False memories in patients suffering from obstructive sleep apnoea syndrome (OSAS)

Reversible Verbal Memory Integration Deficits in Obstructive Sleep Apnoea

When presented with novel but semantically related elements after learning verbal material, healthy participants tend to endorse these items as previously learned. This reflects the normal integration and association of novel verbal information into long-term memory. How obstructive sleep apnoea (OSA) negatively impacts verbal memory performance, and whether deficits are reversible following positive airway pressure (PAP) treatment, remain elusive. We investigated immediate and delayed OSA- and PAP treatment-related effects on verbal memory integration, using a false memory paradigm. Twenty-three patients with OSA learned lists of words semantically related to target non-presented words (1) at baseline after a polysomnography diagnosis night, (2) after a consecutive polysomnography night under PAP titration, and (3) after three months of compliant PAP treatment. At each session, participants learned 10 different lists of words, each list comprising 15 semantically related items. They had then to recognize 15 minutes later (after an intermediate vigilance task) previously learned words within a list including studied words (learned), unstudied but semantically related items (lures), and non-related unstudied items (controls). Sleep quality and fatigue questionnaires, and psychomotor vigilance tests (PVT) were administered at each session. PAP treatment led to OSA remission and improvement in objective and subjective sleep quality. Crucially, recognition of learned and lure words increased after the first night under treatment and remained stable three months later, suggesting successful memory integration and restoration of semantic processes. No treatment-related outcome was found on PVT performance. OSA exerts a detrimental but PAP-reversible effect on verbal learning and semantic memory integration mechanisms underlying the acquisition of novel memory representations.

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.