APOE and Alzheimer disease: Additional analysis of AD Neuroimaging Initiative data revealed that CSF ferritin strongly associated with cognitive decline in APOE-ε4 carriers compared with noncarriers (270); higher baseline CSF ferritin predicted accelerated transition from a normal level of CSF Aβ to a level meeting biomarker criteria for AD (271); furthermore, CSF ferritin also interacts with CSF total-tau/Aβ1-42 ratio to predict brain hypometabolism (reporting reduced brain function and neurodegeneration) (272).