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Earliest signs of Alzheimer’s may involve changes to the blood flow in the brain

Canadian researchers have carried out a study that suggests that changes to the blood flow within the brain may be one of the earliest indicators of Alzheimer’s disease. The study, which was carried out at the Montreal Neurological Institute, used samples from over 1000 people who were part of the Alzheimer’s Disease Neuroimaging Initiative. The participants were allocated into one of three groups; healthy individuals; those with mild cognitive impairment, and those who had been given a diagnosis of Alzheimer’s.

As the first changes in the brain are known to happen several years before Alzheimer’s symptoms appear, the team wanted to know more about these changes and to find out the order in which they occur. To do so, they analysed brain scans, blood samples and cerebrospinal fluid taken from the participants.

Firstly they examined several different types of brain scan, in order to measure features seen during the progression of the disease. These included the build up of the protein amyloid; changes in the metabolism of glucose; the flow of blood to the brain; the activity of the brain, and changes to the size of the brain. They also looked at the changes within the blood and the cerebrospinal fluid.

By looking at variations of these features within the three groups of participants, it allowed the researchers to map which of the changes was first to appear. In line with results from previous studies, the team found that the build up of amyloid protein was one of the first changes to appear, however their analysis showed that changes in the blood flow to the brain preceded this. This led the researchers to suggest that this disruption could play a major part, and that it could potentially be working with other factors to drive the development of Alzheimer’s.

While it’s long been known that people with Alzheimer’s disease do experience changes in the blood flow to the brain, this particular study puts forward the idea that these changes may happen earlier in the process than we think. Furthermore, it offers potential new evidence about how the disease develops.

To build on these findings, further research needs to be undertaken to enable scientists to gain a better understanding how this disruption to the flow of blood within the brain may link with other Alzheimer’s features, and the way in which it affects how the disease will progress.

The research was published in the journalĀ Nature Communications.

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