There’s been a breakthrough in how we can identify people at risk of Alzheimer’s disease long before any symptoms appear.
Up until now, we’ve depended on MRIs and PET scans of the brain to help doctors look for signs of amyloid plaque, a hallmark of the disease.
But we’re finding that it’s just as important, and perhaps even more valuable, to look at brain blood flow as a predictor — one that it may be possible to do something about…
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Blood flow, not just plaque, can predict Alzheimer’s
Findings of researchers at the Keck School of Medicine at USC hold promise for earlier identification of people at risk of Alzheimer’s disease.
They’ve found that small shifts in how blood moves through the brain and how brain cells receive oxygen may be closely connected to Alzheimer’s risk.
To study these changes, researchers used two simple techniques administered while a person rested quietly:
- Transcranial Doppler ultrasound reveals how quickly blood travels through the brain’s major arteries.
- Near-infrared spectroscopy measures how effectively oxygen reaches brain tissue near the surface of the cortex.
Combining the results of these two procedures gave the researchers an overall indication of cerebrovascular function, including how well the brain adjusts blood flow and oxygen delivery in response to natural fluctuations in blood pressure and carbon dioxide levels.
Among participants whose vascular indicators more closely resembled those of cognitively healthy adults, they observed two features associated with a reduced risk of Alzheimer’s: lower amyloid levels and a larger hippocampus.
In people diagnosed with mild cognitive impairment or dementia, they observed weaker vascular function compared to cognitively normal participants.
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Large-scale screening for early intervention
“These findings add to growing evidence that Alzheimer’s involves meaningful vascular contributions in addition to classic neurodegenerative changes,” said Arthur W. Toga, PhD, director of the Stevens Neuroimaging and Informatics Institute at USC.
“Understanding how blood flow and oxygen regulation interact with amyloid and brain structure opens new doors for early detection and potentially prevention.”
Compared to MRI and PET imaging, the methods used in this study don’t require injections, radiation or complex demands on patients. This makes them ideal for cost-effective large-scale screening.
“If we can track these signals over time, we may be able to identify people at higher risk earlier and test whether improving vascular health can slow or reduce Alzheimer’s-related brain changes,” says Amaryllis A. Tsiknia, lead author of the study and USC PhD candidate.
Supporting the brain’s blood flow
For now, we’d be well advised to do what we can to support our brain’s vascular health. Start by avoiding, reversing, or managing conditions linked to dementia.
These include:
- Heart disease. Plaque buildup in the arteries surrounding your heart is a major cause of heart disease. This can also slow blood flow to your brain. Also, many of the things that cause heart disease, like smoking, diabetes, high blood pressure, and high cholesterol, are also risk factors for dementia.
- Diabetes. Doctors aren’t yet sure why so many people with diabetes go on to develop dementia, and research is ongoing. Blood vessel damage is a complication of diabetes. Therefore, diabetes, especially type 2 diabetes, is considered a risk factor for vascular dementia.
- High Cholesterol. High cholesterol levels in middle age are linked to obesity, high blood pressure and diabetes, all risk factors for vascular dementia. It’s unclear at this point whether high cholesterol itself puts you at risk for dementia later in life.
- High blood pressure. High blood pressure leaves its mark on several brain regions, including 8 specific white matter tracts that connect and enable signaling between different parts of the brain. Many are involved in executive functions, decision-making, and emotion management. High blood pressure may also decrease brain volume.
- Head injury. One fall may not make you more susceptible to dementia. But repeated injuries will.
One factor that impacts most of these conditions is exercise.
People with healthy blood vessels also lead healthy lifestyles that include exercise. Even just walking gets your blood pumping.
Certain foods may also support vascular health…
Researchers at the University of Exeter in England found that older adults who drank blueberry juice every day improved their cognitive scores by 40% and their memory scores by 30%.
But here’s the kicker: MRI scans of those who drank blueberry juice showed increases in both brain blood flow and gray matter activity (neuronal processing).
Sources:
Cerebrovascular regulation dynamics and Alzheimer’s neuroimaging phenotypes — Alzheimer’s and Dementia
Alzheimer’s may begin with a silent drop in brain blood flow — Science Daily
12 ways to keep your brain young — Harvard Health
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