False memories in obstructive sleep apnoea syndrome: evidence from the divided attention paradigm at encoding or retrieval.

Patients with obstructive sleep apnoea syndrome (OSAS) exhibit impaired retrieval of item-specific information, increasing their propensity to generate false recognitions. The present study investigated the effect of OSAS on false recognition, using a divided-attention paradigm to examine whether reducing the availability of attentional resources during encoding or retrieval in healthy participants mimics the effect of OSAS. We tested four groups of participants, using the Deese - Roediger - McDermott paradigm: patients with OSAS and controls, either under full attention or under divided attention at encoding or retrieval. Results showed that divided attention at retrieval, but not at encoding, mimicked the effects of OSAS on memory performance, as controls in this group exhibited a higher level of false recognition than those under full attention, but a similar level of correct recognition. Our results suggest that the greater susceptibility of patients with OSAS to false recognition may be due to a limited availability of attentional resources, which may specifically disrupt retrieval processes.

Obstructive sleep apnoea syndrome increases source-confusion errors: A pilot study.

We explored external source monitoring (i.e., discrimination between memories of two externally derived sources) in patients with obstructive sleep apnoea syndrome (OSAS). Our specific aim was to ascertain whether, relative to controls, patients exhibit more source-confusion errors when there are similarities between two external memory sources. We recruited 22 patients with OSAS and 22 controls matched for sex, age, and education. The experimental procedure we used came in three phases. First, participants viewed a target film. Second, they were shown a mixed set of photographs, some taken from the film (target photographs), others not (photographs taken from other films not viewed by participants; lures). Lures differed either conceptually or perceptually from the target film. Third, the following day, participants were shown a set of photographs and urged to determine whether the photographs were taken from the target film or whether they were images they had seen for the first time in Phase 2. Patients correctly attributed the same number of target photographs to the target film as controls. By contrast, they incorrectly attributed more lures to the target film than controls did, especially when the lures were semantically similar to the film (perceptual lures). Both perceptual and conceptual source-confusion errors were significantly correlated with oxygen desaturation during sleep. Results suggest that the higher number of source-confusion errors observed in patients with OSAS was linked to an impaired ability to recollect specific perceptual details of the study items and that hypoxia is the main contributing factor to this deficit.

[Obstructive sleep apnea syndrome and cognition: A review]. / Syndrome d'apnées obstructives du sommeil et cognition : une revue.

Obstructive sleep apnea syndrome (OSAS) is a sleep-related breathing disorder characterized by repetitive episodes of airflow cessation, resulting in brief arousals and intermittent hypoxemia. OSAS is associated with a number of adverse health consequences, and cognitive difficulties. The overall pattern of cognitive impairment in OSAS is complex, and research in this field is mixed. On balance, OSAS have negative effects on cognition, most likely in the domain of attention/vigilance, verbal and visual delayed long-term memory, and executive functions. A still unanswered question is whether these deficits are primarily a consequence of sleep fragmentation and/or hypoxemia, or whether they coexist independently from OSAS. Continuous positive airway pressure (CPAP) is the most effective and widely used treatment of OSAS. No consistent effect of CPAP use on cognitive performance was evident. This may be due, in part, to variability in study design and sampling methodology across studies. Structural changes have been reported in different brain regions, particularly in hippocampus and frontal cortex. Recent evidence suggests that the OSAS-related structural changes may improve with CPAP treatment. However, one of the challenges is to interpret the findings in light of comorbid conditions that also cause neural lesions. Animal models will be specifically useful to disentangle the different potential contributors to cognitive impairment in OSAS. The purpose of this article is to provide a review of the literature on cognition and neuroimaging in OSAS patients before and after CPAP treatment. We also discuss the mechanisms that have been proposed to explain cognitive deficits in OSAS patients.