Introduction: Schizophrenia is typically diagnosed through interviews with patients and their relatives. Thus, molecular biomarkers for this mental illness have recently become a hot topic for research. Oxidative stress and antioxidant parameters, such as catalase (CAT), superoxide dismutase (SOD) and malondialdehyde (MDA), have been investigated in schizophrenia; however, no studies have been conducted on the diagnostic performance of oxidative parameters. The goal of the present study is to examine the serum levels of SOD, CAT and MDA and to test the diagnostic performance of MDA in patients with schizophrenia. Methods: Thirty patients with schizophrenia and 30 healthy gender– and age-matched controls were included in our study. Symptom severity in the patient group was rated using the Positive and Negative Syndrome Scale (PANSS). Results: The serum levels of MDA, SOD and CAT were found to be significantly increased in patients with schizophrenia compared to the control group. A receiver operating characteristic curve showed a cut-off point of 2.72 nmol/ml for the MDA diagnostic measure. No significant correlation was found (p>0.05) between MDA, SOD and CAT activity and PANSS scores or the chlorpromazine equivalent and clinical characteristics. Conclusion: In summary, we found higher serum levels of SOD, CAT and MDA in patients with schizophrenia compared to healthy controls. MDA is considered a very good diagnostic lipid peroxidation marker, and further studies should be done to test its validity in patients with schizophrenia.

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Objectives The aim of the study was to investigate the psychometric properties of the Turkish version of Anxiety and preoccupation about sleep questionnaire (APSQ) in clinical and non-clinical samples. Material and Methods Two samples (141 university students and 42 patients with major depressive disorders) completed Turkish APSQ, the Pittsburgh sleep quality index (PSQI), the insomnia severity index (ISI) and the sociodemographic data form. Content validity analysis was performed with the Davis technique after the translation process of the original scale. Explanatory factor analysis and principal component analysis were performed to determine the scales construct validity, and internal consistency and temporal stability analyses were conducted to evaluate its reliability. The PSQI and the insomnia severity index (ISI) were used to assess criterion- related validity. In addition, we divided all the participants into two groups as good-sleepers and clinical insomnia according to ISI scores. Predictive validity analyses were also computed via comparing groups. Results Confirmatory factor analysis showed that the scale model aligns well with the original scales 10 items and two-factor structure. The scales and subdimensions Cronbach’s alpha coefficients were excellent (Factor 1; 0.935, factor 2; 0.906, total scale; 0.952). The test-retest correlations were 0.661 and 0.828 for depression group and university student group, respectively. Turkish APSQ scores were found to be significantly higher in both of the clinical groups (depression group vs. university student group, clinic insomnia group vs. good-sleepers group). Conclusion The Turkish APSQ is adequate reliability and validity for assessing anxiety and preoccupation about sleep in Turkish clinical and non-clinical samples.

We adapted the Ford Insomnia Response to Stress Test to Turkish (FIRST-T) and validated it. Methods: We randomly divided 774 Turkish university students into two equal groups for exploratory (EFA) and confirmatory factor analysis (CFA). McDonald's omega and Cronbach's alpha values were utilized for reliability analyses. Item response theory (IRT) approach also used for psychometric properties on the full sample. For discriminant validity, study sample were classified into high and low sleep reactivity groups, and their sociodemographic and sleep data were compared. Results: EFA results suggested a one-factor structure of the FIRST-T, which was confirmed by CFA results. The FIRST-T had solid internal reliability. Item analysis results showed that all the items could distinguish between low and high scorers. This scale showed the same construct (clinical insomnia vs good sleepers) across the sexes in multi-group CFA and differential item functioning results. In the high FIRST-T score group, sleep quality, severity of insomnia, and anxiety scores were higher. In this group, more participants had clinical insomnia according to the Insomnia Severity Index (ISI) and were poor sleepers according to the Pittsburg Sleep Quality Index (PSQI) (p < 0.01). Conclusion:The FIRST-T has robust psychometric properties that assesses sleep reactivity among university students.

BackgroundInsomniacs are heterogenous group with very diverse personalities. We aimed to investigate the mediating role of sleep reactivity (SR), sleep hygiene (SH), and sleep effort (SE) in the relationship between Type D personality and insomnia.Materials and methodsWe conducted a cross-sectional survey among 474 participants. The survey comprised the sociodemographic data form, Insomnia Severity Index (ISI), D Type Personality Scale (DS-14), Ford Insomnia Response to Stress Test (FIRST), Glasgow Sleep Effort Scale (GSES), and Sleep Hygiene Index (SHI). We conducted hierarchical multiple regression analysis to identify the associations between age, sex, SR, Type D personality traits, SE, SH, and insomnia severity. We subsequently conducted mediation analyses to examine whether SR, SH, and SE mediated the relationship between Type D personality and insomnia.ResultsISI, DS-14, FIRST, SHI, and GSES scores were significantly higher in individuals with Type D personality. Female sex, SR, Type D personality traits, SE, and SH explained 45% of the variance in insomnia severity. When age, sex, insomnia response to stress, and Type D personality traits were controlled, SE and SH significantly explained 25% of the variance in insomnia severity (R2 = 0.45, R2 change = 0.25, F (6.474) = 65.58, p &lt; 0.001). SR, SE, and SH each played a partial mediating role between Type D personality and insomnia.ConclusionThe findings showed that individuals with Type D personality had high SR and that individuals with a higher number of these personality traits exhibited more severe insomnia symptoms through high SR, greater SE, and worse SH.