APOE and dementia: These authors found that the relationship between sedentary time and cerebral blood flow in the left hippocampus differs by APOE-4 status, whereby APOE-4 carriers show higher cerebral blood flow as a function of longer sedentary time compared to non-carriers, possibly suggesting a cerebral blood flow regulatory response to compensate for metabolic alterations in dementia risk i.e. blood flow increases due to increased demand for glucose and oxygen to support neuronal activity.