The APOE ε4 allele increases the risk of impaired spatial working memory in obstructive sleep apnea

Background: Contradictory data have been published on the influence of Apolipoprotein E (APOE) ε4 allele on obstructive sleep apnea (OSA). The aims of this study were to confirm the presence of specific neuropsychological changes in OSA patients carrying the APOE ε4 allele and to clarify if these changes are due to the sole presence of this allele or to its interactions with OSA pathology. Methods: The APOE genotype was examined in 123 patients with OSA and in 121 controls, together with a series of neuropsychological tests. Results: OSA and control subjects had similar APOE genotype and allele distribution, but when neuropsychological tests were considered, OSA patients showed significantly lower values for verbal long-term (delayed free recall at the Rey auditory-verbal learning test) and working memory (bisyllabic words). Moreover, spatial span was found to be lower in OSA ε4 allele carriers than in non-carriers; this difference was not observed in controls. Conclusions: This study confirms the presence of a verbal memory impairment in OSA patients and provides evidence for a significant interaction of APOE ε4 allele and OSA on frontal lobe function in adults, possibly mediated by the presence of specific frontal lobe neuroanatomical changes in these patients.