Distinct cognitive changes in male patients with obstructive sleep apnoea without co-morbidities

Abstract

Introduction: Obstructive sleep apnoea (OSA) is a multisystem, debilitating, chronic disorder of breathing during sleep, resulting in a relatively consistent pattern of cognitive deficits. More recently, it has been argued that those cognitive deficits, especially in middle-aged patients, may be driven by cardiovascular and metabolic comorbidities, rather than by distinct OSA-processes, such as are for example ensuing nocturnal intermittent hypoxaemia, oxidative stress, neuroinflammation, and sleep fragmentation.

Methods: Thus, we undertook to define cognitive performance in a group of 27 middle-aged male patients with untreated OSA, who had no concomitant comorbidities, compared with seven matched controls (AHI mean ± S.D.: 1.9 ± 1.4 events/h; mean age 34.0 ± 9.3 years; mean BMI 23.8 ± 2.3 kg/m²). Of the 27 patients, 16 had mild OSA (AHI mean ± S.D.:11.7 ± 4.0 events/h; mean age 42.6 ± 8.2 years; mean BMI 26.7 ± 4.1 kg/m²), and 11 severe OSA (AHI 41.8 ± 20.7 events/h; age: 46.9 ± 10.9 years, BMI: 28.0 ± 3.2 kg/m²).

Results: In our patient cohort, we demonstrate poorer executive-functioning, visuospatial memory, and deficits in vigilance sustained attention, psychomotor and impulse control. Remarkably, we also report, for the first time, effects on social cognition in this group of male, middle-aged OSA patients.

Conclusion: Our findings suggest that distinct, OSA-driven processes may be sufficient for cognitive changes to occur as early as in middle age, in otherwise healthy individuals.

Keywords: cognition; comorbidity; obstructive sleep apnea; sleep; social memory.

Figure 1

Violin plots depict results of significant CANTAB tests’ findings for controls, mild OSA and severe OSA. When controlled for the influence of age and BMI, out of all CANTAB modalities (23 tests in 11 modalities), only Emotion Recognition Task, Attention Switching Task, Reaction Time and Delayed Matching to Sample showed significant differences between the groups, mainly between controls and severe OSA. Dots, squares and triangles show individual values (control, mild OSA and severe OSA, respectively). Thick dashed lines inside violins indicate group median, with thinner dashed lines indicating quartiles (*P < 0.05, **P < 0.01, ***P < 0.0001; two-way ANCOVA with Bonferroni’s correction for multiple comparisons controlled for age and BMI). RTIFDMRT, Median duration between stimulus onset and release of button; RTIFMMT, Mean time taken to touch stimulus after button release; ERTOMDRT, Median latency of response from stimulus onset to subject response; ERTTH, Number of correctly answered responses; ASTSWMD, Median latency of response in rule switching trials; ASTLCMD, Median latency of response on congruent trials; DMSPC, Percentage of assessment trials during which subject selected the correct box on their first box choice; DMSMDLAD, Median latency from the available choices being displayed to the subject choosing the correct choice.