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) epsilon 4 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 epsilon 4 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 epsilon 4 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 epsilon 4 allele and OSA on frontal lobe function in adults, possibly mediated by the presence of specific frontal lobe neuroanatomical changes in these patients. (c) 2007 Elsevier B.V. All rights reserved.