Individuals with Overlap Syndrome have Lower Cognitive Performance than Individuals with COPD or Obstructive Sleep Apnea Alone: Role of Carotid Artery Stiffness

Abstract

BackgroundChronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA) are two of the most prevalent respiratory disorders in adults and are both independently associated with impaired cognitive function. The coexistence of OSA in individuals with COPD is termed ‘overlap syndrome’ and occurs in up to 65% of all COPD patients. However, it is unknown if individuals with overlap syndrome have lower cognitive function than individuals with COPD or OSA alone. Carotid artery stiffness is associated with cognitive dysfunction among individuals with and without known cardiovascular disease (CVD). Both COPD and OSA are independently associated with greater carotid artery stiffness compared with controls. It is not known if carotid artery stiffness is exacerbated in overlap syndrome patients and if greater carotid artery stiffness is associated with lower cognitive function in this group. We hypothesized that a) individuals with overlap syndrome would have reduced cognitive performance and greater carotid artery stiffness than individuals with either COPD or OSA alone and b) greater carotid artery stiffness would be associated with reduced cognitive performance among individuals with overlap syndrome.MethodsNinety former smokers (n=12 with overlap syndrome, n= 45 with COPD only, n= 12 with OSA only and n=21 controls; age 69 ± 7 yrs; 53M/37F) completed measurements of pulmonary function, common carotid artery stiffness and neuropsychological testing. OSA status was determined by self‐report of previous clinical diagnosis with OSA.ResultsIndividuals with overlap syndrome performed lower in the executive functioning domain after adjusting for age, sex, body mass index (BMI) and FEV1/FVC than individuals in the other groups (overlap 43.5 ± 4.8 vs. COPD 48.3 ± 5.1 vs. OSA 51.8 ± 5.2 vs. controls 50.2 ± 5.4 norm‐based age‐adjusted t‐scores; P=0.019). Individuals with overlap syndrome also had greater carotid β‐stiffness index compared with individuals in the other groups after adjusting for age, BMI, sex and FEV1/FVC (overlap 5.9 ± 2.5 vs. COPD 3.92 ± 1.4 vs. OSA 3.5 ± 1.1 vs. controls 3.5 ± 1.1U; P=0.015). There were no differences in blood pressure, heart rate, resting oxygen saturation (SpO2) or nocturnal mean SpO2 in overlap syndrome patients vs. the other groups. Higher carotid β‐stiffness index was associated with lower executive function performance in the entire cohort (r=−0.32, P=0.002) and in individuals with overlap syndrome (r=−0.58, P = 0.048). There was no relation between carotid β‐stiffness index and executive function in individuals with COPD alone, OSA alone or former smoker controls (all P>0.05).ConclusionThese data suggest that cognitive performance is lower in individuals with overlap syndrome than in individuals with either COPD or OSA alone and that exacerbated carotid artery stiffening may be an underlying mechanism for the lower cognitive performance observed in this group.Support or Funding InformationNIH K23 HL095658; R01 HL089897 NIH/NCATS Colorado CTSI; UL1 TR001082This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.