Browsing by Author "Yazihan, Naksidil Torun"

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Citation - WoS: 6
Metacognitive beliefs and coping strategies of Suicide Attempters
(Yerkure Tanitim & Yayincilik Hizmetleri A S, 2019) Yazihan, Naksidil Torun; Cinar, Orhan; Canbaz, Hayri; Ak, Mehmet; 276238
Objective: Metacognition is an essential process regarding decision-making and coping with stressful life events. In this present study, we aimed to examine the metacognitive beliefs and coping strategies of suicide attempters with subthreshold depressive symptoms. Methods: Thirty suicide attempters (mean age of 25.50 +/- 7.66 years) with subthreshold depressive symptoms and 30 healthy participants (mean age of 28.27 +/- 7.13 years) were compared with regard to Metacognition Questionnaire-30 (MCQ-30) and COPE Questionnaire. Results: The MANOVA results revealed significant differences between the groups for the subscales of MCQ-30 namely, "negative beliefs about thoughts", "need to control thoughts" and "lack of cognitive confidence". The results also indicated significant difference regarding "positive reinterpretation", "seeking social support for instrumental reasons", "active coping, planning, and problem-focused coping", "behavioral disengagement", "alcohol-drug disengagement" and "dysfunctional coping" subscales of COPE Questionnaire. In addition, moderate correlations were found between the MCQ-30 and the COPE subscales based on the Pearson's correlation coefficients. Conclusions: This study revealed the effect of particular metacognitive beliefs and type of coping style on suicidal behavior. This study is important for identifying risk factors and explaining how metacognitive beliefs and coping strategies are related to suicidal behavior. Maladaptive metacognitions may lead to overestimation of perceived stress and underestimation of cognitive resources and coping skills which may prevent individulas to produce adaptive coping strategies against stressful life events.
Citation - WoS: 0
Citation - Scopus: 0
Sleep spindle-related electroencephalograph activity of young adults and its relation to cognitive functionsc
(Ege Univ, 2019) Yazihan, Naksidil Torun; Yetkin, Sinan; 276238
Objective: Sleep spindles are phasic bursts of thalamocortical activity, typically defined as 11-16 Hz (in sigma frequency band) with a duration of 0.5 and 2 seconds. Spindles are most prominent during N2 sleep and are a defining feature of this stage. The aim of the present study was to investigate the association between spindle characteristics and cognitive functions of young adults. Methods:The study sample consisted of 17 healthy male subjects aged between 19 and 28 years.The participants had no medical or psychological conditions and were not taking any medications that might affect their sleep pattern and neuropsychological measurements. Polysomnography recordings were conducted from 22:30 to 07:00 hour for two subsequent nights. The first night was for adaptation to the laboratory conditions and to rule out sleep apnea syndrome and periodic leg movements. The second night was used to analyze macro and micro parameters of sleep. A neuropsychological test battery comprising the Serial Digit Learning Test, Raven Standard Progressive Matrices, Verbal Fluency Test,Trail Making A-B, and the Auditory Verbal Learning Test were administered before the second-night sleep session. Sleep spindles in all non-rapid eye movement stage 2 sleep were scored visually from C3-A2 electroencephalogram derivation after polysomnographic analysis was completed. Each 30-sec epoch was analyzed with a high-pass band filtered at 0.3 Hz, and a low-pass band filtered at 35 Hz. Spindle characteristics such as duration, amplitude, mean and peak frequencies were analyzed using the fast Fourier transform algorithm. The association between the characteristics of sleep spindles and the neuropsychological test scores were analyzed using Spearman correlations. Results: Significant positive correlations were found between spindle density and both verbal auditory learning performance and verbal fluency, cognitive flexibility, and semantic organization performances. The serial digit learning test was correlated positively with mean duration, mean frequency, and peak frequency of sleep spindles. Finally, the mean duration, and mean frequency of spindles were positively correlated with verbal fluency, cognitive flexibility, and semantic organization. Conclusion: The associations between spindle features and memory, verbal fluency, and verbal learning abilities were consistent with previous research findings suggesting that sleep spindles might be related to cognitive abilities and the potential to learn. In other words, it might be an indicator of the current level of aptitude for learning.
Citation - WoS: 9
Citation - Scopus: 9
Sleep, sleep spindles, and cognitive functions in drug-naive patients with first-episode psychosis
(Amer Acad Sleep Medicine, 2020) Yazihan, Naksidil Torun; Yetkin, Sinan; 276238
Study Objectives: Various lines of clinical findings have suggested abnormalities in macro- or microstructural parameters of sleep in patients with schizophrenia. Meanwhile findings are inconclusive due to some confounding factors, such as the heterogeneity of the disorder, drug regimen, and duration of the illness. There are a few studies in the literature that have been conducted on drug-free patients with first-episode psychosis (FEP). Based on this knowledge, we aimed to explore sleep characteristics, sleep spindles, and neuropsychological profiles of the drug-naive patients with FEP. Methods: The study sample consisted of 21 drug-naive patients with FEP and 21 healthy participants. Polysomnography recordings were conducted for 2 subsequent nights. A neuropsychological test battery was administered for assessing cognitive functions. The Positive and Negative Syndrome Scale was applied to measure symptom severity of the patients. Spindle detection was performed visually. Results: According to the results of the study, the patient group's percentage of stage N2 sleep and sleep efficiency index was lower than in the control group. Among sleep spindle parameters, spindle density was found to be reduced in the patient group. The results of neuropsychological tests measuring executive functions, learning, and memory support the idea that there is a global cognitive deterioration from the early course of the disorder. In the psychotic group, negative symptoms were negatively correlated with verbal memory, learning, verbal fluency, and semantic organization. We found that the percentage of stage N3 sleep decreased while negative symptom severity increased. In addition, the percentage of stage N1 sleep increased as negative symptom severity increased. Reduction in stage N3 sleep was associated with an impairment in learning, verbal fluency, and response inhibition. The sleep spindle density and cognitive functions did not show any associations. Conclusions: Taken together, these findings suggest that patients with FEP show global cognitive impairment (except for attention and processing speed), which is associated with changes in sleep architecture and higher score in a scale assessing negative symptoms. We conclude that cognitive function and spindle parameters differ nonlinearly among patients with FEP.
Citation - WoS: 0
The Relationship Between Sleep and Declarative Memory
(Galenos Publ House, 2018) Yazihan, Naksidil Torun; Yetkin, Sinan; 276238
Sleep is a physiologically active process and the function of cognitive processes is known for a long time. It is also known that sleep has a crucial role in two distinct phases of memory. The first one is the information encoding phase which is prior to the learning process; and the second one is the consolidation phase which is related with the persistency of new information after learning occurs. Consolidation is thought as a function of evolutionarily preserved sleep for many forms of memory. The aim of this review is to get together the main study findings which investigating the relationship between the micro and macro structures of sleep and declarative memory processes. Firstly, definition of sleep is given, and then the specific role of sleep in declarative memory consolidation process is explained. In this context, the projected active system consolidation and synaptic homeostasis hypothesis are explicated. The study results investigating the effects of sleep deprivation on declarative memory and information processing phases are summarized. Finally, the role of sleep spindle and slow wave activity on memory processes, which make up the microstructure of sleep, is discussed.