A new method for analyzing auditory brain-stem response waveforms using a moving-minimum subtraction procedure of digitized analog recordings.

The auditory brain-stem response (ABR) waveform comprises a set of waves (labeled I-VII) recorded with scalp electrodes over 10 ms after an auditory stimulation with a brief click sound. Quite often, the waves are fused (confluent) and baseline-irregular and sloped, making wave latencies and wave amplitudes difficult to establish. In the present paper, we describe a method, labeled moving-minimum subtraction, based on digitization of the analog ABR waveform (154 data points/ms) in order to achieve alignment of the ABR response to a straight baseline, often with clear baseline separation of waves and resolution of fused waves. Application of the new method to groups of patients showed marked differences in ABR waveforms between patients with schizophrenia versus patients with adult attention deficit/hyperactivity disorder versus healthy controls. The findings show promise regarding the possibility to identify ABR markers to be used as biomarkers as support for clinical diagnoses of these and other neuropsychiatric disorders.