How can your bones tell you about your brain health?
Researchers at Johns Hopkins knew that bone and brain health can both deteriorate with age. They wondered whether the health of one could offer clues about how quickly the other would decline. It might be a way to spot problems in the brain earlier and more easily.
Part of the puzzle is white matter: millions of nerve fibers that act like cables sending electrical messages between regions of the brain.
White matter degrades naturally as we age, and that’s associated with vascular dementia, Alzheimer’s disease and cerebral small vessel disease, which can cause strokes.
Researchers found a routine scan of a completely different part of the body could give us clues about how fast our white matter — and cognition — might degrade down the road.
What researchers aimed to connect white matter results with was bone density — something that can be determined by analyzing results from a routine CT scan. In contrast, the brain MRIs researchers used are much less routinely ordered.
Researchers looked at people who had a non-contrast CT scan done on the chest, a multimodal brain MRI and cognitive testing. They found lower bone density was associated with faster decline in three areas.
First, they looked at data from those MRIs. They found that the lower the bone density in the spine, the more the integrity of the white matter fibers declined as well, specifically in one area responsible for cognition and executive function (planning, organization, emotional regulation).
They also found that lower bone density was associated with faster accumulation of white matter hyperintensities — areas of damaged or abnormal white matter that appear as bright spots on MRI.
These abnormalities become more common with age and are associated with damage to the brain’s small blood vessels, cognitive decline and an increased risk of dementia.
The final finding looked at data from the cognitive testing. People with lower bone density declined faster on cognitive tests. This included examining things like memory, attention, and information processing speed.
Why it matters
One of the most important possibilities raised by the research is that a scan a patient is already getting for an entirely different reason could someday help flag people at greater risk of accelerated brain aging.
“Chest CT is done for lung cancer screening, calcium scoring, nodule follow-up, and many other indications,” author Dr. Sara Momtazmanesh said. “These scans could provide an opportunistic measurement of bone density from the thoracic spine that is associated with a loss of cognitive function.”
To be clear, less bone density doesn’t cause cognitive decline, authors say. The importance of this research is that low bone density could be a marker of broader biological aging, with some of the same underlying processes potentially affecting both bones and the brain. This includes things like inflammation, metabolic dysfunction, and vascular problems.
Identifying people at risk of accelerated cognitive decline earlier could give doctors more time to address and treat risk factors in the patient’s control, such as physical inactivity, high blood pressure and diabetes, and monitor them more closely for changes.
And if further testing ultimately reveals a disease such as Alzheimer’s, early diagnosis is increasingly important. Newer Alzheimer’s medications can slow progression in some people with early-stage disease.
