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to have Alzheimer’s changes in the brain or who should be checked for other causes of cognitive change. And, excitingly, it could be used for treatments that don’t yet exist, such as monitoring whether a new drug or perhaps a lifestyle change decreases the presence of amyloid/tau build up. Why not just do a blood test now? The science is more nuanced than ‘finding markers in the blood that reflect Alzheimer’s’. Relying on those results alone can lead to misdiagnosis, says Erin. “For example, how are the markers affected by age, sex, ethnicity, and other conditions such as diabetes? There is more work to be done to align with this complexity.” First, scientists must prove that the test works in New Zealand cohorts, can align with local laboratory platforms, and can be rolled out in a way that’s equitable and cost-effective. At the moment, diagnosing dementia depends on careful observation by a GP or specialist rather than a simple yes or no test. There are some diagnostic tools that can provide biological clues – such as a PET scan or a lumbar puncture – but they’re costly and invasive, and offering them routinely is beyond the capabilities of New Zealand’s medical infrastructure. Blood biomarkers are the logical alternative, but behind that simplicity of a blood test lies complex and cutting-edge science. The magic of microRNA Beyond detecting biomarkers, Associate Professor Joanna Williams’ work reveals another layer of what a blood sample can tell us about Alzheimer’s. Based at the University of Otago, Joanna focuses on identifying tiny molecules called microRNA – genetic messengers circulating in the blood that can reveal with remarkable precision what’s happening in the brain, including signs of inflammation and cell stress. This could be invaluable for tracking whether a treatment is working, and for guiding precision medicine, when therapies are tailored to the molecular make-up of an individual. 6 Headlines Dr Erin Cawston