The ABR profiling tests discriminated schizophrenia and ADHD versus healthy controls with high sensitivity and specificity. The methods deserve to be further explored in larger clinical studies including a broad range of psychiatric disorders to determine their utility as potential diagnostic biomarkers.

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.

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AbstractObjective:The aim of the study was to assess whether the auditory brainstem response (ABR) profiling test for schizophrenia (SZ) would recognise schizoaffective disorder (SZA) patients as SZ or not.Method:Male and female SZA patients (n = 16) from the psychosis unit at Uppsala University Hospital were investigated. Coded sets of randomised ABR recordings intermingled with patients with SZ, adult attention-deficit hyperactivity disorder (ADHD) and healthy controls were analysed by an independent party blinded to clinical diagnoses.Results:The ABR profiling test for SZ was positive in 5/16 patients (31%) and negative in 11/16 patients (69%) with SZA. A surprising finding was that 4/16 (25%) SZA patients were positive for the ABR profiling test for ADHD.Conclusion:With the ABR profiling test, a minority of patients with SZA tested positive for SZ. In contrast, a majority (85%) of patients with SZ in a previous study tested positive. These preliminary results leave us ignorant whether SZA should be regarded as a SZ-like disorder or a psychotic mood disorder and add to the questions regarding the validity of this diagnostic entity. However, the ABR profiling method is still in its infancy and its exploration in a range of psychiatric disorders is warranted.