An AI system using routine MRI scans reports the ability to detect subjective cognitive decline—the earliest preclinical stage of Alzheimer’s—though the work frames performance around clinically pragmatic imaging inputs. In post-acute sequelae, a Dutch multicentre study uses clustering to define four post-COVID symptom patterns; fatigue-dominated groups reported worse outcomes and higher healthcare use at 2.5-year follow-up. On immunological profiling across HIV risk and treatment journeys, plasma proteomics in young people identifies diverging inflammatory signatures, supporting more granular risk stratification as cohorts age and treatment patterns change.