An apparatus for measuring a concentration of amyloid-beta within a sample includes signal generation circuitry and a detector. The signal generation circuitry generates a first signal having an applied first orbital angular momentum signature and applies the first signal to the sample. The detector receives the first signal after it passes through the sample and determines the concentration of the amyloid-beta within the sample based on a detected second orbital angular momentum signature within the first signal received from the sample. The detector provides an output of the determined concentration as an indication for determining an early onset of Alzheimer's.