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. 2014 Oct 7;8:762.
doi: 10.3389/fnhum.2014.00762. eCollection 2014.

Sleep Spindle Deficits in Antipsychotic-Naïve Early Course Schizophrenia and in Non-Psychotic First-Degree Relatives

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Free PMC article

Sleep Spindle Deficits in Antipsychotic-Naïve Early Course Schizophrenia and in Non-Psychotic First-Degree Relatives

Dara S Manoach et al. Front Hum Neurosci. .
Free PMC article

Abstract

Introduction: Chronic medicated patients with schizophrenia have marked reductions in sleep spindle activity and a correlated deficit in sleep-dependent memory consolidation. Using archival data, we investigated whether antipsychotic-naïve early course patients with schizophrenia and young non-psychotic first-degree relatives of patients with schizophrenia also show reduced sleep spindle activity and whether spindle activity correlates with cognitive function and symptoms.

Method: Sleep spindles during Stage 2 sleep were compared in antipsychotic-naïve adults newly diagnosed with psychosis, young non-psychotic first-degree relatives of schizophrenia patients and two samples of healthy controls matched to the patients and relatives. The relations of spindle parameters with cognitive measures and symptom ratings were examined.

Results: Early course schizophrenia patients showed significantly reduced spindle activity relative to healthy controls and to early course patients with other psychotic disorders. Relatives of schizophrenia patients also showed reduced spindle activity compared with controls. Reduced spindle activity correlated with measures of executive function in early course patients, positive symptoms in schizophrenia and IQ estimates across groups.

Conclusions: Like chronic medicated schizophrenia patients, antipsychotic-naïve early course schizophrenia patients and young non-psychotic relatives of individuals with schizophrenia have reduced sleep spindle activity. These findings indicate that the spindle deficit is not an antipsychotic side-effect or a general feature of psychosis. Instead, the spindle deficit may predate the onset of schizophrenia, persist throughout its course and be an endophenotype that contributes to cognitive dysfunction.

Keywords: IQ; cognition; endophenotype; polysomnography; relatives; schizophrenia; sleep; sleep spindles.

Figures

Figure 1
Figure 1
Spectral power plots (A) in schizophrenia patients (SZ) and patients with other psychotic disorders (Others) and (B) in relatives and healthy controls. The left plots show the logarithm of spectral power across the broader 0–30 Hz range. The right plots show 9–16 Hz spectral power with the sigma band (12–15 Hz) EEG power baseline for each group, which was computed as the best fit to the to the 9–10 and 15–16 Hz EEG power baseline. The p-values reflect group differences in sigma power. Asterisks denote significance at p = 0.05.
Figure 2
Figure 2
Spindle parameters in controls and early course patients. Early course patients are divided based on a diagnosis of schizophrenia (SZ) vs. other psychotic disorders (Others). (A) Spindle density; (B) Spindle amplitude. Asterisks denote significance at p = 0.05.
Figure 3
Figure 3
Regressions of cognitive measures on spindle density and amplitude for early course schizophrenia patients (SZ) and those with other psychotic disorders (Others). (A) Shows cognitive measures—Trails B, WCST perseverative errors, and Block Design scaled score—regressed on spindle density. (B) Shows the same cognitive measures regressed on spindle amplitude.
Figure 4
Figure 4
Regressions of WRAT-R Reading standard scores and estimated verbal IQ from the Ammons Quick Test on spindle density and amplitude. (A,B) Early course patients with schizophrenia (SZ) and other psychotic disorders (Others) with regression lines for each group and the pooled group data. (C) Regression of estimated verbal IQ on spindle density and amplitude for the pooled group data from early course schizophrenia, other early course psychotic patients, relatives, and relatives' controls.
Figure 5
Figure 5
Regressions of Scale for the Assessment of Positive Symptoms (SAPS) global total severity scores on spindle amplitude in early course schizophrenia patients.

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