A system for determining an acute brain function impairment of a subject, the system comprising: a sensor system with at least 20 channels configured to acquire signals indicative of a function of a brain of the subject; wherein sensors (106, 304) of the sensor system are near infrared spectroscopy, NIRS, sensors or functional near infrared spectroscopy, fNIRS, sensors; a processor configured to receive the signals from at least one sensor of the sensor system and configured to: analyze the signals to determine an amount of functional connectivity between portions of the brain of the subject from the signals, comprising creating a correlation matrix, wherein correlations of signals from the channels are computed to measure coupling across channel pairs; compare the amount of functional connectivity between portions of the brain of the subject to a reference amount of functional connectivity, comprising creating a correlation change matrix using the created correlation matrix processed against the reference amount of functional connectivity by performing a subtraction of the correlation matrix of the reference amount of functional connectivity from the correlation matrix of the amount of functional connectivity; determine an acute impairment of the subject based on the comparison of the amount of functional connectivity between portions of the brain of the subject to the reference amount of functional connectivity using the correlation change matrix; and generate a report indicating the acute impairment of the subject; wherein the at least one sensor is configured to acquire the signals from the prefrontal cortex; wherein the sensor system comprises at least one additional sensor, being configured to acquire signals from an area of the brain outside the prefrontal cortex; wherein the reference amount of functional connectivity is determined from the signals acquired from the prefrontal cortex. a sensor system with at least 20 channels configured to acquire signals indicative of a function of a brain of the subject; wherein sensors (106, 304) of the sensor system are near infrared spectroscopy, NIRS, sensors or functional near infrared spectroscopy, fNIRS, sensors; a processor configured to receive the signals from at least one sensor of the sensor system and configured to: analyze the signals to determine an amount of functional connectivity between portions of the brain of the subject from the signals, comprising creating a correlation matrix, wherein correlations of signals from the channels are computed to measure coupling across channel pairs; compare the amount of functional connectivity between portions of the brain of the subject to a reference amount of functional connectivity, comprising creating a correlation change matrix using the created correlation matrix processed against the reference amount of functional connectivity by performing a subtraction of the correlation matrix of the reference amount of functional connectivity from the correlation matrix of the amount of functional connectivity; determine an acute impairment of the subject based on the comparison of the amount of functional connectivity between portions of the brain of the subject to the reference amount of functional connectivity using the correlation change matrix; and generate a report indicating the acute impairment of the subject; analyze the signals to determine an amount of functional connectivity between portions of the brain of the subject from the signals, comprising creating a correlation matrix, wherein correlations of signals from the channels are computed to measure coupling across channel pairs; compare the amount of functional connectivity between portions of the brain of the subject to a reference amount of functional connectivity, comprising creating a correlation change matrix using the created correlation matrix processed against the reference amount of functional connectivity by performing a subtraction of the correlation matrix of the reference amount of functional connectivity from the correlation matrix of the amount of functional connectivity; determine an acute impairment of the subject based on the comparison of the amount of functional connectivity between portions of the brain of the subject to the reference amount of functional connectivity using the correlation change matrix; and generate a report indicating the acute impairment of the subject; wherein the at least one sensor is configured to acquire the signals from the prefrontal cortex; wherein the sensor system comprises at least one additional sensor, being configured to acquire signals from an area of the brain outside the prefrontal cortex; wherein the reference amount of functional connectivity is determined from the signals acquired from the prefrontal cortex.