Early cognitive decline in obstructive sleep apnea (OSA) among men without comorbidities, may be the result of central processes, not associated comorbidities, according to findings from a small study published in the journal Frontiers in Sleep.
OSA has been linked to several cognitive deficits, broadly affecting domains comprised of attention and memory. An increasing body of evidence has cited the concomitant deficits as driven by cardiovascular and metabolic comorbidities, separate from OSA-specific processes. As most individuals with OSA typically present with established comorbidities, it has been difficult to delineate the contribution each specific risk factor has on a persons’ current presentation.
For the study, researchers aimed to characterize the cognitive pattern of a group of middle-aged men who present with OSA without any comorbidities, matched with control individuals.
A cohort of 27 men between the ages of 35 to 70 years, with a diagnosis of OSA and no current or past morbidities, were admitted to be analyzed on a variety of cognitive and neuropsychological parameters. They were compared with a group of healthy-, gender- and education-matched individuals.
Participants underwent respiratory and video-polysomnography testing to reference a baseline of OSA severity. A total of 11 cognitive domains were selected to be evaluated, and they were assessed via 23 automated Cambridge-Neuropsychological-Test-Automated-Battery (CANTAB) tests.
CANTAB tests objectively measured cognition across several related domains that historically affected those with OSA. Tested parameters included reaction time, spatial working memory, pattern recognition, emotional recognition, attention switching, spatial span memory, delayed matching to sample and rapid visual information processing.
A total of 27 patients with OSA and 7 healthy control individuals participated in the study. Group differences were analyzed via 2-way ANCOVA. Age and body mass index (BMI) were included and used as covariates in the study.
Out of 27 patients with OSA, 16 were diagnosed with mild OSA (Apnea Hypoxia Index [AHI] mean (SD, 11.7±4.0 events/h; mean age, 42.6±8.2 years; mean BMI, 26.7±4.1 kg/m2) and 11 with severe OSA (AHI, 41.8±20.7 events/h; age, 46.9±10.9 years; BMI, 28.0±3.2 kg/m2).
When controlling for age and BMI across the 3 experimental groups (control, mild OSA, severe OSA), CANTAB sub-tests found distinct deficits in domains of vigilance, executive functioning, short-term visual recognition memory, and social and emotion recognition. The greatest differences were found between the control and severe OSA group.
Across all cognitive domains, individuals with mild OSA performed better than those with severe OSA, but rarely portrayed deficits that were worse than their controlled counterparts.
Of note, the most significant deficits were found by comparison to the control group in tests that assessed simultaneous visual matching ability and short-term visual recognition memory for nonverbalizable patterns, tests of executive functioning, psychomotor functioning, as well as social cognition and emotion recognition.
Study limitations included the men-only inclusion and the small sample size.
“Our findings suggest that distinct OSA-driven processes, particularly when OSA is severe, may be sufficient for cognitive changes to occur as early as middle age, in otherwise healthy male individuals,” the researchers noted. They concluded, “Future multi-center multi-modal longitudinal studies should confirm these findings, as well as decipher how these cognitive deficits may interplay in men and women with other comorbidity-driven impairments over time.”
This article originally appeared on Neurology Advisor
Gnoni, V, Mesquita M, O’Regan D, et al. Distinct cognitive changes in male patients with obstructive sleep apnoea without comorbidities. Front Sleep. Published online April 6, 2023. https://doi.org/10.3389/frsle.2023.1097946