Obstructive sleep apnea syndrome (OSAS) is a sleep disorder characterized with upper airway obstructions. Some studies showed cognitive and electrophysiological changes in patients with OSAS; however, contradictory results were also reported. The purpose of the present study was twofold: (1) to investigate cognitive changes in severe OSAS patients by using neuropsychological tests and electrophysiological methods together, (2) to investigate influence of hypoxemia levels on cognition. Fifty-four severe OSAS patients and 34 age-, gender- and education matched healthy subjects were participated. OSAS patients were further divided into two subgroups according to minimum oxygen saturation levels. All participants underwent a detailed neuropsychological test battery. A classical visual oddball task was used to elicit ERP P300 and mean P300 amplitudes were measured from F, C and P electrode sites. OSAS patients showed reduced mean P300 amplitudes up to 43-51% on all electrode sites compared to healthy controls. Subgroup analysis revealed significant differences in neuropsychological test scores between healthy controls and high hypoxemia OSAS group, as well as between low and high hypoxemia groups. Moreover, both low and high hypoxemia OSAS groups had lower P300 amplitudes compared with healthy controls. P300 amplitudes showed a gradual decline in parallel with increasing hypoxemia severity; however, the difference between high and low hypoxemia OSAS groups did not reach significance. Moderate correlations were found between sleep parameters, neuropsychological test scores and P300 amplitudes. These results suggest that electrophysiological measures could be better indicators of cognitive changes than neuropsychological tests in OSAS, particularly in mildly affected patients.

The major finding of this study was the detection of cognitive changes by electrophysiological methods in PD patients who were indicated to be cognitively normal by neuropsychological tests. These finding suggests that cognitive changes in PD patients, which are not yet reflected in neuropsychological tests, may be detected by electrophysiological methods in earlier stages.

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Background The Timed Up and Go (TUG) test is a simple and widely used clinical test for the assessment of lower extremity function, balance, mobility, and fall risk in various populations. The TUG has been found as a valid and reliable measure in people with Parkinson’s disease (PD). Besides, the addition of a cognitive task to the TUG (TUG-cognitive) enhances predictive validity related to fall risk in people with PD. However, further investigation is needed about the correlations of the TUG-cognitive test with neuropsychological measures in people with PD. Methods Thirty-three people with PD [modified Hoehn and Yahr scale, median (min-max)=2.5 (1.0-3.0)] participated in this cross-sectional study. The TUG was administered in the traditional way and with a cognitive task (counting backward by three from any number between 20 and 100). Neuropsychological measures included the Montreal Cognitive Assessment (MoCA), Trail Making Test (TMT), and the Simple Reaction Time (SRT) test for stepping. The self-reported number of falls in the last six months was also recorded. Results The TUG-cognitive [13.1 (SD=8.5) seconds] was significantly longer than the TUG-traditional [12.2 (SD=8.1) seconds] (p<0.01). The TUG-cognitive significantly correlated with the MoCA [(rho=-0.712), TMT part A (TMT-A; rho=0.722), TMT part B (TMT-B; rho=0.694), SRT (rho=0.794), and number of falls (rho=0.960)] (p<0.01). The TUG-traditional also significantly correlated with the MoCA (rho=-0.682), TMT-A (rho=0.684), TMT-B (rho=0.746), SRT (rho=0.755), and number of falls (rho=0.702) (p<0.01). Conclusion Both the TUG-cognitive and TUG-traditional strongly correlated with neuropsychological measures; while the correlations were slightly stronger for the TUG-cognitive, the difference was not significant. The TUG-cognitive can be used in the clinical practice as a simple and more informative alternative to the TUG-traditional in people with PD.

Objective: The clock drawing test (CDT) version with the pre-drawn circle has been widely used in research and clinical practice without standardized Turkish norms. The present study aimed to standardize CDT scores according to the most frequently used scoring methods in the literature (Manos-Wu and Shulman) and to estimate the validity and reliability of both methods. Materials and Methods: The norm determination phase of the study was performed with 244 healthy individuals in the age range of 50-92 years. The effects of age, education, and sex on the CDT scores were examined and normative data stratified by age and education were derived. Test-retest reliability, inter-rater reliability, and concurrent validity and criterion validity of the two scoring methods were tested. Criterion validity was assessed using the ROC analysis to examine the extent to which the CDT scores could distinguish among healthy individuals, patients with mild cognitive impairment (MCI), and patients with Alzheimer's disease (AD). Results: In the Manos-Wu method, age and education had significant effects on CDT scores of healthy individuals; however, in the Shulman method, only an education effect was found. Both methods had high test-retest reliability (Manos-Wu, 0.81; Shulman, 0.72) and inter-rater reliability (Manos-Wu, 0.98; Shulman, 0.96) and showed high correlations with each other and with other cognitive screening tests. The area under the ROC curve had high values only in discriminating between healthy individuals and AD, and healthy individuals and MCI. Conclusion: In the present study, detailed normative data for individuals aged 50 and older were established. Age and education levels should be taken into account when interpreting CDT scores. Both scoring methods provided similar results in terms of high test-retest and inter-rater reliability, as well as high concurrent and criterion validity.