OSA - Obstructive Sleep ApneaCUFM1DNNCT07364318
Cognitive Function in Obstructive Sleep Apnea
An observational study of OSA - Obstructive Sleep Apnea and Cognitive Functions, run by Comenius University at 1 site in Slovakia.
Trial summary
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. Read more about this study
- Who is it for?
- Ages 18 to 65 years
- Conditions the study is for
- OSA - Obstructive Sleep Apnea, Cognitive Functions
- How many people
- 30 participants
- Where
- 1 siteSlovakia
- Study dates
- 1 Nov 2024to 31 Dec 2027
- How long will I take part?
- 12 Months
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 65 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: 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.
Who may be able to join
- Informed consent.
- Age 18 - 65 years.
- 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).
- Able to accomplish relevant tests and follow-up.
Who cannot join
- History of any chronic disease other than overweight and obesity.
- Severe psychiatric condition that could affect cognitive functions.
- Chronic use of medication or nicotine that may affect the study results.
- Prior neuropsychological assessment less than 6 months before the start of the research.
- Prior therapy for OSA (i.e., CPAP, upper airway surgery, or oral appliance).
- Motor or sensory deficits that would significantly complicate test administration.
- Patients who do not have Slovak as their native language actively used in daily communication.
- Considered by the study team as not suitable for enrollment based on clinical judgment.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Slovakia1 site, 1 recruiting
- Recruiting
1st Department of Neurology, Faculty of Medicine, Comenius University and University Hospital Bratislava, Slovakia
Bratislava, 813 72
Peter Musil, PhD., +421903836788, peter.musil@fmed.uniba.sk
About this study
Official title: Cognitive Function and Pathophysiological Mechanisms in Adults With Obstructive Sleep Apnea: Long-term Impact of Positive Airway Pressure Therapy
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.
Read the detailed description
- Background OSA is a multifaceted sleep disorder characterized by repeated episodes of upper airway obstruction during sleep, leading to significant reductions in airflow and oxygenation. Beyond its primary respiratory manifestations, OSA is associated with major comorbidities such as cardiovascular, metabolic, and neurocognitive disorders, affecting overall health and quality of life. Epidemiological data suggest that OSA affects nearly one billion individuals worldwide, yet remains markedly underdiagnosed, particularly in middle-aged and older adults. Chronic intermittent hypoxia and sleep fragmentation have been implicated in the disruption of neural networks involved in attention, executive function, memory, and emotion regulation. Neuroimaging studies further support these findings, revealing region-specific brain alterations such as hippocampal and cortical atrophy, white-matter hyperintensities, and changes in cerebral perfusion and metabolism. These mechanisms may contribute to accelerated brain aging and increase the vulnerability to neurodegenerative processes. With the global rise in dementia and aging populations, identifying modifiable contributors to cognitive decline is critical. Given that OSA is a treatable condition, timely diagnosis and effective management may represent one of the most accessible interventions to prevent or delay cognitive deterioration in vulnerable populations.
- Aim of the study The primary aim of this study is to perform a detailed cognitive assessment in patients with OSA. The investigators seek to analyze the baseline prevalence, severity, and pattern of cognitive deficits in this population to gain a clearer understanding of the initial cognitive status from which potential therapeutic or disease-related changes may occur. The secondary aims of this study are exploratory. The investigators plan to investigate potential associations between cognitive impairment and a spectrum of PSG, sleep-related, neuroimaging, anthropometric, laboratory, and vascular measures. The investigators aim to compare the sensitivity of the Montreal Cognitive Assessment (MoCA) with that of a comprehensive neuropsychological battery. Furthermore, the investigators will evaluate the longitudinal effects of PAP therapy on cognition and the related processes under investigation.
- Inclusion criteria 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.
- Study methodology This is a prospective, observational, single-centre cohort study conducted at the Sleep Laboratory of the 1st Department of Neurology, Faculty of Medicine, Comenius University and University Hospital Bratislava. One hundred adults with OSA will be examined at baseline and after 12 months. As part of standard clinical care, all participants will undergo overnight diagnostic PSG to confirm the OSA diagnosis and determine its severity. Patients indicated for PAP therapy will start treatment according to clinical indications, with adherence monitored via device memory cards. Additional research assessments include neuropsychological testing, brain MRI with volumetry, blood and saliva biomarker analysis, assessment of vascular functions, anthropometric measurements, oxidative stress evaluation, and gut microbiome analysis. All assessments will be performed by trained research personnel in a standardized order. Participants will first be hospitalized to undergo PSG to confirm the OSA diagnosis. After confirmation, those meeting the inclusion criteria and providing informed consent will be enrolled in the study.
- What are the possible benefits and risks of participating? Participants may benefit from early detection of cognitive dysfunction, metabolic or vascular abnormalities, and sleep-related pathology. Risks associated with study participation are minimal and primarily related to standard blood sampling and mild discomfort during assessments. No experimental or invasive interventions are applied.
- Conditions
- OSA - Obstructive Sleep Apnea, Cognitive Functions
- Keywords
- Cognitive Function, Positive Airway Pressure Therapy, Obstructive Sleep Apnea, Neuroimaging, Biomarkers, Vascular Changes, Metabolic Changes
- Medical subject headings
- Sleep Apnea, Obstructive
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| Newly diagnosed OSA | 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). |
What is being measured
The primary outcome is the main question the study is designed to answer.
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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: Change from baseline to 12 months
Secondary outcomes (14)
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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: Baseline
Plasma Neurofilament Light Chain (pNfL)
A biomarker of neuroaxonal injury. Units: pg/mL. Higher concentrations indicate greater neuronal damage.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: Change from baseline to 12 months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted23 Jan 2026
- Study start1 Nov 2024
- Primary completion31 Aug 2027 (estimated)
- Study completion31 Dec 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (7)Papers the sponsor has linked to this study.
- Other trials for OSA - Obstructive Sleep ApneaStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 30 participants (estimated)
- Target duration
- 12 Months
Sponsor and investigators
- Lead sponsor
- Comenius University
- Sponsor type
- University, hospital or other
- Collaborators
- University Hospital Bratislava, Slovak Academy of Sciences
- Responsible party
- Sponsor
- Investigators
- Peter Turcani, prof. MD PhD., Study director, 1st Department of Neurology, Faculty of Medicine, Comenius University and University Hospital Bratislava, Slovakia
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07364318
- Sponsor's protocol ID
- CUFM1DN-0111202431122025
- Other IDs
- VEGA 1/0075/25
- Acronym
- CUFM1DN
- Status last verified
- Jan 2026
- First submitted
- 14 Nov 2025
- Last updated
- 23 Jan 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: The study results will present the group as a whole, not individual patient data.
Publications
Sehr T, Akgun K, Benkert P, Kuhle J, Ziemssen T, Brandt MD. Effects of obstructive sleep apnea treatment on neurodegenerative biomarker neurofilament light chain and cognitive performance. J Sleep Res. 2024 Oct;33(5):e14164. doi: 10.1111/jsr.14164. Epub 2024 Feb 13.
PubMed 38351662Xue X, Zhao Z, Zhao LB, Gao YH, Xu WH, Cai WM, Chen SH, Li TJ, Nie TY, Rui D, Ma Y, Qian XS, Lin JL, Liu L. Gut microbiota changes in healthy individuals, obstructive sleep apnea patients, and patients treated using continuous positive airway pressure: a whole-genome metagenomic analysis. Sleep Breath. 2024 Nov 26;29(1):11. doi: 10.1007/s11325-024-03185-z.
PubMed 39589660Silva WA, Almeida-Pititto B, Santos RB, Aielo AN, Giatti S, Parise BK, Souza SP, Vivolo SF, Lotufo PA, Bensenor IM, Drager LF. Obstructive sleep apnea is associated with lower adiponectin and higher cholesterol levels independently of traditional factors and other sleep disorders in middle-aged adults: the ELSA-Brasil cohort. Sleep Breath. 2021 Dec;25(4):1935-1944. doi: 10.1007/s11325-021-02290-7. Epub 2021 Feb 15.
PubMed 33590375Salari N, Khazaie H, Abolfathi M, Ghasemi H, Shabani S, Rasoulpoor S, Mohammadi M, Rasoulpoor S, Khaledi-Paveh B. The effect of obstructive sleep apnea on the increased risk of cardiovascular disease: a systematic review and meta-analysis. Neurol Sci. 2022 Jan;43(1):219-231. doi: 10.1007/s10072-021-05765-3. Epub 2021 Nov 19.
PubMed 34797460Durtette A, Dargent B, Gierski F, Barbe C, Deslee G, Perotin JM, Henry A, Launois C. Impact of continuous positive airway pressure on cognitive functions in adult patients with obstructive sleep apnea: A systematic review and meta-analysis. Sleep Med. 2024 Nov;123:7-21. doi: 10.1016/j.sleep.2024.08.019. Epub 2024 Aug 22.
PubMed 39226674Bubu OM, Andrade AG, Umasabor-Bubu OQ, Hogan MM, Turner AD, de Leon MJ, Ogedegbe G, Ayappa I, Jean-Louis G G, Jackson ML, Varga AW, Osorio RS. Obstructive sleep apnea, cognition and Alzheimer's disease: A systematic review integrating three decades of multidisciplinary research. Sleep Med Rev. 2020 Apr;50:101250. doi: 10.1016/j.smrv.2019.101250. Epub 2019 Dec 12.
PubMed 31881487Xu H, Liu Y, Li C, Li X, Shen L, Wang H, Liu F, Zou J, Xia Y, Huang W, Liu Y, Gao Z, Fu Y, Wang F, Huang S, Song Z, Song F, Gao Y, Peng Y, Zou J, Zhu H, Liu S, Li L, Zhu X, Xiong Y, Hu Y, Yang J, Li Y, Gao F, Guo Q, Huang H, Zhang W, Li J, Chen Y, Dong P, Yang J, Lv J, Wang P, Sun Y, Qian B, Yaffe K, Guan J, Yi H, Leng Y, Yin S. Effects of Continuous Positive Airway Pressure on Neuroimaging Biomarkers and Cognition in Adult Obstructive Sleep Apnea: A Randomized Controlled Trial. Am J Respir Crit Care Med. 2025 Apr;211(4):628-636. doi: 10.1164/rccm.202406-1170OC.
PubMed 39998447
Study at a glance
From the registry record, last updated by the sponsor on 23 Jan 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Cognitive Function and Pathophysiological Mechanisms in Adults With Obstructive Sleep Apnea: Long-term Impact of Positive Airway Pressure Therapy
- ClinicalTrials.gov ID
- NCT07364318
- Acronym / sponsor ID
- CUFM1DN / CUFM1DN-0111202431122025
- Conditions
- OSA - Obstructive Sleep Apnea, Cognitive Functions
- Keywords
- Cognitive Function, Positive Airway Pressure Therapy, Obstructive Sleep Apnea, Neuroimaging, Biomarkers, Vascular Changes, Metabolic Changes
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 30 participants (estimated)
- Lead sponsor
- Comenius UniversityUniversity, hospital or other
- Collaborators
- University Hospital Bratislava, Slovak Academy of Sciences
- Study start
- 1 Nov 2024 (actual)
- Primary completion
- 31 Aug 2027 (estimated)
- Study completion
- 31 Dec 2027 (estimated)
- First posted
- 23 Jan 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Detailed description
- Background OSA is a multifaceted sleep disorder characterized by repeated episodes of upper airway obstruction during sleep, leading to significant reductions in airflow and oxygenation. Beyond its primary respiratory manifestations, OSA is associated with major comorbidities such as cardiovascular, metabolic, and neurocognitive disorders, affecting overall health and quality of life. Epidemiological data suggest that OSA affects nearly one billion individuals worldwide, yet remains markedly underdiagnosed, particularly in middle-aged and older adults. Chronic intermittent hypoxia and sleep fragmentation have been implicated in the disruption of neural networks involved in attention, executive function, memory, and emotion regulation. Neuroimaging studies further support these findings, revealing region-specific brain alterations such as hippocampal and cortical atrophy, white-matter hyperintensities, and changes in cerebral perfusion and metabolism. These mechanisms may contribute to accelerated brain aging and increase the vulnerability to neurodegenerative processes. With the global rise in dementia and aging populations, identifying modifiable contributors to cognitive decline is critical. Given that OSA is a treatable condition, timely diagnosis and effective management may represent one of the most accessible interventions to prevent or delay cognitive deterioration in vulnerable populations.
- Aim of the study The primary aim of this study is to perform a detailed cognitive assessment in patients with OSA. The investigators seek to analyze the baseline prevalence, severity, and pattern of cognitive deficits in this population to gain a clearer understanding of the initial cognitive status from which potential therapeutic or disease-related changes may occur. The secondary aims of this study are exploratory. The investigators plan to investigate potential associations between cognitive impairment and a spectrum of PSG, sleep-related, neuroimaging, anthropometric, laboratory, and vascular measures. The investigators aim to compare the sensitivity of the Montreal Cognitive Assessment (MoCA) with that of a comprehensive neuropsychological battery. Furthermore, the investigators will evaluate the longitudinal effects of PAP therapy on cognition and the related processes under investigation.
- Inclusion criteria 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.
- Study methodology This is a prospective, observational, single-centre cohort study conducted at the Sleep Laboratory of the 1st Department of Neurology, Faculty of Medicine, Comenius University and University Hospital Bratislava. One hundred adults with OSA will be examined at baseline and after 12 months. As part of standard clinical care, all participants will undergo overnight diagnostic PSG to confirm the OSA diagnosis and determine its severity. Patients indicated for PAP therapy will start treatment according to clinical indications, with adherence monitored via device memory cards. Additional research assessments include neuropsychological testing, brain MRI with volumetry, blood and saliva biomarker analysis, assessment of vascular functions, anthropometric measurements, oxidative stress evaluation, and gut microbiome analysis. All assessments will be performed by trained research personnel in a standardized order. Participants will first be hospitalized to undergo PSG to confirm the OSA diagnosis. After confirmation, those meeting the inclusion criteria and providing informed consent will be enrolled in the study.
- What are the possible benefits and risks of participating? Participants may benefit from early detection of cognitive dysfunction, metabolic or vascular abnormalities, and sleep-related pathology. Risks associated with study participation are minimal and primarily related to standard blood sampling and mild discomfort during assessments. No experimental or invasive interventions are applied.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Target follow-up
- 12 Months
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Newly diagnosed OSA | – | –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). |
Who may qualify
- Ages
- 18 to 65 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- 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.
Key inclusion criteria (4 listed)
- Informed consent.
- Age 18 - 65 years.
- 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).
- Able to accomplish relevant tests and follow-up.
Key exclusion criteria (8 listed)
- History of any chronic disease other than overweight and obesity.
- Severe psychiatric condition that could affect cognitive functions.
- Chronic use of medication or nicotine that may affect the study results.
- Prior neuropsychological assessment less than 6 months before the start of the research.
- Prior therapy for OSA (i.e., CPAP, upper airway surgery, or oral appliance).
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
Rey Auditory - Verbal Learning Test (RAVLT)
Time frame: Baseline
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.
Figure Copy Task
Time frame: Baseline
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.
Controlled Oral Word Association Test (COWAT)
Time frame: Baseline
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.
Category Fluency Test
Time frame: Baseline
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.
Trail Making Test (TMT)
Time frame: Baseline
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.
The Stroop Color and Word Test
Time frame: Baseline
Measure of selective attention, processing speed, cognitive flexibility, and inhibitory control. Units: completion time in seconds; z-score. Shorter completion times indicate better performance.
Digit Span
Time frame: Baseline
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.
Montreal Cognitive Assessment (MoCA)
Time frame: Baseline
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.
Generalized Anxiety Disorder 7-item scale (GAD - 7)
Time frame: Baseline
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.
Patient´s Health Questionnaire (PHQ - 9)
Time frame: Baseline
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.
Rey Auditory - Verbal Learning Test (RAVLT) 12 moths
Time frame: Change from baseline to 12 months
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.
Figure Copy Task 12 months
Time frame: Change from baseline to 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.
Controlled Oral Word Association Test (COWAT) 12 months
Time frame: Change from baseline to 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.
Category Fluency Test 12 months
Time frame: Change from baseline to 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.
Trail Making Test (TMT) 12 months.
Time frame: Change from baseline to 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.
The Stroop Color and Word Test 12 months.
Time frame: Change from baseline to 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.
Digit Span 12 months.
Time frame: Change from baseline to 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.
Montreal Cognitive Assessment (MoCA) 12 months.
Time frame: Change from baseline to 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.
Generalized Anxiety Disorder 7-item scale (GAD - 7) 12 months.
Time frame: Change from baseline to 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.
Patient´s Health Questionnaire (PHQ - 9) 12 months.
Time frame: Change from baseline to 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.
14 secondary outcomes
Apnea-Hypopnea Index (AHI)
Time frame: Baseline
Apnea-Hypopnea Index (AHI) 12 months
Time frame: 12 months
Positive Airway Pressure (PAP) Therapy Adherence
Time frame: 12 months
Pittsburgh Sleep Quality Index (PSQI)
Time frame: Change from baseline to 12 months
Epworth Sleepiness Scale (ESS)
Time frame: Change from baseline to 12 months
Brain Volumetry
Time frame: Change from baseline to 12 months
Body Mass Index (BMI)
Time frame: Change from baseline to 12 months
Apolipoprotein E (APOE)
Time frame: Baseline
Plasma Neurofilament Light Chain (pNfL)
Time frame: Change from baseline to 12 months
Total cholesterol
Time frame: Change from baseline to 12 months
Trolox Equivalent Antioxidant Capacity (TEAC)
Time frame: Change from baseline to 12 months
Reactive Hyperemia Index (RHI)
Time frame: Change from baseline to 12 months
Baroreflex Sensitivity
Time frame: Change from baseline to 12 months
Gut Microbiome Composition
Time frame: Change from baseline to 12 months
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 23 Jan 2026.
- Results publication: PubMed 38351662Sehr T, Akgun K, Benkert P, Kuhle J, Ziemssen T, Brandt MD. Effects of obstructive sleep apnea treatment on neurodegenerative biomarker neurofilament light chain and cognitive performance. J Sleep Res. 2024 Oct;33(5):e14164. doi: 10.1111/jsr.14164. Epub 2024 Feb 13.
- Results publication: PubMed 39589660Xue X, Zhao Z, Zhao LB, Gao YH, Xu WH, Cai WM, Chen SH, Li TJ, Nie TY, Rui D, Ma Y, Qian XS, Lin JL, Liu L. Gut microbiota changes in healthy individuals, obstructive sleep apnea patients, and patients treated using continuous positive airway pressure: a whole-genome metagenomic analysis. Sleep Breath. 2024 Nov 26;29(1):11. doi: 10.1007/s11325-024-03185-z.
- Results publication: PubMed 33590375Silva WA, Almeida-Pititto B, Santos RB, Aielo AN, Giatti S, Parise BK, Souza SP, Vivolo SF, Lotufo PA, Bensenor IM, Drager LF. Obstructive sleep apnea is associated with lower adiponectin and higher cholesterol levels independently of traditional factors and other sleep disorders in middle-aged adults: the ELSA-Brasil cohort. Sleep Breath. 2021 Dec;25(4):1935-1944. doi: 10.1007/s11325-021-02290-7. Epub 2021 Feb 15.
- Results publication: PubMed 34797460Salari N, Khazaie H, Abolfathi M, Ghasemi H, Shabani S, Rasoulpoor S, Mohammadi M, Rasoulpoor S, Khaledi-Paveh B. The effect of obstructive sleep apnea on the increased risk of cardiovascular disease: a systematic review and meta-analysis. Neurol Sci. 2022 Jan;43(1):219-231. doi: 10.1007/s10072-021-05765-3. Epub 2021 Nov 19.
- Results publication: PubMed 39226674Durtette A, Dargent B, Gierski F, Barbe C, Deslee G, Perotin JM, Henry A, Launois C. Impact of continuous positive airway pressure on cognitive functions in adult patients with obstructive sleep apnea: A systematic review and meta-analysis. Sleep Med. 2024 Nov;123:7-21. doi: 10.1016/j.sleep.2024.08.019. Epub 2024 Aug 22.
- Results publication: PubMed 31881487Bubu OM, Andrade AG, Umasabor-Bubu OQ, Hogan MM, Turner AD, de Leon MJ, Ogedegbe G, Ayappa I, Jean-Louis G G, Jackson ML, Varga AW, Osorio RS. Obstructive sleep apnea, cognition and Alzheimer's disease: A systematic review integrating three decades of multidisciplinary research. Sleep Med Rev. 2020 Apr;50:101250. doi: 10.1016/j.smrv.2019.101250. Epub 2019 Dec 12.
- Results publication: PubMed 39998447Xu H, Liu Y, Li C, Li X, Shen L, Wang H, Liu F, Zou J, Xia Y, Huang W, Liu Y, Gao Z, Fu Y, Wang F, Huang S, Song Z, Song F, Gao Y, Peng Y, Zou J, Zhu H, Liu S, Li L, Zhu X, Xiong Y, Hu Y, Yang J, Li Y, Gao F, Guo Q, Huang H, Zhang W, Li J, Chen Y, Dong P, Yang J, Lv J, Wang P, Sun Y, Qian B, Yaffe K, Guan J, Yi H, Leng Y, Yin S. Effects of Continuous Positive Airway Pressure on Neuroimaging Biomarkers and Cognition in Adult Obstructive Sleep Apnea: A Randomized Controlled Trial. Am J Respir Crit Care Med. 2025 Apr;211(4):628-636. doi: 10.1164/rccm.202406-1170OC.
- Individual participant dataSharing planned: No. The study results will present the group as a whole, not individual patient data.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Peter Turcani, prof. MD PhD. study director
1st Department of Neurology, Faculty of Medicine, Comenius University and University Hospital Bratislava, Slovakia
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of OSA - Obstructive Sleep Apnea and Cognitive Functions, run by Comenius University at 1 site in Slovakia.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 8 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 23 Jan 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Slovakia. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Branislav Kollar, prof. MD PhD. MPH. (+421 948 334 417, b.kollar.md@gmail.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Rey Auditory - Verbal Learning Test (RAVLT) (time frame: Baseline). The study lists 20 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT07364318, which also lists 7 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 23 Jan 2026.