Original article Effects of obstructive sleep apnea on cognitive function: A comparison between younger and older OSAS patients A. Mathieu a,b , S. Mazza a , A. De ´cary a,c , J. Massicotte-Marquez a,d , D. Petit a , N. Gosselin a,d , J. Malo e , J. Montplaisir a,c, * a Centre d’e ´ tude du sommeil et des rythmes biologiques, Ho ˆ pital du Sacre ´ -Coeur de Montre ´ al, 5400 boul. Gouin Ouest, Montre ´ al, Que., Canada H4J 1C5 b Department of Medical Bioscience, Universite ´ de Montre ´al, Canada c Department of Psychiatry, Universite ´ de Montre ´al, Canada d Department of Psychology, Universite ´ de Montre ´al, Canada e Service de pneumologie, Ho ˆpital du Sacre ´-Coeur de Montre ´al, 5400 boul. Gouin Ouest, Montre ´al, Que., Canada H4J 1C5 Received 3 November 2006; received in revised form 28 February 2007; accepted 8 March 2007 Available online 21 May 2007 Abstract Background and purpose: Patients with obstructive sleep apnea syndrome (OSAS) present cognitive deficits similar to those observed with aging. The aim of the study was to assess the effects of age on cognitive functions in OSAS patients. It was hypothesized that older OSAS patients will exhibit significant cognitive dysfunction relative to younger OSAS patients and controls. Patients and methods: Younger and older OSAS patients were compared to younger and older control subjects (age cut-off set at 50 yrs). Participants underwent a polysomnographic (PSG) and neuropsychological evaluation. Variables were analyzed by two-way analyses of variance (ANOVAs) with two factors: Group (control and OSAS) and Age (younger and older). Additionally, we eval- uated the contribution of attentional deficits to cognitive dysfunction for each subgroup of patients by using Spearman correlation coefficients. Results: No Group-by-Age interaction was found for any neuropsychological variables (p < 0.05). However, main Group and Age effects were found. Correlations indicated that attentional deficits contributed importantly to a poorer cognitive performance in younger OSAS patients only (p < 0.01). Conclusions: Our results are in agreement with those of the literature for both OSAS-related and aging-related cognitive deficits but did not demonstrate that age interacts with the effects of the OSAS condition to make those cognitive deficits worse. Ó 2007 Elsevier B.V. All rights reserved. Keywords: Age; Sleep apnea; Cognitive function; Daytime vigilance; Elderly 1. Introduction Obstructive sleep apnea syndrome (OSAS) is charac- terized by a perturbation of the pharyngeal dilator mus- cles, which causes frequent cessations of breathing (apneas) accompanied by a reduction in ventilation (hypopneas) during sleep. Electroencephalographic (EEG) arousals and oxygen desaturation are immediate consequences of these respiratory events. In adults, untreated OSAS results in excessive daytime sleepiness (EDS) [1], cognitive dysfunction [2,3], cardiovascular diseases and brain damage [4]. Epidemiological studies indicate that OSAS associated with abnormal sleepiness is a prevalent sleep problem, affecting 4% of men and 2% of women [5]. Neuropsychological studies of OSAS patients showed deficits in cognitive domains related to the prefrontal cortex, such as executive functions [6,7] and working memory [6,8,9]. Other cognitive 1389-9457/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.sleep.2007.03.014 * Corresponding author. Tel.: +1 514 338 2693; fax: +1 514 338 2531. E-mail address: jy.montplaisir@umontreal.ca (J. Montplaisir). www.elsevier.com/locate/sleep Sleep Medicine 9 (2008) 112–120