Medical Scans and Dementia Risk: What the Research Shows
When doctors order brain imaging tests like MRI or PET scans to check for memory problems, many patients wonder if the radiation from these procedures could actually increase their risk of developing dementia. This is a reasonable concern, but the current research does not support a direct link between radiation exposure from medical imaging and higher dementia rates.
The confusion often arises because dementia research frequently mentions brain imaging. However, these scans are tools used to detect dementia risk factors, not causes of dementia themselves. Researchers use imaging to identify warning signs that already exist in the brain, such as amyloid protein buildup or changes in blood vessel function.
Recent studies have focused on what brain scans reveal rather than the scans themselves. For example, researchers have discovered that enlarged perivascular spaces, which are the brain’s drainage channels, can be spotted on routine MRI scans and may indicate early Alzheimer’s disease risk. These findings are valuable because doctors can identify these warning signs without needing additional expensive tests. The imaging helps detect problems that are already developing, but the scan itself is not causing the dementia risk.
Another area of research involves measuring amyloid accumulation in the brain using specialized PET scans. Scientists have tracked how amyloid protein builds up over time in people experiencing early memory concerns. Again, these scans are diagnostic tools that help identify who might be at higher risk, not procedures that create that risk.
The real dementia risk factors that researchers are uncovering include things like disrupted sleep patterns, poor blood vessel health, weak circadian rhythms, and genetic factors. A major study found that people with weaker daily activity rhythms had nearly 2.5 times the risk of developing dementia compared to those with stronger rhythms. Another study showed that controlling high blood pressure could reduce dementia risk even in people with genetic risk factors for the disease.
Sleep quality appears particularly important. Research indicates that people with a weaker glymphatic system, which clears toxic proteins from the brain during sleep, have higher dementia risk. Additionally, moderate to severe sleep apnea has been linked to tiny brain bleeds that could increase dementia chances.
The genetic component also matters significantly. People who carry the APOE e4 gene variant have higher dementia risk, and this risk increases further when combined with biological markers of Alzheimer’s disease detected on brain imaging. However, having these markers does not mean dementia is inevitable, and many people with abnormal biomarkers remain cognitively normal for years.
The key takeaway is that medical imaging scans are valuable diagnostic tools that help doctors identify dementia risk factors already present in the brain. The radiation exposure from these procedures is carefully controlled and monitored by medical professionals. The benefits of detecting early warning signs of cognitive decline far outweigh any theoretical risks from the imaging itself. If a doctor recommends a brain scan to evaluate memory concerns, the scan is meant to help identify treatable or manageable risk factors, not to cause new problems.
Sources
https://pubmed.ncbi.nlm.nih.gov/41240917/
https://www.sciencedaily.com/releases/2025/12/251228020016.htm
