Scientists find new causes of cognitive decline

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A recent study published in Neurology offers new insights into cognitive decline and its causes beyond the well-known amyloid-beta plaques associated with Alzheimer’s disease.

The study, led by Bernard J. Hanseeuw, MD, Ph.D., of Harvard Medical School, focuses on the hippocampus, a brain region crucial for memory, and its role in cognitive decline.

The research involved 128 participants with an average age of 72, who initially showed no memory or thinking problems.

Over an average follow-up period of seven years, these individuals underwent various brain scans to measure the presence of amyloid plaques and tau tangles, another biomarker of Alzheimer’s, as well as to assess the volume of the hippocampus.

Alongside these scans, they received yearly cognitive evaluations.

One of the key findings of the study was the link between the rate of hippocampal shrinkage and the rate of cognitive decline.

Even in participants who did not have amyloid plaques in the brain, faster shrinkage of the hippocampus was associated with faster cognitive decline.

Remarkably, hippocampal atrophy was found to contribute to cognitive decline independently of amyloid and tau levels, accounting for 10% of the variance in cognitive decline rates.

Dr. Hanseeuw highlighted that these results point to neurodegenerative diseases other than Alzheimer’s as contributing factors to cognitive decline.

He emphasized the importance of measuring hippocampal volume as it could aid in evaluating these other causes, which are currently challenging to measure.

This approach could also improve predictions about who might benefit from new drugs targeting amyloid-beta plaques and individuals’ cognitive decline trajectories.

These findings underscore the complexity of dementia as a condition with multiple underlying causes. The study suggests that types of dementia other than Alzheimer’s disease may be significant contributors to hippocampal shrinkage and cognitive decline.

A notable limitation of the study is its participant demographic, which primarily consisted of highly educated and white individuals. This raises concerns about the generalizability of the findings to a broader population.

Nonetheless, the study marks a significant step in understanding the multifaceted nature of cognitive decline and dementia, highlighting the need to consider factors beyond the traditional biomarkers like amyloid and tau in diagnosing and treating these conditions.

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The research findings can be found in Neurology.

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