1. A method comprising: receiving, using electrodes, a baseline measurement corresponding to a representation of brain activity from a living body; storing the baseline measurements on a storage device configured to be wearable on the living body; obtaining, using electrodes connected to a portable device, at a time subsequent to the baseline measurement, a second measurement representing brain activity from the living body; evaluating, via a processing unit of the portable device, the living body based on a comparison of the second measurement to the baseline measurement stored in the storage device, wherein the storage device is portable independently of the portable device; determining, via the processing unit of the portable device, whether the second measurement is indicative of a persistent change in the brain activity of the living body; replacing, via one of the portable device and a docking station, the baseline measurement with a current measurement if the second measurement is indicative of a persistent change in the brain activity of the living body; and determining, via the processing unit, if the living body is experiencing an impairment based on the comparison of the baseline data to the current brain activity data, wherein if an impairment is detected, the processing unit prevents operation of a machine operably associated with the system.