An observational study in OSA - Obstructive Sleep Apnea and Cognitive Functions, sponsored by Comenius University. Recruiting at 1 site in Slovakia. Open to participants aged 18 Years to 65 Years. Per ClinicalTrials.gov, last updated 2026-01-23.
Sponsored by Comenius University · Observational
Obstructive sleep apnea (OSA) is the most common sleep-related breathing disorder and has been increasingly recognized as a contributor to cognitive decline and a potential risk factor for neurodegeneration. Previous studies have identified several associated comorbidities, including vascular dysfunction, metabolic alterations, and neuroinflammatory changes. However, the impact and underlying interplay of these pathophysiological mechanisms remain poorly understood due to the lack of integrated, multidimensional assessment. This prospective, observational, longitudinal cohort study aims to investigate cognition and OSA-related physiological and pathophysiological processes in 100 adults newly diagnosed with OSA, who have no history of chronic diseases (except for overweight and obesity) and are not receiving chronic medication. A subgroup of patients with moderate to severe OSA indicated for positive airway pressure (PAP) therapy will be followed to evaluate its long-term effects on cognitive function and related mechanisms. All participants will undergo polysomnography (PSG), comprehensive neuropsychological assessment, brain MRI with volumetric analysis, biomarker profiling from blood and saliva, and evaluation of endothelial function, baroreflex sensitivity, and gut microbiome composition at baseline and after 12 months. PAP adherence will be continuously monitored. The primary objective of this study is to characterize the profile of cognitive impairment associated with OSA. Secondary exploratory analyses will focus on factors contributing to neurocognitive dysfunction in OSA.
2,240 studies on the registry are indexed under Sleep Apnea, Obstructive; 475 are open to participants now.
This study's planned enrollment of 30 is below the median of 105 across 666 observational studies indexed under Sleep Apnea, Obstructive.
Browse Sleep Apnea, Obstructive studies →Comenius University is the lead sponsor of 42 studies on the registry; 11 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Patients with newly diagnosed OSA who have no history of other chronic diseases except for overweight and obesity, are not taking any medication, and are aged between 18 and 65 years.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Newly diagnosed OSA according to the criteria of the American Academy of Sleep Medicine Guidelines (overnight PSG with an AHI ≥5 events per hour, hypopneas defined by ≥ 10 seconds of airflow reduction accompanied by ≥ 3% desaturation or an arousal).
Rey Auditory - Verbal Learning Test (RAVLT)
Measure of verbal episodic memory, encompassing immediate recall, learning across trials, delayed recall, and recognition. Units: total number of correctly recalled words (0-75); z-score. Higher scores indicate better performance.
Time frame: Baseline
Figure Copy Task
A visuoconstructional task used to assess visual perception, spatial planning, and visual memory. Units: score 0-24 points; z-score. Higher scores indicate better performance.
Time frame: Baseline
Controlled Oral Word Association Test (COWAT)
A verbal fluency task requiring rapid generation of words beginning with specified letters. It assesses phonemic fluency, executive function, and lexical retrieval. Units: number of correct words generated per minute; z-score. Higher scores indicate better performance.
Time frame: Baseline
Category Fluency Test
A semantic fluency measure where subjects list as many words from a given category. It evaluates semantic memory and executive retrieval processes. Units: number of correct words generated per minute; z-score. Higher scores indicate better performance.
Time frame: Baseline
Trail Making Test (TMT)
A two-part test evaluating processing speed, visual search, attention, and task-switching. Units: completion time in seconds; z-score. Shorter completion times indicate better performance.
Time frame: Baseline
The Stroop Color and Word Test
Measure of selective attention, processing speed, cognitive flexibility, and inhibitory control. Units: completion time in seconds; z-score. Shorter completion times indicate better performance.
Time frame: Baseline
Digit Span
A working memory test comprising forward and backward recall of digit sequences. Assesses attention, concentration, and short-term memory. Units: total score (0-14 points); z-score. Higher scores indicate better performance.
Time frame: Baseline
Montreal Cognitive Assessment (MoCA)
General cognition screening targeting attention, executive function, memory, language, visuospatial abilities, and orientation. Units: total score (0-30 points); ≥26 = normal cognition. Higher scores indicate better performance.
Time frame: Baseline
Generalized Anxiety Disorder 7-item scale (GAD - 7)
A 7-item self-report questionnaire to screen and assess the severity of generalized anxiety disorder. Items are rated on a 4-point scale. Units: total score (0-21 points); cut-off ≥ 10. Higher scores indicate greater anxiety symptom severity.
Time frame: Baseline
Patient´s Health Questionnaire (PHQ - 9)
A 9-item scale assessing depression severity based on DSM IV criteria. Items are rated on a 4-point scale. Units: total score (0-27 points); cut-off ≥ 10. Higher scores indicate greater depressive symptom severity.
Time frame: Baseline
Rey Auditory - Verbal Learning Test (RAVLT) 12 moths
Measure of verbal episodic memory, encompassing immediate recall, learning across trials, delayed recall, and recognition. Units: total number of correctly recalled words (0-75); z-score. Higher scores indicate better performance. Assessments will be performed after 12 months.
Time frame: Change from baseline to 12 months
Figure Copy Task 12 months
A visuoconstructional task used to assess visual perception, spatial planning, and visual memory. Units: score 0-24 points; z-score. Higher scores indicate better performance. Assessments will be performed after 12 months.
Time frame: Change from baseline to 12 months
Controlled Oral Word Association Test (COWAT) 12 months
A verbal fluency task requiring rapid generation of words beginning with specified letters. It assesses phonemic fluency, executive function, and lexical retrieval. Units: number of correct words generated per minute; z-score. Higher scores indicate better performance. Assessments will be performed after 12 months.
Time frame: Change from baseline to 12 months
Category Fluency Test 12 months
A semantic fluency measure where subjects list as many words from a given category. It evaluates semantic memory and executive retrieval processes. Units: number of correct words generated per minute; z-score. Higher scores indicate better performance. Assessments will be performed after 12 months.
Time frame: Change from baseline to 12 months
Trail Making Test (TMT) 12 months.
A two-part test evaluating processing speed, visual search, attention, and task-switching. Units: completion time in seconds; z-score. Shorter completion times indicate better performance. Assessments will be performed after 12 months.
Time frame: Change from baseline to 12 months
The Stroop Color and Word Test 12 months.
Measure of selective attention, processing speed, cognitive flexibility, and inhibitory control. Units: completion time in seconds; z-score. Shorter completion times indicate better performance. Assessments will be performed after 12 months.
Time frame: Change from baseline to 12 months
Digit Span 12 months.
A working memory test comprising forward and backward recall of digit sequences. Assesses attention, concentration, and short-term memory. Units: total score (0-14 points); z-score. Higher scores indicate better performance. Assessments will be performed after 12 months.
Time frame: Change from baseline to 12 months
Montreal Cognitive Assessment (MoCA) 12 months.
General cognition screening targeting attention, executive function, memory, language, visuospatial abilities, and orientation. Units: total score (0-30 points); ≥26 = normal cognition. Higher scores indicate better performance. Assessments will be performed after 12 months.
Time frame: Change from baseline to 12 months
Generalized Anxiety Disorder 7-item scale (GAD - 7) 12 months.
A 7-item self-report questionnaire to screen and assess the severity of generalized anxiety disorder. Items are rated on a 4-point scale. Units: total score (0-21 points); cut-off ≥ 10. Higher scores indicate greater anxiety symptom severity. Assessments will be performed after 12 months.
Time frame: Change from baseline to 12 months
Patient´s Health Questionnaire (PHQ - 9) 12 months.
A 9-item scale assessing depression severity based on DSM IV criteria. Items are rated on a 4-point scale. Units: total score (0-27 points); cut-off ≥ 10. Higher scores indicate greater depressive symptom severity. Assessments will be performed after 12 months.
Time frame: Change from baseline to 12 months
Apnea-Hypopnea Index (AHI)
A polysomnographic measure representing the number of apneas and hypopneas per hour of sleep. Units: events per hour. Higher scores indicate more severe OSA.
Time frame: Baseline
Apnea-Hypopnea Index (AHI) 12 months
A polysomnographic measure representing the number of apneas and hypopneas per hour of sleep. Units: events per hour. Higher scores indicate more severe OSA. Assessments will be performed after 12 months.
Time frame: 12 months
Positive Airway Pressure (PAP) Therapy Adherence
Objective measure of treatment compliance obtained from PAP device data. Units: average hours of use per night. Higher scores indicate better adherence to therapy. Assessments will be performed after 12 months.
Time frame: 12 months
Pittsburgh Sleep Quality Index (PSQI)
A self-rated questionnaire comprising 19 items that evaluate sleep quality and disturbances over a one-month interval. Units: global PSQI score (0-21 points); cut-off ≥ 5. Higher scores indicate poorer overall sleep quality.
Time frame: Change from baseline to 12 months
Epworth Sleepiness Scale (ESS)
An 8-item self-report questionnaire measuring habitual daytime sleepiness in common situations. Units: total score (0-24 points); cut-off ≥ 10. Higher scores indicate greater daytime sleepiness.
Time frame: Change from baseline to 12 months
Brain Volumetry
Quantitative assessment of total and regional brain volumes will include total brain volume, gray and white matter volumes, hippocampal volume, cortical thickness, and other regional volumetric measures. Units: mL; changes in volumes reflect structural brain alterations.
Time frame: Change from baseline to 12 months
Body Mass Index (BMI)
BMI calculated as weight (kg) divided by height squared (m²). Units: kg/m². Higher values indicate greater adiposity.
Time frame: Change from baseline to 12 months
Apolipoprotein E (APOE)
Genotype Genetic biomarker associated with neurodegenerative risk. Units: genotype category (ε2/ε2, ε2/ε3, ε2/ε4, ε3/ε3, ε3/ε4, ε4/ε4). ε4 allele presence indicates higher vulnerability to cognitive decline.
Time frame: Baseline
Plasma Neurofilament Light Chain (pNfL)
A biomarker of neuroaxonal injury. Units: pg/mL. Higher concentrations indicate greater neuronal damage.
Time frame: Change from baseline to 12 months
Total cholesterol
Measure of circulating total cholesterol, representing the combined cholesterol content within all lipoprotein classes. Units: mmol/L. Higher values reflect a more adverse lipid profile.
Time frame: Change from baseline to 12 months
Trolox Equivalent Antioxidant Capacity (TEAC)
Measure of total antioxidant capacity in plasma and saliva. Units: mmol Trolox equivalents/L. Lower TEAC values indicate reduced antioxidant defense and increased susceptibility to oxidative stress.
Time frame: Change from baseline to 12 months
Reactive Hyperemia Index (RHI)
Measure of endothelial function assessed by pulse amplitude tonometry. RHI reflects the vasodilatory response of peripheral arteries following temporary occlusion. Units: ratio. Lower values indicate worse endothelial function.
Time frame: Change from baseline to 12 months
Baroreflex Sensitivity
Indicator of autonomic cardiovascular regulation measured via Finometer. Units: ms/mmHg. Higher values indicate better baroreflex control.
Time frame: Change from baseline to 12 months
Gut Microbiome Composition
Analysis of microbial diversity and abundance from stool samples. Units: Shannon index and Bray-Curtis dissimilarity. Lower alpha diversity and altered beta diversity indicate dysbiosis.
Time frame: Change from baseline to 12 months
Plan to share: No — The study results will present the group as a whole, not individual patient data.
Started Nov 2024 (actual). Primary completion is estimated for Aug 2027, 33 months after the start.
Of 258 non-industry observational studies under Sleep Apnea, Obstructive, half reached primary completion within 31 months of starting (the median), counting those still running; a quarter within 16 and three quarters within 61. This study's planned 33 months is close to that.
Counting every sponsor, half of 294 studies reached it within 28 months; a quarter within 14 and three quarters within 63.
How these figures are worked out, and which studies are left out of them.
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