Alzheimer’s: Blood tests show promise in identifying disease earlier

In one study, researchers in China analyzed a database of 1,160 blood proteins to find markers that may help with early identification as well as determining the stage of Alzheimer’s disease.

The scientists used blood samples from 180 people of Chinese descent in Hong Kong over the age of 60. The participants consisted of 106 people with clinically diagnosed Alzheimer’s as well as 74 healthy controls.

The researchers chose 18 proteins that can signal changes associated with mild cognitive impairment and Alzheimer’s disease. They found that this protein panel was accurate for classifying mild cognitive impairment and Alzheimer’s across two different cohorts.

The researchers found that the changes detected by their test lined up well with Alzheimer’s disease progression. They said their panel could identify Alzheimer’s in its early stages, provide information on a person’s current stage, and allow medical professionals to determine the progression of the disease.

The researchers noted that these biomarkers were the same across ethnic groups, specifically Chinese and European.

“Our data showed that the identified blood biomarkers have significant alteration in individuals with mild cognitive impairment (MCI),” said Yuanbing Jiang, PhD, the lead author of the study and a postdoctoral fellow at the Hong Kong University of Science and Technology. “Since these MCI individuals typically have no obvious symptoms at the current stage and have around 5 to 10 years to develop Alzheimer’s (i.e., the onset of dementia symptoms), we believe that these identified blood biomarkers start to have dysregulations at least 5 to 10 years prior to the onset of symptoms.”

“It is our vision that this assay could be added as a routine blood test in the future for screening older adults with risks of developing Alzheimer’s,” Yuanbing told Medical News Today. “We will continue working on the validations and optimizations of this assay to facilitate its applications in future clinical settings. It will be recommended for people at age> 50 since the onset of AD symptoms is typically at 65 years old while the disease starts to develop (e.g., pathology occurs in the brain) after 50 years old.”

Researchers noted that one limitation of their study is the small sample size.

In the second study presented at the conference, researchers in Hong Kong reported that they developed a panel of 21 blood proteins that can help identify biological changes related to Alzheimer’s disease.

“Current [Alzheimer’s] diagnosis will utilize brain imaging of disease hallmark, Aβ or biomarker measurement from CSF [cerebrospinal fluid],” Li Ouyang, a lead author of the study and a scientist at the Hong Kong University of Science and Technology, told Medical News Today. “These methods are either expensive or invasive. Our multiplex biomarker assay can accurately detect [Alzheimer’s] through a simple blood draw, which provides a cheaper and easier way or even large-scale screening for [Alzheimer’s] detection in the clinical setting. It could also be applied as a monitoring tool for disease progression and drug response evaluation.”

The scientists said they built on their previous profiling of blood proteins used to identify and diagnose Alzheimer’s. They used this information to identify 21 proteins that could classify Alzheimer’s and mild cognitive impairment for the purpose of monitoring cognitive decline and the development of tau proteins.

The researchers said that this panel outperformed other blood biomarker panels and achieves earlier Alzheimer’s identification from cognitively normal populations. It can also provide information on the status of biological processes. They reported that the accuracy rate for Alzheimer’s detection was between 94% and 98%. For those with mild cognitive impairment, it was between 84% and 89%.

“Normally, [Alzheimer’s] patients are diagnosed when they develop obvious symptoms,” said Li. “Additionally, patients with MCI will take 5 to 10 years to develop [Alzheimer’s].”

“In our study, we have recruited human subjects, including cognitively normal, mild cognitive impairment, and [Alzheimer’s] patients,” Li added. “The results of our biomarker assay showed that we can discriminate the MCI and [Alzheimer’s] samples from [clinically normal] individuals. This indicates we can identify the MCI subjects at least 5 to 10 years before symptoms manifest using our multiplex biomarker assay.”

The third study released at the conference reported that men with Alzheimer’s experience faster cognitive decline compared to women with the disease.

The researchers used brain scans and blood samples from 76 older adults participating in the Baltimore Longitudinal Study of Aging.

The researchers reported that men showed quicker increases in:

Women and men have a relatively similar incident rate for Alzheimer’s until age 80, when women are significantly more likely to develop dementia, according to a study published in 2018. The researchers of the current study noted that this is, at least in part, due to women’s greater average longevity.

They also noted that one limitation of their study is the small sample size.

Early detection of Alzheimer’s is important because treatment is more effective when it is started early in the disease process.

It can also help the patient, family members, and caregivers be better prepared for symptoms as they appear. According to the Alzheimer’s Society, ways early detection can help also include:

• Being actively involved in healthcare and other personal care decisions
• Setting priorities and pursuing what is important
• Expressing thoughts in terms of care, presently and later in the disease
• Preparing for the futures financially
• Deciding on living arrangements, including care facilities

“Alzheimer’ disease is caused by abnormal proteins called beta amyloid. All humans make this protein but only in some people does it stick to itself and form plaques. The amyloid plaques deposit throughout the brain and lead to brain cells dying. It is the death of the brain cells that cause memory loss and the progressive decline of Alzheimer’s disease,” said Dr. David Hunter, an assistant professor of neurology with the McGovern Medical School at UTHealth Houston who was not involved in the studies. “However, we now know the amyloid plaques first accumulate 20 to 30 years before the onset of symptoms. In theory, we can diagnose prodromal Alzheimer’s disease at any point during those decades. In practice, we have no way to predict when the symptoms will arise or to prevent it from happening, so we do not advise testing people who have normal memory.”

“That said, early detection is critical. The moment you or a loved one have concerns about forgetfulness is when you should seek medical attention,” Hunter told Medical News Today. “The earliest symptoms of Alzheimer’s… lasts about five years and can be quite subtle. Patients can carry out their normal lives during [this period] and may only be identified once they move into dementia – the point in the disease where they need outside care.”

“The reason early detection is critical is that we now have a disease-modifying treatment for Alzheimer’s,” he added. “These are anti-amyloid antibodies. Just as normal antibodies direct your immune system to fight bacteria or viruses, these drugs target the amyloid plaques and cause your body to remove them. These drugs have been in development for over a decade. We have discovered they are only effective at slowing the disease in patients who are very early, in the MCI phase. This is why it is essential we see people as early as possible. The drugs are expensive and have side effects, so we cannot give them to patients who will receive no benefit.”