Can brain scans show how my dementia is causing my memory to fade?

Brain scans can reveal physical changes in your brain that are linked to memory loss in dementia. For example, MRI scans can show shrinkage (atrophy) in areas important for memory, like the hippocampus and medial temporal lobe ⁶¹¹. These changes often correlate with how well your memory functions. However, scans alone cannot fully explain why your memory fades; they are best used alongside other tests, such as cognitive assessments and blood biomarkers, to give a complete picture ¹⁰.

What the research says

Research shows that specific patterns of brain atrophy on MRI are associated with cognitive decline in dementia. A study from the Framingham Heart Study identified components of brain shrinkage that were linked to worse memory and thinking skills over time ⁶. Another study found that breakdown of the blood-brain barrier in the hippocampus, seen on specialized scans, predicted future cognitive decline in people with the APOE4 gene variant ¹¹. This suggests that vascular damage, not just protein buildup, contributes to memory loss.

Blood biomarkers, such as plasma P-tau217, can also indicate Alzheimer's pathology and correlate with brain changes seen on PET scans ⁹. These biomarkers help confirm that the brain changes are due to Alzheimer's disease rather than another cause. A 2025 review highlights that combining brain scans with blood tests allows for a more accurate diagnosis ¹⁰.

While brain scans show structural damage, they do not capture all aspects of memory loss. For instance, dual-task walking studies show that people with dementia have slower, shorter steps when doing a cognitive task, indicating that memory problems also affect movement and coordination ². This suggests that memory loss involves widespread brain networks, not just visible atrophy.

What to ask your doctor

• What type of brain scan (MRI, CT, or PET) would be most helpful for my situation?
• Can you show me the areas of my brain that are affected and explain how they relate to my memory symptoms?
• Should I consider blood tests for Alzheimer's biomarkers to complement the scan results?
• How often should I have follow-up scans to track changes in my brain?
• Are there any lifestyle changes or treatments that might slow the brain changes seen on my scan?