MAPT and asthma: In our study, non-asthma controls showed expected deleterious effects of age on brain microstructure48,78 that are associated with cognitive decline.99 Further, relationships between CSF biomarkers and brain microstructure were weak or absent among controls, in line with previous reports among amyloid and tau negative CU individuals.74 Thus, the moderating effects of asthma seen in our study suggest that asthma exacerbates the effects of aging and emerging pathology and accelerates the rate of pre-clinical cognitive decline before clinical symptoms are detected.