researchers wrote.
When age, sex, education and whether the person had the APOE gene (linked to Alzheimer’s disease) were taken into account, the score accurately identified 94% of the people with Alzheimer’s disease, and correctly classified 84% of those without Alzheimer’s.
The authors wrote:
In addition to offering more accessible, rapid and cost- and time-effective methods for assessment, biomarkers (or panels of biomarkers) also hold great potential for the identification of endophenotypes within Alzheimer’s disease populations that are associated with particular disease mechanisms.
(In the current study) a disproportionate number of inflammatory and vascular markers were weighted most heavily in the analyses.
The researchers note that their findings provide support that there is an inflammatory subtype of Alzheimer’s disease.
The scientists concluded:
The identification of blood-based biomarker profiles with good diagnostic accuracy would have a profound impact worldwide and requires further validation. Additionally, the identification of pathway-specific endophenotypes among patients with Alzheimer’s disease would likewise have implications for targeted therapeutics as well as understanding differential progression among diagnosed cases. With the rapidly evolving technology and the analytic techniques available, Alzheimer’s disease researchers now have the tools to simultaneously analyze exponentially more information from a host of modalities, which is likely going to be necessary to understand this very complex disease.
Alzheimer’s disease is a progressive neurologic disease of the brain leading to the irreversible loss of neurons and the loss of intellectual abilities, including memory and reasoning, which become severe enough to impede social or occupational functioning. Alzheimer’s disease is also known as simply Alzheimer’s, and Senile Dementia of the Alzheimer Type (SDAT) .
During the course of the disease plaques and tangles develop within the structure of the brain. This causes brain cells to die. Patients with Alzheimer’s also have a deficiency in the levels of some vital brain chemicals which are involved with the transmission of messages in the brain – neurotransmitters.
Alzheimer’s disease is the most common form of dementia. The disease gets worse as it develops – it is a progressive disease. There is no current cure for Alzheimer’s, although there are ways of slowing down its advance and helping patients with some of the symptoms. Alzheimer’s is also a terminal disease – it is incurable and causes death.
According the National Institute on Aging, there are estimated to be between 2.4 million and 4.5 million Americans who have Alzheimer’s. There are approximately 417,000 people in the UK with Alzheimer’s, according to the Alzheimer’s Society.
Click here to read about Alzheimer’s disease in more detail.
Sid E. O’Bryant, PhD; Guanghua Xiao, PhD; Robert Barber, PhD; Joan Reisch, PhD; Rachelle Doody, MD; Thomas Fairchild, PhD; Perrie Adams, PhD; Steven Waring, PhD, DVM; Ramon Diaz-Arrastia, MD, PhD; for the Texas Alzheimer’s Research Consortium
Arch Neurol. 2010;67(9):1077-1081. doi:10.1001/archneurol.2010.215
Written by Christian Nordqdvist