Meta-analysis of auditory P50 sensory gating in schizophrenia and bipolar disorder

•Sensory gating examinations with dual-click paradigm showed alteration in P50 sensory gating potential in schizophrenia and bipolar disorder.•S1 and S2 waveforms might be differentially influenced by clinical progress and medications in patients with schizophrenia and bipolar disorder.•P50 sensory gating is altered in schizophrenia and bipolar disorder. Episodes alter P50 sensory gating in bipolar disorder and medications improve sensory gating in both schizophrenia and bipolar disorder.•First-degree relatives had intermediate level sensory gating alteration between patients and healthy controls. The ability of the brain to reduce the amount of trivial or redundant sensory inputs is called gating function. Dysfunction of sensory gating may lead to cognitive fragmentation and poor real-world functioning. The auditory dual-click paradigm is a pertinent neurophysiological measure of sensory gating function. This meta-analysis aimed to examine the subcomponents of abnormal P50 waveforms in bipolar disorder and schizophrenia to assess P50 sensory gating deficits and examine effects of diagnoses, illness states (first-episode psychosis vs. schizophrenia, remission vs. episodes in bipolar disorder), and treatment status (medication-free vs. medicated). Literature search of PubMed between Jan 1st 1980 and March 31st 2019 identified 2091 records for schizophrenia, 362 for bipolar disorder. 115 studies in schizophrenia (4932 patients), 16 in bipolar disorder (975 patients) and 10 in first-degree relatives (848 subjects) met the inclusion criteria. P50 sensory gating ratio (S2/S1) and S1–S2 difference were significantly altered in schizophrenia, bipolar disorder and their first-degree relatives. First-episode psychosis did not differ from schizophrenia, however episodes altered P50 sensory gating in bipolar disorder. Medications improve P50 sensory gating alterations in schizophrenia significantly and at trend level in bipolar disorder. Future studies should examine longitudinal course of P50 sensory gating in schizophrenia and bipolar disorder.