1. A computer-implemented method for predicting cognitive decline, comprising: receiving inertial sensor data from one or more inertial sensors attached to a person; receiving, at a time subsequent to receiving the inertial sensor data, data indicative of cognitive function of the person; determining an indication of cognitive decline in the person based on the data indicative of cognitive function; generating a classifier function that associates the inertial sensor data with the indication of cognitive decline in the person, wherein the classifier function is configured to predict whether another person will experience cognitive decline based on inertial sensor data collected from the another person.