Challenge of a dual burden in rapidly aging Delaware: Comorbid chronic conditions and subjective cognitive decline

Background Epidemiologic trends forecast a “dual burden”- increase in both physical chronic diseases and Alzheimer’s disease (AD)- for Delaware. Estimating the burden and characteristics of this “dual burden” is critical. Cognizant of the unavailability of precise models to measure AD, SCD—a population-based measure- was used as an alternative. The primary objective was to delineate selected chronic conditions among Delaware adults with SCD in order to present: (i) prevalence of SCD by select sociodemographic characteristics, (ii) compare the prevalence of chronic conditions among people with and without SCD, and (iii) compare the prevalence of SCD associated functional limitations in Delawareans with and without comorbid chronic conditions. Methods Combined data (2016 and 2020) for Delaware were obtained from the Behavioral Risk Factor Surveillance System. Analyses included 4,897 respondents aged 45 years or older who answered the SCD screening question as “yes” (n = 430) or “no” (n = 4,467). Descriptive statistics examined sociodemographic characteristics and chronic conditions in Delawareans with and without SCD. Results Overall, 8.4% (CI: 7.4–9.5) of Delaware adults reported SCD. Delawareans with SCD were more likely to be in the younger age group (45–54 years), less educated, low income and living alone. Over 68 percent had not discussed cognitive decline with a health care professional. More than three in four Delawareans with SCD had a 1.5 times higher prevalence of having any one of the nine select chronic conditions as compared to those without SCD. Adults with SCD and at least one comorbid chronic condition were more likely to report SCD-related functional limitations. Conclusions Delaware cannot afford to postpone public policies to address the dual burden of SCD and chronic conditions. Results from this study can help public health stakeholders in Delaware to be informed and prepared for the challenges associated with cognitive decline and comorbidity.

Delaware administered the optional SCD module through BRFSS in 2016 and most recently, in 2020. To the best of our knowledge, no population-based studies have explored and done a detailed characterization of this "dual burden"-SCD and comorbid chronic conditions -in Delaware. This study aims to delineate comorbid chronic conditions among Delaware adults with SCD in order to present: (i) prevalence of SCD by select sociodemographic characteristics including social determinants of health (SDOH) such as education, living alone, income and health care, (ii) compare the prevalence of chronic conditions among people with and without SCD, and (iii) compare the prevalence of SCD associated functional limitations in Delawareans with and without comorbid chronic conditions. It is important to note here that this study findings will come with a caveat. AD is not the only cause of subjective cognitive decline and various other conditions can be associated with subjective memory complaints, such as psychiatric disorders (depression, anxiety) or normal aging. Prior research has revealed an important correlation between SCD and mood disorders (such as depression) [16,17]. It has been argued that subjective decline in cognition reflects affective symptoms (i.e., depression and anxiety) rather than actual cognitive issues.
Living with significant cognitive impairment and co-occurring chronic conditions is an important issue for public health in aging society. Bolstering SCD research efforts will enable improved characterization of this vulnerable Delaware population, support health care and other providers in coordinating and managing care to meet the needs of this fast -increasing demographic. Our hypothesis is that Delawareans with SCD have a significantly stronger association with physical chronic conditions, face more functional limitations and are more vulnerable in terms of the SDOH.

Data source
Behavioral Risk Factor Surveillance System (BRFSS), established in 1984, is the largest random-digit-dialed telephone health survey of noninstitutionalized U.S. adults aged 18 years or older, conducted annually by the Centers for Disease Control and Prevention (CDC) in all 50 states, the District of Columbia, and US territories [18]. In 2015, BRFSS added a six-question optional module on cognitive decline administered to adults 45 years and older. Delaware administered the SCD module in 2016 and 2020.
Combined Delaware BRFSS data for 2016 and 2020 (n = 8,082) were analyzed for this study. 5,641 respondents were aged 45 years or older. In the 45 years or older data set, 4,925 Delawareans responded to the cognitive decline module. Excluding inadequate responses (n = 28), final data set (n = 4,897) included 430 respondents with SCD and 4,467 without SCD (Fig 1). The excluded respondents were similar to those included in the study in terms of age group and race/ ethnicity. Delaware sample was weighted at the state level and analyses conducted with BRFSS specified complex sampling procedures to appropriately stratify and weigh the data [19].
Delaware BRFSS response rates were 47.5% and 44.7% (landline), 38.1% and 35.5% (cell phone) and 43% and 38.5% (combined landline and cell phone) in 2016 and 2020 respectively. Response rates for BRFSS are calculated using standards set by the American Association for Public Opinion Research (AAPOR) Response Rate Formula #4 [20]. The response rate is the number of respondents who completed the survey as a proportion of all eligible and likely-eligible people. For detailed information please see the BRFSS Summary Data Quality Report [21].

Variables
Outcome variable. Subjective cognitive decline. Delawareans who answered "yes" to the question, "During the past 12 months, have you experienced confusion or memory loss that is happening more often or is getting worse?" were included as subjects with SCD. They were then asked four subsequent questions that assessed SCD attributed impairment in activities: (i) how often SCD caused them to give up day-to-day activities such as cooking, cleaning, taking medications, driving, or paying bills; (ii) how often they needed assistance with these day-today activities; (iii) how often were they able to get the help they needed; and (iv) how often did SCD interfere with their ability to work, volunteer, or engage in social activities about the home. Reply as "always, usually, or sometimes" was considered as an affirmation of SCD related functional limitation. In addition, a fifth question asked if they had talked to a healthcare professional about their confusion or memory loss. Independent variables. Data of 4,897 Delawareans were categorized by age group (45-54;55-64 and �65 years), sex (male and female) and race (i) White-Non-Hispanic; ii) Black-Non-Hispanic and iii) Hispanic).
Social determinants of health were characterized by the following variables: 1)educational attainment (did not graduate high school; graduated high school or equivalent; attended college or technical school; and graduated from college or technical school); 2)lives alone or does not live alone; 3) yearly income from all sources (<15,000; 15,000-<25,000;25,000-<35,000; 35,000-<50,000; and � 50,000); and 4) primary health insurance was determined as any kind of health care coverage, including prepaid plans such as health maintenance organizations (HMOs), or government plans such as Medicare, or Indian Health Service or none.
Nine chronic diseases and two health behaviors were assessed for comorbid status with SCD. Participants were identified as having a diagnosed chronic disease if they had been told by a doctor or other health care provider that they ever had (i) angina; (ii) arthritis; (iii) asthma; (iv) cancer (other than skin cancer); (v) chronic kidney disease; (vi) chronic obstructive pulmonary disease; (vii) diabetes (not including gestational, borderline, or prediabetes); (viii) heart attack; and (ix) stroke. Physical exercise was assessed by the following question: "During the past month, other than your regular job, did you participate in any physical activities or exercises such as running, calisthenics, golf, gardening, or walking for exercise?". Delawareans smoking status was assessed as "current", "past" or "never" through a BRFSS calculated variable. Reporting of chronic conditions through BRFSS comes with a limitation. As BRFSS collects information only on conditions confirmed by a doctor or health professional, there is a potential for underreporting of conditions that were undiagnosed or were not recalled by the respondent during the telephone interview.
Delawareans with SCD were compared with Delawareans without SCD for association with selected chronic conditions and SDOH such as education, income, living alone and health care coverage. Prevalence of functional limitations in Delaware adults with SCD was further assessed by comorbid chronic condition status.

Statistical analyses
Disparities amongst Delawareans by SCD status were assessed by calculating weighted estimates accounting for the complex BRFSS sampling methodology. Statistical differences were determined with Rao-Scott chi-square tests. Prevalence ratios (PR) with 95% confidence intervals (CIs) were calculated as unadjusted values. All analyses were performed by using appropriate survey commands in SAS 9.4 (SAS Institute Inc., Cary, NC) was used for all analyses. Statistical significance was denoted by a P value of < .05. As per standard BRFSS data suppression guidelines, if the confidence interval was more than 20 points wide, results for that cell were suppressed. (Table 1) 8.4% (95% CI: 7.4-9.5) of Delawareans aged 45 years or older reported SCD.

Select characteristics of delware adults with SCD
Proportion of females with SCD was higher than males with SCD among Delaware adults. However, differences by gender were not significant (p = 0.2520). SCD prevalence increased with age group being highest in the 65 and older age group, 48.5% (95% CI: 42.1-54.8) although nor statistically significant (p = 0.1126). Across groups defined by race and ethnicity, higher percentages of Delaware adults with SCD were Whites, 78.9% (95%CI: (73.6-84.2) compared to Blacks and Hispanics (p = 0.5515) ( Table 1).
Amongst SDOH, significant differences were observed by educational status and annual income. SCD prevalence was significantly lower among college graduates (p < .0001). Nearly 60% of Delaware adults with SCD had high school or less than high school education.
SCD prevalence was significantly higher among low income groups (p < .0001). Over seventy percent of Delaware adults with SCD annual household income from all sources was less than $50,000 (Table 1).

Comorbid chronic conditions among Delaware adults with SCD (Table 2)
In Delawareans with SCD there was a significantly higher prevalence of all nine selected chronic conditions compared to those without SCD (Table 2). More than three in four Delawareans with SCD had a 1.5 times higher prevalence of having any one of the nine select chronic conditions as compared to those without SCD (p < .0001).

PLOS GLOBAL PUBLIC HEALTH
Dual burden of cognitive decline and chronic conditions Lack of physical activity and smoking were significantly higher among Delawareans with SCD. Adults with SCD were nearly two times less likely to exercise (PR = 1.7, 95% CI: 1.5-2.1) than Delaware adults without SCD. The SCD subgroup of Delaware adults were also more likely to smoke (PR = 1.2, 95% CI: 1.1-1.4).

Functional limitations among DELWARE adults with SCD by chronic condition status (Table 3)
Delaware adults with SCD and at least one comorbid chronic condition were more likely to report SCD-related functional limitations compared to those with SCD and no reported comorbid chronic conditions (p < .0001) ( Table 3).
Less than half (48.7%) of Delaware adults with SCD and at least one comorbid chronic condition reported not discussing their more frequent of worsening confusion or memory loss with a health care professional (p = 0.0102). This percentage was significantly higher than for those without comorbid chronic conditions, where 68.1%(95% CI: 56.2-80.1) of adults did not discuss SCD with a health care professional.
Those with at least one comorbid chronic condition were more likely to report having to always, usually, or sometimes give up household activities because of SCD when compared to those with SCD but with no comorbid chronic conditions (p = 0.033). Nearly four in ten Delawareans with SCD always, usually, or sometimes needed assistance with day-to -day activities due to confusion or memory loss compared to one in four Delawareans without SCD (p = 0.0409).
Greater number (34.8%) of Delaware adults with SCD reported confusion or memory loss (always, usually, or sometimes) to interfere with work or social activities as compared to Delaware adults without SCD (24.7%), although the results were not statistically significant.

Discussion
Nearly one in 12 Delaware adults aged 45 years or older reported SCD. Burden of SCD in Delawareans was further compounded by comorbid chronic conditions. Compared with those without SCD, Delawareans aged 45 years and older with SCD were two or three times more likely to have angina, heart attack, stroke, diabetes, asthma, COPD, cancer, arthritis, or kidney disease. Close to seventy seven percent of Delawareans with SCD have at least one other chronic health condition. This study adds state level presentation of similar national level associations through prior research [9,20,22].
Comorbid chronic conditions can complicate health issues in more than one respect. First and foremost, chronic conditions can increase the risk of cognitive decline and progression to AD [9,20]. Microvascular damage caused by these "cognitive risk factors" can result in a gradual but often more global decline in cognitive function [23]. The second, equally important concern relates to management of comorbid conditions in the presence of SCD. Because of impaired cognitive function, medication instructions or nutritional / physical activity regimes provided by clinicians becomes a challenge. Thus, self-management-a key notion for persons with chronic illness-does not apply to a person with SCD [9,23]. Poorly managed chronic diseases could lead to further cognitive impairment [20,24,25].
Delawareans with SCD were also found to have a significantly higher association with both lack of exercise and smoking tobacco. Study results document smokers are likely to experience faster 10-year cognitive decline in global cognition and executive function [26,27]. Physical activity protects the heart and may also protect the brain and reduce the risk of developing AD [28][29][30]. The 2020 Lancet Commission on dementia prevention clearly recognizes the role of these modifiable risk factors and states that addressing these might prevent or delay up to 40% of dementia cases [31]. In highlighting these associations, this study provides an opportunity for Delaware policy makers to address modifiable risk factors that may delay cognitive decline in Delawareans.
Differences in SDOH-conditions in places where people are born, live, learn, work, and play-can have a profound effect on a person's health, including risk for AD [32]. Study findings demonstrated a significantly higher burden of adverse determinants such as low income and less education. Proportion of Delawareans experiencing SCD was lower among college graduates and those with higher incomes. Researchers believe having more years of education builds up "cognitive reserve (coping ability of the brain to improvise and execute) [32,33].
It is interesting to note that more than fifty percent of Delawareans with SCD were less than 65 years of age. More disturbing was the finding that more than one in four Delawareans with SCD were in the younger age group of 45-54 years. These finding forecasts important health and economic impacts for Delaware. Adults in the age group between 45-54 years are largely considered to be: i) in their heyday of productive work and income, ii) at a time to contribute to maximum to their retirements, and iii) serve as revenue driving consumers [33][34][35]. Delawareans may have to leave workforce entirely due to SCD or reduce work time. In either case there would be dire financial consequences for these adults and their families.
Amongst Delawareans with SCD, more than 60 percent were females. Although not statistically significant, this is a finding of interest. More women-almost two-thirds-than men have AD [9,39]. This difference is most likely attributed to the fact that women live longer than men on average, and older age is the greatest risk factor for AD [40].
Living alone with SCD makes this affected populace more vulnerable [41,42]. Besides an increased risk for injury to self or others there are more unmet needs such as mobility, adherence to medication schedule, activities of daily living and coping with financial matters. In addition, they are less likely to use health services and are at a risk for poor health outcomes [42]. Over thirty percent of Delawareans with SCD were observed to be living alone.
Significant disparities in functional limitations were observed among Delaware adults with SCD. Delaware adults with SCD and at least one comorbid chronic condition were more likely to report SCD-related functional limitations (p < .05). Nearly 4 in 10 of Delawareans with SCD and a chronic condition reported they had to give up day-to-day activities such as cooking, cleaning, or paying bills and needed assistance because of their memory problems. More than 1 in 3 Delaware adults with comorbid SCD and chronic condition say their worsening memory problems interfere with their ability to work, volunteer, or engage socially. Taken together, nearly 73% of Delaware adults with SCD and at least one chronic condition say it creates "functional difficulties"-that is, their memory problems disrupt everyday tasks and/or interfere with work or social activities. Functional limitations increase demand for formal and/ or informal caregiver support and tend to overwhelm available resources [43,44].
Over 68% percent of Delaware adults with SCD (and no comorbid chronic condition) reported not discussing their more frequent of worsening confusion or memory loss with a health care professional. Prior studies have reported up to 54% of those who reported SCD, had not consulted a health care professional [20,22]. Healthy People 2030, a vital framework for prioritizing health issues in U.S. has brought the topic of SCD to the forefront by including a new objective of increasing the proportion of adults with SCD who discuss their confusion or memory loss with a health-care professional over the next decade [45,46]. This encourages states to make SCD a high -priority issue-engage in targeted interventions-and to collect SCD data on an ongoing basis to measure progress [10,46].
Findings in this study are subject to several limitations. First, BRFSS survey samples are collected from noninstitutionalized adults. People living in long-term care facilities and nursing homes may not be included. SCD and chronic conditions prevalence is bound to be higher among older adults living in these facilities. Second, SCD as defined is self-reported, and not an objective assessment. Third, adults with severe cognitive impairment may be limited in their capacity to participate in the survey. Despite these limitations, the BRFSS SCD module is an all-important indispensable tool to provide population-based data and a viable alternative resource to inform public health policy and decision-making on cognitive health issues [10,18]. Consistency of the association between symptoms of depression and SCD has been well documented [47] and indicates that mood symptoms be considered in those who present with SCD. Since this study did not assess correlation of SCD symptoms with mood disorders, it is duly acknowledged to be a limitation. It is to be noted that subjects included in this study come from two rounds (2016 and 2020), with a 4-year period between measurements. However, this was no ordinary gap-the year 2020 saw the most severe stage of the COVID pandemic. It is quite likely that during 2020 the prevalence of depression and mood disorders increased, thus leading to an increased reporting of cognitive impairment.
Another obvious limitation is a fact that this study did not conduct adjusted analyses and the findings are to be interpreted with caution.

Conclusion
Delawareans are living longer than ever before-and that is raising a new challenge that can be taken as an opportunity [9,20]. Considering that by 2030 the proportion of Delawareans over 60 will show a 50.4 percent increase [3], the state cannot afford to postpone public policies to address the dual burden of SCD and chronic conditions. Results from this study can help public health stakeholders in Delaware to be better informed and prepared for the challenges associated with cognitive decline and comorbidity. Delaware's successful initiatives in this regard may well serve as a bellwether, providing a road map for other states.