Nutritional status, macronutrient and micronutrient intake in relation with dementia among older adults in Surabaya, Indonesia: a cross-sectional study

Introduction

Older adults are one of the vulnerable age groups to nutritional problems and are susceptible to various degenerative diseases due to the physiological changes that they experienced. Nutrition related non communicable diseases (NNCDs) that are often experienced by the older adults ranged from hypertension, hypercholesterolemia, gout, osteoporosis to type 2 diabetes mellitus.^1–3 In addition to these various diseases, the older adults are also highly susceptible to dementia. The condition of dementia is often considered a ‘parent’ problem and is not intervened as early as possible. In fact, this condition is degenerative which can have a negative impact on the older adults. According to the World Health Organization (WHO), dementia defined as a symptom of a decrease in memory, thinking, behavior, and the ability to perform daily activities. Early detection of dementia conditions can help in maximizing the utilization of support sources, improving food intake and prompt and appropriate intervention.⁴ Adequate food intake based on their needs is one of the things that must be met to achieve an optimum quality of life. There is no national research data on the prevalence of dementia in Indonesia. However, Indonesia is now experiencing an increase of older adults’ population therefore, many cases of dementia can be found.

Older adults’ population keeps increasing each year both globally and in Indonesia, thus creating more nutrition related problems among them. Globally, 730 million older persons were reported in 2019, with the largest number in Eastern and Southeast Asia; and it is expected to be doubled in the next three decades reaching over 1.5 billion.⁵ Moreover, for the past five decades, the proportion of older adults in Indonesia has approximately doubled (1971–2020) to 9.92 percent (or 26 million), in which there are about one percent more female older adults than male older adults (10.43% compared to 9.42%), and more older adults living in urban compared to rural area (52.95% vs 47.05%, respectively).⁶

The risk factors for dementia are divided into two: modifiable and non-modifiable risk factors. Modifiable risk factors include cardiovascular risk factors including hypertension, hypercholesterolemia, and type 2 diabetes mellitus, intake of folic acid and vitamin B12, lifestyle changes including smoking, drinking alcohol, drinking water, high-fat diet, consumption of vegetables and fruits, consumption of sugar, and physical activity. While the factors that cannot be modified are age, gender, family history and genetic factors.⁷ Older adults are also prone to malnutrition or lack of daily intake due to physiological changes such as sensory impairment and a decline in metabolic rate.⁸ One study in Indonesia reported that the risk of malnutrition among older adults was as high as 59.2%.⁹ As malnutrition risk increases, higher risk to dementia will be also developed. To our knowledge, studies aiming to observe the relationship between nutritional status and daily nutrients intake with dementia among Indonesian older adults are limited. A study in Bogor, Indonesia found that adequacy of vitamin A, vitamin B1, vitamin B2, vitamin B6, and vitamin C intake were correlated to dementia¹⁰ while a study in Yogyakarta, Indonesia found that undernourished older adults were having dementia compared to those with normal nutritional status.¹¹ Based on the above explanations, the authors aim to observe the association between nutritional status, macronutrient and micronutrient intake in relation with dementia among older adults in Surabaya, Indonesia.

Methods

Results

The purpose of our study was to clarify the association between nutritional status, macronutrient, and micronutrient intake in relation with dementia among older adults in Surabaya, Indonesia. The total data collected was 401 samples, but one-missing data was excluded from the analysis. In the end, 400 data was analyzed. We found a quite high proportion of dementia, that is 57% among total samples (32.5% was mild dementia and 24.5% was moderate-severe dementia). Results of older adults’ socio-economic status is presented in Table 1. Based on the mean age, those with dementia were significantly older than those without dementia (69.2 years in mild dementia and 67.7 years in moderate-severe dementia vs 67.5 years in without dementia); which means that the risk of dementia increases with age (p<0.01). In addition, risk of dementia seems to be higher in female than male older adults (p<0.05). Present comorbidities, such as diabetes, hypertension and dyslipidemia (p<0.000), educational background (p<0.001) and monthly income (p<0.01) were shown to be significantly related to dementia; while working status and food expenditure did not show any correlation (p>0.05).

Table 2 presents the analysis of nutritional status and nutrient intakes in relation with dementia status. Based on ANOVA analysis, predictors of dementia were BMI, carbohydrate intake, saturated fat intake, and sodium intake. Other variables such as intake of energy, protein, fat, thiamin, vitamin C, calcium, potassium, iron and zinc did not show any significant difference in older adults with and without dementia (Table 2). The follow-up post-hoc analysis revealed that BMI between moderate-severe dementia was significantly lower than those without dementia (p<0.01).

Carbohydrate intake result showed an average intake of 108.0–127.2 grams/day; the highest carbohydrate intake was found in normal older adults and it significantly differed with mild dementia (p<0.001) as well as moderate-severe dementia (p<0.05). Fiber is one type of carbohydrate that was assessed in our study; there was a difference seen in each pair, but surprisingly, the result was opposite to carbohydrate intake. Older adults with mild dementia showed a higher intake of fiber compared to the normal ones. A similar trend was shown in protein intake, but not fat intake. Protein intake was higher in normal older adults; in contrast, they have lower fat intake, but both did not show a statistically significant result. Mild-dementia older adults significantly outperformed in saturated fat intake and sodium intake compared to the normal older adults (p<0.01).

Discussion

Our study found a high number of dementia proportion. Another study using similar tools, MMSE, to assess dementia also revealed a high dementia prevalence e.g., 77.5%.¹¹ MMSE-based estimations of probable dementia proved as a validated tool for clinical assessments of dementia prevalence in studies that focus on cognitive decline and dementia.¹⁴ Our result was greater than the prevalence in other countries such as China (5.14%)¹⁵; Japan (6.86%)¹⁶; and Yogyakarta, Indonesia (20.4%),¹⁷ although in general, most of the countries report an increase in prevalence throughout the year. Indonesia was counted as the 10^th highest country with dementia worldwide, with 1.2 million older adults based on the 2016 Alzheimer’s Diseases International (ADI) report.¹⁸ A report from a Delphi study concluded that dementia prevalence is higher in developing compared to developed countries,¹⁹ which might be due to differences in exposure to environmental risk factors and higher anemia that has been found to be related to dementia.^20,21

Based on socio-economic status, dementia is significantly higher in older adults, women, people with lower educational backgrounds, people with a lower income and people who have one or more comorbidity. Diabetes is known to be one of the comorbidities that is associated with dementia, although its correlation cannot be specifically explained. A study reported that women with dementia showed lower scores in cognitive function test and in risk of cognitive decline.^22,23 Not only diabetes, metabolic syndrome is marked by higher blood pressure, elevated triglyceride, abdominal obesity, low high-density lipoprotein-cholesterol (HDL-C), and high fasting glucose, which also increases the risk of dementia because metabolic syndrome increases inflammatory markers such as interleukin-6 (IL-6) and C-reactive protein (CRP) which then lead to the cognitive impairment.²⁴

Our study was also in parallel with Fratiglioni,²⁵ a cohort study which included 1,473 subjects which found that there was a higher risk of dementia in women and higher incidence as age increased. A previous study also confirmed that dementia incidence increases dramatically from age 65 to 85 years, specifically, before the age of 64, dementia incidence rates tripled, doubled before the age of 75 for every 5-year rise in age, and then dropped to 1.5 higher risk after 85 years.²⁶ Dementia risk by sex difference was revealed in our study. Azad et al. explains that older women might have a higher risk of dementia due to the decline of estrogen hormones which play roles as the biochemical receptors and neurotransmitter in the brain, also as mild vasodilators that increases blood flow and oxygen to the brain.²⁷ Not only that, higher risk in older women might also be mediated by obesity as a study reported that overweight women are more likely to experience brain tissue loss in the temporal lobe.²⁸ Most of the elders had a monthly income less than IDR500,000 or equal to USD35 based on the interview, those who still have income mostly came from working, pension money or from their children. However, in general, their monthly income was still far beyond the minimum regional wage. The lower the income, the higher the risk of food insecurity that could affect daily intake. As for educational background, most of the older adults had <6 years of education and this study proved that lower education means a higher risk of dementia.

Educational level and dementia showed a negative correlation, which means that the lower the education level, the higher the risk of dementia among older adults. This was in line with a meta-analysis that confirmed that the magnitude of risk ranged from 1.4–1.79 for low education,²⁹ and a systematic review that found a lower education was associated with a greater risk of dementia.³⁰ It has been discussed that years of education reflected cognitive capacity, and those with lower education might present lower cognitive capacity then resulting in a greater risk of dementia. Education also affects adult socio-economic status that linked to factors like work and toxin exposure, as well as habits such as nutrition, exercise, and lifestyle. In this model, schooling had no direct impact on dementia risk, but it does influence a variety of factors over the lifespan.³⁰ The monthly income of older adults also showed a negative correlation, which meant that the lower the income, the higher the risk of dementia appears. Similar to educational level, monthly income might not directly affect dementia, but it first influences the daily intake of older adults or their food security level.

Our study result was in line with a retrospective cohort study showing that risk of dementia increased by 34% in those with a lower BMI (<20 kg/m²)³¹; and it is contradictive with previous studies showing that obesity increased dementia risk, so the correlation between BMI and dementia remains unclear. A newly published meta-analysis describes that, in later-life, being underweight might be mediated by the presence of comorbidities that lead to the weight loss,³² which is also seen in our study. Furthermore, predementia apathy causes decreased olfactory function, eating difficulties, or inadequate nutrition that led to weight loss; this also explains why those with dementia present a lower BMI.^33,34 Another study revealed a U-shape relationship between BMI and dementia, where both under and overweight were correlated to dementia.³⁵

Another interesting result of this study is that carbohydrate and protein intake were higher in the without dementia group except for fiber and fat, which was higher among older adults with dementia. It is emphasized that macronutrient distribution is more important than just focusing on only energy intake. The quality of the carbohydrate is also important compared to total intake; we hypothesizethat older adults without dementia consumed more carbohydrates that are higher in fiber content, while those with dementia consume less fiber, but more refined carbohydrates, thus, increasing the risk of dementia.^36,37 Saturated fat and sodium are known as nutrients that cause many negative impacts. In relation to dementia, a higher intake of saturated fats induces oxidative-stress, as reported by Tabet, et al. that dementia patients showed a significantly higher blood glutathione peroxidase activity.³⁸ In addition, a study proposed that high saturated fats also altered sphingolipid and cholesterol metabolism then causes neurodegeneration.³⁹ One possible mechanism link between saturated or trans fat intake to dementia risk is that both types of fat tend to elevate plasma total and low-density lipoprotein cholesterol (LDL-Cl) concentrations which, in turn, may be associated with dementia. Puglielli, et al.⁴⁰ explains that abnormal accumulation of amyloid β-peptide (Aβ) could pathogenically lead to Alzheimer’s disease. Cholesterol overload increases Aβ secretion, thus maintaining cholesterol level among older adults’ is crucial. Fiocco et al. in their 3-year cohort study also found that sodium intake was associated with a higher MMSE score.⁴¹ Those associations were explained via blood pressure elevation, which then associated with white matter lesions that causes cognitive declines.^42,43 Research studies found that a high intake of salt could increase the risk of dementia and cognitive impairment by influencing systemic and cerebral blood vessels.^44,45 Animal’s study also found that high intake of salt increased amyloid or neurotoxicity which lead to cognitive decline.⁴⁶

We note some limitations in our study, first is that the use of cross-sectional study so we cannot infer a causality between variables tested. Therefore, future studies with longitudinal designs to clarify these associations need to be conducted. Second, calculation of micronutrient intake was based on Indonesian Food Database available at Nutrisurvey software. Some food items in the Indonesia food database lacked micronutrient content, thus, this might cause the results of micronutrient intake to have been underestimated. Despite its limitations, this preliminary study can be beneficial to develop promotional action and intervention to prevent dementia considering limited research is available, especially in Indonesia. In conclusion, this study revealed a significant relationship between age, sex, presence of comorbidities, educational level, monthly income, BMI, carbohydrate, saturated fat and sodium intake with dementia among older adults.

Conclusion

In summary, our data reveals a high prevalence of dementia in the study population and a significant association between BMI, especially between not dementia and mild-severe dementia, also correlation of carbohydrate, saturated fat, sodium intake and dementia among older adults aged ≥65 years. This study offers an important insight to improve older adults’ daily intake and nutritional status intake in minimizing the risk of dementia and emphasizes a balanced-diet lifestyle during older adults’ period. Due to the high prevalence and many health consequences, government in public health sectors should put older adults’ health issue including dementia.