The study of the brain is the study of one of the most important organs behind this story. Alzheimer’s is one of the core diseases neuroscientists spend their careers on, because so much of it still needs explaining.
They look at how amyloid plaques (sticky clumps of protein that build up between brain cells) and tau tangles (twisted fibres that form inside brain cells) build up years before symptoms appear, how those changes show up on a brain scan or in a blood sample as early as ten to fifteen years before the first noticeable memory lapse, and how a diagnosis that once relied on guesswork can now be confirmed with far more precision than before. Neuroscientists work alongside geneticists who study family risk, radiologists who read the imaging, and clinicians who turn all of it into a plan a family can actually use.
Blood tests that can detect Alzheimer’s-related biological changes are now moving from research settings into clinical practice, making earlier detection increasingly possible. One of the more surprising signs researchers are investigating is a change in the sense of smell, which may occur before noticeable memory problems.
Recent research is beginning to uncover why this may happen. A 2025 study implicated early changes in the nerve fibres connecting a small brainstem region called the locus coeruleus with the olfactory system. Microglia, the brain’s resident immune cells, may contribute to the loss of these nerve fibres. These findings offer a possible explanation for why changes in smell may sometimes appear before more obvious symptoms of Alzheimer’s disease.