What If the MRI Brain Looks Normal but cognition is not?

“Your scan looks normal.”

For many of my clients, those words are both comforting and devastating. Comforting, because nothing major appears wrong. Devastating, because they still can’t think, focus, or remember the way they used to.

In neuropsychology, we often meet people whose everyday functioning tells a different story from their medical imaging. The MRI captures structure, not experience — and that gap between what’s visible and what’s lived is where the real detective work begins.

Traditional MRI is excellent at detecting structural damage such as bleeding or lesions, but it can’t detect the subtle microstructural changes that can disrupt cognition. For many years, neuropsychological assessment was the only way to demonstrate these invisible changes.

Now, newer imaging techniques are offering a glimpse into those finer details. Diffusion Tensor Imaging (DTI), for example, examines the white matter tracts that connect different brain regions and can reveal disruptions linked to slower processing or memory lapses. Another method, Neurite Orientation Dispersion and Density Imaging (NODDI), measures the density and organisation of the brain’s microscopic wiring, highlighting changes that might underlie difficulties with attention or executive function.

Research shows that even when a standard MRI appears normal, these advanced scans can uncover subtle disorganisation in white matter that correlates with cognitive difficulties. Yet, despite their promise, such methods remain mostly within research labs. They’re rarely available in clinical practice, and their legal acceptance — especially in Australia — is still evolving.

For now, neuropsychological assessment remains the most practical and powerful tool we have for understanding how brain changes affect daily life. Imaging can show us what’s there, but only careful assessment reveals how it feels to live inside that brain — how thinking, remembering, and functioning have changed.

As technology advances, we may one day bridge that divide completely. Until then, our task is to keep listening carefully to people’s lived experiences — because cognition isn’t always visible on a scan.