Unveiling New Insights from the Harvard Aging Brain Study
In a recent study published in Neurology titled "Association of Pathologic and Volumetric Biomarker Changes With Cognitive Decline in Clinically Normal Adults," researchers from the Harvard Aging Brain Study have provided new insights into how changes in the brain are related to cognitive decline in older adults.
Background: The Puzzle of the Aging Brain
The hippocampus, a critical region of the brain associated with memory, is known to shrink or atrophy as we age. Traditionally, this atrophy has been linked with memory impairments. However, pinpointing the exact cause of cognitive decline has been challenging so far, especially when considering diseases like Alzheimer's, where factors like β-amyloid (Aβ) plaques and tau tangles are at play.
The Study: A Decade-Long Observation
In this study, researchers followed 283 older adults who initially showed no signs of dementia or cognitive impairment. Over 10 years, the participants underwent various imaging tests, including MRI for measuring hippocampal volume (HV), PET scans to detect Aβ and tau (two proteins associated with Alzheimer's disease), and cognitive assessments.
Key Findings: The Role of Hippocampal Volume
The results revealed something intriguing: while 27% of the participants showed high levels of Aβ, the rate of hippocampal atrophy was independently linked to cognitive decline.
This finding is crucial because it suggests that factors other than just Alzheimer's pathology (like Aβ and tau) could be contributing to memory loss and cognitive decline in older adults.
Some of these factors include:
- Vascular Changes: Reduced blood flow or vascular damage in the brain can contribute to cognitive impairment. This includes conditions like small vessel disease, strokes, or chronic ischemic changes.
- Neuroinflammation: Chronic inflammation in the brain is increasingly recognized as a potential contributor to neurodegeneration and cognitive decline.
- TDP-43 Pathology: TDP-43, a protein previously linked to frontotemporal dementia and ALS, is now also being seen in a subset of elderly individuals, contributing to memory loss and cognitive decline.
- Comorbid Health Conditions: Chronic diseases such as diabetes, hypertension, and obesity can indirectly affect brain health and cognitive functions.
Additional possibilities through AI-based brain volumetry
The published study highlights that hippocampal atrophy is not exclusively an indicator of Alzheimer's pathology but could also indicate other pathologies such as TDP-43 or vascular problems.
This finding is an important step for further research on age-related cognitive decline. It provides new opportunities for establishing prevention strategies and improving existing treatment approaches beyond Alzheimer's disease.
Structural MRI scans have proven to be an important tool for determining the volume of the hippocampus.
It is therefore especially interesting in this context that nowadays AI tools, such as AIRAscore, make it even easier to determine brain volume, including hippocampal volume, even over time.
Association of Pathologic and Volumetric Biomarker Changes With Cognitive Decline in Clinically Normal Adults