Sleep Spindles: A Comparison in Young Patients with Schizophrenia and Anti-NMDAR Encephalitis

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Building on research indicating a relationship between sleep and schizophrenia, a recent study compared sleep spindle parameters in patients with childhood-onset schizophrenia (COS), early-onset schizophrenia (EOS), anti-NMDAR encephalitis (NMDARE), and healthy control participants.¹ In addition, Dimitriades and colleagues investigated the potential relationship between sleep spindle parameters in patients with COS and EOS and the duration of illness. An understanding of this relationship may lay the foundation for improved novel treatments for patients with schizophrenia.

Dimitriades and colleagues analyzed pooled data from all-night sleep electroencephalogram (EEG) in patients with COS (N = 17, 16.0 ± 3.6 years, 70.6% female), EOS (N = 11, 16.4 ± 1.4 years, 36.4% female), NMDARE (N = 8, 13.3 ± 4.5 years, 75.0% female), and 36 age- and sex-matched control participants in 17 (COS, EOS) or 5 (NMDARE) electrodes. Sleep spindle parameters included sleep spindle density (SSD), maximum amplitude (SSMA), and sigma power (SP).

Sleep spindle parameters were significantly reduced in patients with COS, EOS, and NMDARE compared to the control participants (SSD: t[66] = −5.24, P < 0.00001; SSMA: t[66] = −3.43, P = 0.0011; SP: t[66)]= −4.20, P < 0.0001). Although SSMA and SP were significantly reduced in patients with COS compared to patients with EOS (SSMA: P < 0.0001, 95% CI = [−10.58, −3.49]; SP: P < 0.001, 95% CI = [−4.03, −1.06]) and patients with NMDARE (SSMA: P < 0.0001, 95% CI = [−13.49, −4.79]; SP: P < 0.001, 95% CI = [−4.94, −1.29]), the study failed to discern differences in SSD between the 3 patient groups (F[2, 31] = 2.59, P = 0.091. The study found reduced SP was associated with longer duration of illness in patients with COS and EOS.

“Assessing sleep spindles and their coordination with other oscillations, specifically slow waves, in longitudinal studies may be essential to further discern the pathomechanism of [schizophrenia] and to identify targets for novel interventions to treat this debilitating disorder,” Dimitriades et al concluded.

Several studies suggest that sleep disturbances are exceedingly prevalent in patients with schizophrenia.^2,3 Sleep disturbances are associated with clinical severity, poor clinical outcomes, and suicidal ideation and suicide attempts in patients with schizophrenia.^2,3 Studies have also shown that sleep disturbances often precede the onset of psychotic symptoms.^1-3

Two main oscillatory activities that occur during non-rapid eye movement (NREM) sleep are sleep spindles and slow waves.^2,3 Studies have found impairments in sleep spindles and slow waves in early course and first-episode psychosis.^2,3 Future studies may find sleep spindles and slow waves as biomarkers and treatment targets for schizophrenia and related disorders.^2,3

References

1. Dimitriades ME, Markovic A, Gefferie SR, et al. Sleep spindles across youth affected by schizophrenia or anti- N-methyl-D-aspartate-receptor encephalitis. Front Psychiatry. 2023;14:1055459.

2. Ferrarelli F. Sleep Abnormalities in Schizophrenia: State of the Art and Next Steps. Am J Psychiatry. 2021;178(10):903-913.

3. Zhang Y, Quiñones GM, Ferrarelli F. Sleep spindle and slow wave abnormalities in schizophrenia and other psychotic disorders: Recent findings and future directions. Schizophr Res. 2020;221:29-36.