Scientists have studied the behavior of the brain in Alzheimer's disease

Changes in the brain associated with Alzheimer's disease can occur before noticeable problems with memory and thinking appear. To better understand how these processes develop, scientists compare brain scans with the results of cognitive tests and observe participants over the years. Researchers have compiled a database of thousands of neuroimaging studies that allows them to study brain changes during aging and Alzheimer's disease. What was found out thanks to these data is in the Izvestia article.

Thousands of images and years of observations

Researchers from Washington University in St. Louis presented the KARI database, designed to study brain aging and Alzheimer's disease. The work was published in the journal Nature Communications.

The database includes 6217 brain studies of 1,645 participants aged 42 to 97 years. More than 800 people underwent repeated scans, and some participants were monitored for more than 15 years. The data includes the results of MRI and PET scans, clinical examinations, and memory and thinking tests.

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What the pictures showed

By comparing brain images with the results of cognitive tests, the researchers found a link between more pronounced thinning of the cerebral cortex and poorer performance in memory and thinking. A similar relationship was observed with higher accumulation of beta-amyloid and tau protein, proteins associated with Alzheimer's disease.

MRI allows you to study the structure of the brain, and PET allows you to evaluate the accumulation of certain proteins. The joint analysis of these data helps to investigate how structural and biological changes relate to cognitive functions at different stages of the disease.

Changes before symptoms appear

Not all participants who had Alzheimer's-related biological changes had noticeable cognitive impairments. Among the participants in the database, 1,120 people had a clinical assessment corresponding to the absence of detected disorders, 362 had minimal disorders, 150 had mild dementia, and 11 had moderate dementia.

This allows researchers to study brain changes in people who are not yet experiencing pronounced memory and thinking problems. However, the presence of biological markers in itself does not mean that a person will necessarily develop dementia.

Not only amyloid and tau protein

The database also contains information about vascular changes in the brain, including changes in white matter and micro hemorrhages. The severity of white matter changes increased with age and the level of cognitive impairment. Microbleeds were also more common in participants with cognitive impairments after age was taken into account.

These data make it possible to study not only proteins associated with Alzheimer's disease, but also other brain features that may accompany aging and cognitive decline.

What is important to consider

The KARI database makes it possible to compare scan results with clinical data and monitor brain changes over a long period of time. However, the researchers note limitations: the data was collected over the years using different scanners and imaging techniques, and the participants were predominantly white people with a relatively high level of education.

Therefore, the results should not be automatically transferred to the entire population. The database is intended for further research on aging and Alzheimer's disease, and is not a ready-made diagnostic test.