The complexity of the human brain poses a significant challenge to the investigation and hence understanding of the mechanisms governing its function and dysfunction. Digital twins are virtual models designed to reflect physical objects and offer an attractive approach for neuroscience research. The EU-funded eBRAIN-Health project will generate such virtual models of patients and healthy controls to study dementia, an important societal and medical issue. Researchers will process and combine molecular, cellular, physiology and behavioural data into a clinical research infrastructure. Simulating the human brain will assist the prediction of dementia risk as well as the development of health innovations.