Auditory sensory gating in patients with bipolar disorders: A meta-analysis.

Background: Sensory gating (SG) refers to the attenuation of neural response to the second identical stimulus and is conceptualized as an automatic process to inhibit redundant information. Although its deficit in schizophrenia has been well-documented, the degree to which SG is modulated by bipolar disorders (BD) remains elusive. Thus, the present meta-analysis study aimed to explore the pooled effect sizes of SG ability in BD patients.

Methods: Ten studies consisting of 14 individual investigations were included, consisting of 699 healthy controls and 568 BD patients. The effect sizes, calculated as Cohen's d, were estimated individually for S2/S1 ratio and S1-S2 difference. Additionally, S2/S1 ratio was examined in two conditions: BD with and without a history of psychosis.

Results: We found that BD patients with (d=0.847, p<0.001) or without (d=0.589, p<0.001) a psychotic history exhibited an impaired SG ability compared to the healthy controls. Furthermore, both S1-S2 difference score and S2/S1 ratio, at a group level, can differentiate BD patients from healthy controls.

Limitations: We were not able to divide patients with BD into different subtypes, and thus our data should be interpreted with cautions.

Conclusion: These findings suggest BD itself impairs SG ability, which worsens with a psychotic history. The current understanding invites future research to ascertain the role of SG in subtypes of BD.