The study found that cerebral blood flow is reduced in the asymptomatic stages of Alzheimer’s disease.

MADRID, 22 years old (EUROPA PRESS)

A multilateral collaboration led by the Barcelona Beta Brain Research Centre (BBRC), a research centre of the Pascual Maragall Foundation, has previously made it possible to measure the reduction in cerebral blood flow in the early stages of Alzheimer’s disease using a new MRI sequence before clinical symptoms appear.

The project, in which Philips Ibérica is involved, involves experts in the development of new magnetic resonance sequences, clinical specialists from Hospital del Mar and collaborators providing cutting-edge biomarkers for Alzheimer’s disease.

The team used a new technique called time-encoded arterial spin labeling (teASL) to detect very early changes in brain blood flow in the study participants. The results, published in the scientific journal Alzheimer’s & Dementia, show that people with the disease also have less blood flow to certain areas of the brain in the early stages.

One of the first processes that is activated in the brain due to the presence of Alzheimer’s pathology (i.e. the accumulation of beta-amyloid and tau proteins) is a decrease in cerebral blood flow. Blood flow provides the brain with oxygen and glucose and therefore must be maintained at a normal level to ensure the health and proper functioning of this organ.

Changes in cerebral blood flow may precede or accompany some neurological conditions, including Alzheimer’s disease, and therefore accurate measurement is vital to understanding these conditions. Arterial spin labeling (ASL) techniques measure cerebral blood flow using MRI pulse sequences.

“Until now, available ASL methods have allowed us to measure and compare cerebral blood flow in people with a ‘single lag time’. This refers to the time it takes for arterial blood to travel from the carotid arteries (where it is ‘flagged’) to the brain area of ​​interest (known as the arterial traffic time),” explains Dr Michalis Kassinopoulos, a BBRC postdoctoral fellow and one of the lead authors of the study. “However, these methods were not optimal for detecting subtle changes in the early stages of the disease, as they were influenced by a variety of factors that influenced the differences in blood transit times between different people and between different brain areas within each person,” he adds.

Through a research collaboration with Philips, BBRC gained access to a new MRI ASL sequence developed by Leiden University Medical Center, known as time-encoded ASL (teASL). This is a more sensitive and accurate tool that reduces arterial transit time differences when assessing cerebral blood flow. The researchers used teASL to measure cerebral blood flow and study its relationship with amyloid and tau pathologies, which are associated with Alzheimer’s disease.

The team also examined how reduced CBF was associated with cerebrospinal fluid biomarkers associated with synaptic dysfunction and neurodegeneration, as well as cognitive performance. The study was thus able to demonstrate for the first time in asymptomatic individuals that CBF levels are associated with markers of tau pathophysiology, synaptic dysfunction, and neurodegeneration.

For this study, a total of 59 participants were divided into three groups: 24 healthy participants without cognitive impairment or accumulation of amyloid protein in the brain (the “control” group); 18 healthy volunteers without cognitive impairment but with amyloid pathology, and 17 patients from the medical research unit of the Hospital del Mar in Barcelona affected by this disease. Of the healthy participants, about thirty are participating in the Alfa study, run by the “la Caixa” foundation.

The study shows that reduced cerebral blood flow is not only seen in people with asymptomatic Alzheimer’s disease, but also in people experiencing cognitive decline with beta-amyloid pathology. “Reduced blood flow is an event in the pathological cascade earlier than previously thought, and spans preclinical stages,” says Dr Juan Domingo Gispert, a BBRC researcher and the study’s author. “These findings provide insight into the role of this early process in the disease and may help shape future prevention strategies,” he concludes.

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