COPD with Cognitive Status in an Elderly Sample

COPD with cognitive Status in an Elderly SampleCOPD with Cognitive Status in an Elderly Sample using the Third National Health and Nutrition Examination SurveyDean Sherzai, MD MAS PhD(c), Rachel Schade, Sonia Vega, Ayesha Z. Sherzai, MDAuthors Affiliations 1Department of clinical neurology and Neurological Sciences, Cedar Sinai Health System, Los Angeles, CA, USA 2Keck Science Department, Pitzer College, Claremont, CA, USA 3Department of Epidemiology and Biostatistics, Loma Linda School of Public Health, Loma Linda, USA Department of Neurology, The Neurological Institute of New York, Columbia University checkup Center, New York, New York, USA.Keywords COPD, cognitive posture, delirium, agingAbstractPurpose Chronic obstructive pneumonic indisposition (COPD) has been associated with dementia and cognitive impairment. We attempted to assess the family betwixt COPD and cognitive impairment in a nationwide database, the National Health and Nutrition Examination Survey (NHANES ter cet).Methods Data was analyzed from the NHANES III database, a nationally representative cross sectional observational study among older pornographics. The diagnosis of COPD was ground on calculation of FEV1/FVC ratio, with a cutoff of 0.7. The odds of having ugly cognitive status was assessed using logistic regression models between COPD and three cognitive tests ( immediate recall, delayed recall, and straight subtraction tests), adjusted for demographic variables and medical comorbidities.Results We set 17,181,182 individuals with a diagnosis of COPD. The mean age of was 71.5 0.19 years. In the crude model, there was a strong blood between those with COPD and poor cognitive test scores. This relationship was strengthened in the multivariate model adjusted for demographic variables and vascular comorbidities, such that those with COPD had a higher odds of having impaired immediate recall (OR 2.56, 95% CI 1.44- 4.53), delayed recall (OR 3.10, 95% CI 1.73- 5.52), and serial s ubtraction tests scores (OR 2.74, 95% CI 1.17- 6.40).Conclusions Individuals with COPD have a higher odds of having cognitive impairment in this large nationally representative database.IntroductionApproximately 35.6 million currently suffer from dementia worldwide, and this number is expected to double by 2030 and triple by 2050 1. In the last few years we have become more cognizant of the importance of identifying cognitive decline at the preliminary stages when it is more amenable to treatment. We have also become more knowledgeable ab step up possible comorbidities that may propagate the process of cognitive decline and last dementia.Causes of cognitive decline, and possible progression to dementia, are believed to be multifactorial. Chronic Obstructive Pulmonary Disease (COPD) is a progressive illness that affects more than 13.5 million good deal in the United States and has been associated with cognitive decline 2. To date, there are no definitive treatments for dementia t he readerore, much emphasis had been placed on the prevention of dementia, and identification of modifiable attempt factors early in the disease process. Multiple studies have reported the draw between COPD and either global cognitive deficits with the most difficult deficiencies in specific cognitive domains such as perception, motor function or memory 3. Despite the current body of evidence, the majority of studies are based on a single region, and there are a few studies that utilise a nationally representative data (Health and Retirement Study). Given that rules of order is facing an increase in the rate of chronic diseases of aging 4, and the lack of large scale investigation on the relationship between COPD and diminished cognitive status, we analyzed this nationwide database, the National Health and Nutrition Examination Survey (NHANES III), to better elucidate this relationship.Materials and MethodsNHANES III is a cross sectional wellness flock conducted by the Nation al Center for Health Statistics (NCHS), performed from 1988 to 1994 in persons aged two months and older in the United States. NHANES has a multistage, probability sampling design used to select participants representative of the civilian, non-institutionalized US population. Our study population consisted of 39,488,973 adults 60 to 89 years. Of these, participants were included if they had measurements for spirometry and the cognitive tests. Based on The Global Initiative for Chronic Obstructive Pulmonary Disease (GOLD) standards, cases of COPD were defined based on the patients ratio of forced expiratory volume (FEV1) to the forced vital capacity (FVC). Patients with a ratio of slight than 0.7 were classified with COPD. Our control group, patients with unwrap COPD, was classified by a ratio greater than 0.7. For the older population, NHANES-III measures cognitive status with three cognitive tests an immediate and delayed logical communicatory memory test from the East Boston Mem ory Test, a three word registration/memory task (apple, evade and penny) and five serial subtractions by intervals of three. A point was awarded for every correct answer from the three word memory task and the logical verbal memory test. For immediate memory, using a summary score of logical memory (0-6 points) plus three word task (0-3 points), we considered less than 5 out of 9 points to be impaired (low), such that individuals with 0-4 were score low, and those scoring 5-9 were scored high. For delayed memory, a summary score of less than 4 out of 9 points was considered impaired (low). Both summary scores are consistent with previous NHANES-III reports. For the test of serial subtractions, any miscalculation during the five trials was considered impaired, and only a perfect score was considered high.The reported race and ethnicity includes non-Hispanic Whites, non-Hispanic Blacks, Mexican-Americans and other. Smoking was defined by a yes response to the following two questions Have you smoke at least 100 cigarettes during your entire life and Do you smoke cigarettes now. These questions can be found on the NHANES III household adult questionnaire. Education was stratified in three categories 12 (some college and beyond).We performed an X2 and t-test analysis to compare demographic characteristics between patients with COPD and patients without COPD. To assess the association between COPD and a low cognitive test score (with high score as reference) crude and adjusted logistic regression analysis were performed. Adjusted potential confounders were age, race-ethnicity, sex, BMI, education status and smoking. confiscate NHANES-III weighted sampling was applied during this analysis. All data analyses were conducted using SAS (v 9.3 SAS Institute Inc., Cary, NC).ResultsTable 1 presents the demographics of the population. There were 17,181,182 individuals with COPD 50.1% were females, 49.9% males and 85.9% were non-Hispanic White. The mean age for patients w ith COPD was 71.50.19. In both groups, patients had less than a high school education, were non-smokers and had both hospital and medical coverage. Majority of individuals with COPD scored low on each cognitive test as compared to those without COPD (Table 1). Coronary arterial blood vessel disease was the most prevalent comorbidity in patients with COPD (31.9%) and in patients without COPD (30.4%).In the unadjusted model, participants with COPD had increased odds of impaired scores on each of the three cognitive tests the immediate recall (OR 2.18, 95% CI 1.81- 2.62), delayed recall (OR 2.25, 95% CI 1.87- 2.70) and serial subtraction test (OR 1.44, 95% CI 1.10-1.90).We then examined the association between COPD and the cognitive tests, initially adjusted by age and race, which diminished the relationship slightly for all three tests, but the relationship was rendered insignificant for the serial subtraction test (OR 1.29, 95% CI 0.95-1.69) (Table 2). Then, we adjusted for age, sex, height, body mass index and education, which did non change the relationship significantly. In the third model, further enrollment for race, poverty income ratio, and medical coverage did non appreciably change the relationship. In the last model, we to boot adjusted for vascular risk factors such as smoking, stroke, hypertension, CHF, diabetes and coronary artery disease. This increased the odds for poor scores for all three tests immediate recall (OR 2.56, 95% CI 1.44- 4.53), delayed recall test (OR 3.10, 95% CI 1.73- 5.52), and serial subtraction (OR 2.74, 95% CI 1.17- 6.40).DiscussionWe were able to identify a strong association between COPD and diminished cognitive status across three common cognitive tests. Individuals with COPD had significantly greater odds of impaired verbal memory, and this relationship remained robust after adjusting for potential sociodemographic and vascular risk factors. The relationship between COPD and the serial subtraction test scores was rende red significant after it was adjusted for vascular risk factors. Despite evidence in the existing literature showing an association between race with cognitive status 10, race was not a factor in the relationship between COPD and cognitive status.Our results are consistent with a growing body of evidence that has revealed a strong association between COPD and poor cognitive function. In unmatchable of the largest epidemiologic studies, The Health and Retirement Study (n=4,150), patients with severe and non-severe COPD had significantly turn down cognitive test scores compared to healthy controls. In adjusted models, only patients with severe COPD had the lower scores on the cognitive tests 5. advancemore, a dose-response relationship between COPD severity and cognitive dysfunction was previously established, with more severe COPD cases performing worse on the cognitive tests 6. Notably, a 2013 study manifest significantly reduced memory tests scores on the Mini Mental State Ex am (MMSE) among patients with COPD but without hypoxemia 7. Further evidentiary support for global cognitive impairment in patients with COPD was also shown in a study that observed significant differences in executive functioning, work memory, episodic memory, processing speed, and visuospatial ability 8. Recently, several COPD studies have combined cognitive testing with neuro tomography, which have revealed significant white matter pathology in this population, with varying degrees of cognitive impairment 8,9,10,11.The mechanism by which COPD causes cognitive decline is not very clear. COPD results in hypoxemia and hypercapnia, which has been implicated in diminished cognitive status 3,5. Recent imaging studies have pointed to possible microvascular damage 3, and other studies have implicated chronic inflammatory process causing cognitive decline 12. Yet others believe that the hypoxic process may cause direct neuronal damage, glial activation and the generation of free radicals which could affect cognitive functioning 13. Given the prevalence of both COPD and cognitive decline in the elderly population and a probable causal relationship, it is important to further investigate the mechanism underlying the relationship.LimitationsAs all studies, this one has many limitations that need to be visited. One of the limitations unique to our study was that majority of the individuals in our elderly NHANES population had less than high school education. Given that educations has repeatedly been found to be strongly correlated with resilient cognitive function as well as less susceptible to neurodegeneration, our results could have been confounded by the lower mean education level in our population14-18. Another limitation lies with the cognitive testing used by NHANES. Only three cognitive tests were utilized, which does not provide a comprehensive assessment of cognitive function. In addition, the cognitive tests used most likely overlap in the cognitive function they measure, not allowing for specificity. However, the cognitive variables have been validated as a good tool for testing memory 19. Furthermore, the cross-sectional nature of this paper does not allow us to make a causal link. In addition, the restricted scope of lifelong socioeconomic status is a limitation, which is strongly associated with both cognitive impairment and COPD. However, it has been demonstrated that individuals with poor socioeconomic status may have a higher risk of developing COPD and lower cognitive reserve 20,21. The strengths of this study are its large, different representative sample, that provided extensive medical history and allowed for control of confounding variables, as well as the objective measure of cognitive impairment and COPD. Also, the spirometry data from NHANES III allowed for more accurate diagnosis of COPD.ConclusionWe were able to demonstrate a strong relationship between COPD and diminished cognitive status. 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Ann Neurol 199537(5)590-595.Table 1. service line characteristics by COPD status in the NHANES III population* p values derived from t test comparison of means of COPD by population characteristicsS D = Standard varianceTable 2 Crude and adjusted odds ratio for COPD and cognitive tests among 17,134,886 individuals in the NHANES III populationOR = odds ratio, CI = confidence interval, ref = referenceModel 1 adjusted for age and raceModel 2 adjusted for age, sex, height, BMI and educationModel 3 Model 2 additionally controlled for poverty income ratio, race, and medical coverageModel 4 Model 3 additionally adjusted for stroke, coronary heart disease, hypertension, congestive heart failure, diabetes.1