P031 Does obstructive sleep apnea severity impact sleep spindles in schizophrenia?

Abstract Introduction Patients with schizophrenia have a high prevalence of obstructive sleep apnea (OSA). Sleep disturbance and sleep spindle deficits are observed in both schizophrenia and OSA patients. But whether the spindle deficits seen in schizophrenia are modified across a broad spectrum of OSA severity remains unclear Methods We analysed overnight electrocephalography (EEG) from schizophrenia patients with suspected OSA (n=29, mean age=44 yrs, gender (F:M) = 7:22, AHI range=0.0-123.4/hr) and a non-schizophrenia control group (n=29, mean age=44 yrs, gender (F:M) = 7:22, AHI range=8.6-106.6/hr) selected with a similar age and gender distribution. Sleep spindles (11-16Hz) were identified using a validated automated algorithm at a central EEG electrode site. A linear regression model was used to assess the differences between people with and without schizophrenia and examine the association between OSA severity (Apnea-Hypopnea Index; AHI) and its interaction with schizophrenia. Results The schizophrenia group had lower NREM sleep spindle density compared with controls (0.6/min vs 1.8/mins; p<0.05). Sleep apnea severity (AHI) was not associated with spindle density, schizophrenia did not modify this association. We incidentally observed that the schizophrenia group had increased N1 (58.4 vs 15.0 minutes) and N3 (85.7 vs 25.1 minutes) sleep, and reduced N2 (195.7 vs 250.8 minutes) and REM (46.5 vs 69.0 minutes) sleep (all p<0.05). Conclusion Our preliminary findings suggest that sleep spindle deficits observed in schizophrenia are not further impaired by OSA severity. Future research exploring the possible therapeutic effects of OSA treatment on sleep spindles and restoring sleep architecture in schizophrenia are now warranted.