Do sleep disturbances contribute to cognitive impairments in schizophrenia spectrum and bipolar disorders?

Sleep disturbances and cognitive impairments are both frequent across psychotic disorders, with debilitating effects on functioning and quality of life. This study aims to investigate if sleep disturbances are related to cognitive impairments in schizophrenia spectrum (SCZ) and bipolar disorders (BD), if this relationship varies between different sleep disturbances (insomnia, hypersomnia or delayed sleep phase (DSP)) and lastly, if this relationship differs between clinical groups and healthy controls (HC). We included 797 patients (SCZ = 457, BD = 340) from the Norwegian Centre for Mental Disorders Research (NORMENT) study in Norway. Sleep disturbances were based on items from the Inventory of Depressive Symptoms-Clinician rated scale (IDS-C). Their relationship with several cognitive domains was tested using separate ANCOVAs. A three-way between-groups ANOVA was conducted to test if the relationship with cognitive impairments varies between different sleep disturbances. These analyses revealed significantly poorer processing speed and inhibition in those with any sleep disturbance versus those without, also after adjusting for several covariates. The relationship between sleep disturbances and cognition was similar across SCZ and BD, and there were significant effects of insomnia and hypersomnia on both processing speed and inhibition. No association between sleep disturbances and cognition was found in HC. Sleep disturbances contribute to cognitive impairments in psychotic disorders. Processing speed and inhibition is poorer in patients with sleep disturbances. Impairments in these domains are related to insomnia and hypersomnia. These findings suggest that treating sleep disturbances is important to protect cognitive functioning, alongside cognitive remediation in psychotic disorders.

Social Perception Predicts Awareness of Illness in Persons With Schizophrenia.

Lack of clinical insight in patients with schizophrenia is an obstacle to optimal treatment. Social cognition is one of several variables central to insight deficits in schizophrenia. The aim of this study was to investigate clinical insight in relation to one domain of social cognition, social perception, while controlling for effects of nonsocial cognition and symptom severity. Clinical insight was measured in 55 patients with schizophrenia or schizoaffective disorder, using the Birchwood Insight Scale. Relationships across domains were used to assess social perception. Social perception predicted one of three subscales of clinical insight, "awareness of illness," and was the only unique contributor to this subscale. This indicates that social perception is linked to clinical insight through awareness of illness. More research is needed to fully understand the relationship between social and nonsocial cognition and symptoms in relation to clinical insight.

Sleep disturbances in schizophrenia spectrum and bipolar disorders - a transdiagnostic perspective.

BACKGROUND: Sleep disturbances are prevalent in severe mental disorders but their type and frequency across diagnostic categories has not been investigated in large scale studies. METHODS: Participants with Schizophrenia spectrum disorders (SCZ, (N = 617)), Bipolar disorders (BD, (N = 440)), and Healthy Controls (HC, (N = 173)) were included in the study. Sleep disturbances (insomnia, hypersomnia and delayed sleep phase) were identified based on items from the Inventory of Depressive Symptoms - Clinician rated scale. Clinical symptoms were assessed with the Positive and Negative Syndrome scale and level of functioning with the Global assessment of Functioning scale. RESULTS: The rate of any sleep disturbance was 78% in SZ, 69% in BD and 39% in HC. Insomnia was the most frequently reported sleep disturbance across all groups. Both diagnostic groups reported significantly more of any sleep disturbances than HC (P < 0.001). Having a sleep disturbance was associated with more severe negative and depressive symptoms and with lower functioning across diagnostic groups (P < 0.001, η2 = 0.0071). Hypersomnia was the only sleep disturbance associated with previous treatment history. CONCLUSION: Sleep disturbances, including insomnia, hypersomnia and delayed sleep phase, are frequent in SCZ and BD, and associated with more severe clinical symptomatology across diagnostic groups. This suggests that sleep disturbance is a clinically relevant transdiagnostic phenomenon.

Nicotine use and non-pathological alcohol use and their relationship to affective symptoms and sleep disturbances in bipolar disorder.

BACKGROUND: The use of alcohol and nicotine can negatively impact the course of bipolar disorder (BD), but there is limited knowledge about how symptoms and sleep disturbances are related to concurrent nicotine use and non-pathological use of alcohol. METHODS: We investigated how nicotine use and non-pathological use of alcohol relates to affective symptoms and sleep disturbances in 453 participants with BD without substance use disorders. Manic symptoms were assessed with the Young Mania Rating Scale, and depressive symptoms with The Inventory of Depressive Symptomatology, Clinician-Rated (IDS-C). Sleep-related questions from IDS-C were used to create proxy variables for sleep disturbances, including Insomnia and Hypersomnia. Multinomial regression analysis was conducted to investigate the associations between nicotine use and sleep disturbances, controlling for possible confounders such as current use of illicit drugs and psychopharmacological treatment. RESULTS: Depressive and manic symptoms were not associated with the concurrent level of alcohol or nicotine use. Individuals with medium and high levels of daily nicotine use had higher risk of insomnia than those without. Non-pathological alcohol use was not associated with sleep disturbances. LIMITATIONS: Sleep disturbances were based on items from the IDS-C questionnaire. CONCLUSION: We found an elevated risk for insomnia in individuals with BD and medium or high levels of daily nicotine use. We found no association between the level of affective symptoms and the level of use of alcohol or nicotine. The direction of the relationship between nicotine use and insomnia needs clarification, as it is highly relevant for treatment planning.

Affective lability across psychosis spectrum disorders.

BACKGROUND: Despite apparent clinical remission, individuals with psychotic disorders often experience significant impairments across functional domains. Thus, there is a need to search beyond management of core symptoms to optimize treatment outcomes. Affective dysregulation is considered a risk factor for poor clinical and functional outcomes in many mental disorders, but research investigating such features in psychosis, particularly in schizophrenia, is limited. We aimed to investigate the level of affective lability (AL) in participants with schizophrenia- and bipolar spectrum disorders (n = 222) compared to healthy controls (n = 140), as well as clinical correlates of AL in the diagnostic groups. METHODS: The Affective Lability Scale (ALS-SF) was used to measure total score of AL and subscores covering the domains of anxiety/depression, depression/elation, and anger. An analysis of covariance was performed to compare the ALS-SF total score between groups, correcting for potential confounders, as well as standard multiple regression analyses for diagnosis-specific investigations of the relationship between AL and demographic and clinical features. RESULTS: Both the schizophrenia- and bipolar spectrum group had significantly higher ALS-SF total score compared to controls (p < 0.001), and no significant differences between the patient groups were found. In the schizophrenia group, current psychotic and depressive symptoms were significantly and independently associated with AL (p = 0.012 and p = 0.024, respectively). CONCLUSIONS: The findings indicate that AL is elevated in psychotic disorders and that it transcends diagnostic boundaries. Further research into the causal relationship between psychotic and affective symptoms and AL, as well as its role as a potential therapeutic target in psychosis spectrum disorders, is warranted.

Validity of the Birchwood insight scale in patients with schizophrenia spectrum- and bipolar disorders.

The aim of this study is to investigate the validity of the Norwegian version of the Insight Scale (IS) in large and representative samples of patients with schizophrenia spectrum disorders, bipolar I disorder and bipolar II disorder. A total of 997 participants were included (schizophrenia spectrum disorders: 557; bipolar I disorder: 282; bipolar II disorder: 138). Confirmatory factor analysis was conducted to investigate the construct validity and bivariate correlational analysis was applied to investigate convergent validity. Confirmatory factor analyses indicated a reasonable model fit to the original three-factor subscale structure of the IS in all three diagnostic groups. The IS total score and its subscales correlated significantly with both the insight items in the Young Mania Rating Scale and the Positive and Negative Syndrome Scale in both schizophrenia spectrum disorders and bipolar I disorder. In the bipolar II disorder group, however, the IS subscales correlated poorly with both the observer-rated measures. Our study supports the construct validity of the IS in both schizophrenia spectrum disorder- and bipolar disorder populations. The study also demonstrates that patients' self-reports of insight correspond to observer-based single item ratings of insight in bipolar I disorder and schizophrenia spectrum disorders.