Test may indicate Alzheimer’s diagnosis 10 years before symptoms begin, study suggests

A new test may optimize the diagnosis of Alzheimer’s within ten years before the onset of symptoms. The causes of neurodegenerative disease are still not fully understood by science, but it is believed to be genetically determined.

In investigations into Alzheimer’s, scientists around the world are working hard to study the so-called biomarkers, which are measurable indicators of the development of a disease.

Researchers from the Karolinska Institutet, in Sweden, have developed a method that can identify a hereditary form of the disease based on blood biomarkers. The results were published in scientific journal Brain.

The progression of Alzheimer’s is associated with the loss of cognitive functions such as memory, language, planning and visual-spatial skills. Early diagnosis of the disease helps to prevent rapid progression.

Recent data from the Ministry of Health indicate that the prevalence in people aged 65 or over corresponds to more than half of the cases. It is estimated that around 1.2 million people live with some form of dementia in Brazil.

The first symptoms may appear a few years before calling the attention of family members, but they are punctual, such as simple forgetting, changing names, repeating the same story and changes in behavior. Recent memory loss is the main warning sign, according to the Ministry of Health.

As it is a progressive disease, the symptoms increase over time and begin to bring irritability, language failures, impaired ability to orient oneself in space and time. In the most severe cases, there is loss of ability to perform everyday tasks.

The disease can also be accompanied by depression, anxiety and apathy. Therefore, early diagnosis increases the chances of delaying the process and preventing the rapid evolution of Alzheimer’s.

The recent study points out that biomarkers present in the blood emerging from Alzheimer’s disease can be non-invasive tools to track early abnormalities related to the disease, such as the accumulation of beta-amyloid proteins, neurofibrillary tangles and mechanisms such as glial activation and neurodegeneration.

However, it is not clear which pathological processes in the central nervous system can be adequately detected by peripheral measurements and whether plasma biomarkers are equally applicable in the clinical and preclinical phases of the disease.

In the study, experts assessed the timing and performance of blood biomarkers in mutation carriers compared to non-carriers in Alzheimer’s disease. 164 samples of blood plasma were analyzed, 33 from people with a mutation that increases the disposition to Alzheimer’s and from 42 relatives who did not have the genetic predisposition.

The results of the analyzes showed that biomarkers indicate the presence of pathological changes early in patients with the disease. The group identified changes in a protein called glial fibrillar acid (GFAP) about ten years before the onset of characteristic symptoms. Specialists also verified increased concentrations of proteins such as tau (P-tau181) and light neurofilament (NfL), related to neuronal damage.

Sampling was performed during the years 1994 to 2018. All biomarkers were analyzed at the Laboratory of Clinical Neurochemistry at Sahlgrenska University Hospital in Mölndal, Sweden. The study’s time frame allowed for the analysis and detection of changes in protein concentrations in the blood of people with the mutation a decade before the onset of signs of the disease.

“Together, P-tau181, GFAP and NfL seem to be viable biomarkers to detect different pathologies related to Alzheimer’s disease already in pre-symptomatic individuals. Interestingly, changes in plasma GFAP concentrations were detected before P-tau181 and NfL. Our results suggest that plasma GFAP may reflect the pathology of Alzheimer’s disease upstream of tangle accumulation and neurodegeneration.