Dementia risk by combinations of metabolic diseases and body mass index: Japan Gerontological Evaluation Study Cohort Study

Reduction in the incidence of cognitive impairment and related costs through an innovative health awareness programme in rural Japan

OBJECTIVES

This study examined the impact of the Center of Healthy Aging Program (CHAP) on the cognitive function and economic burden associated with dementia.

METHODS

This observational study utilised Iwaki cohort data. We included participants with mini-mental state examination (MMSE) scores and categorised them into pre- and post-CHAP groups based on their year of entry into the cohort (before 2013 or after) (index year). We defined participants with suspected severe cognitive impairment and suspected mild cognitive impairment using their MMSE scores, with their incidence being the first observation meeting these definitions during the follow-up period. We compared the incidence rates between the pre- and post-CHAP groups using Cox proportional hazard analysis. Medical and caregiving costs were estimated based on the projected number of residents in Iwaki area with suspected mild cognitive impairment and sSCI during hypothetical 10 years of the CHAP implemented or not and compared.

RESULTS

Of the 2,569 participants, 1716 and 853 were included in the pre- and post-CHAP groups, respectively. The incidence rate of suspected mild cognitive impairment was significantly lower in the post-CHAP group even after adjusted known factors associated with cognitive disorders. No cases of suspected severe cognitive impairment occurred in the post-CHAP group during the follow-up period. Estimated costs of JPY 1,628,450 (USD 11562.00 or EUR 10259.24, JPY 100  =  USD 0.71 or EUR 0.63) and JPY 789,560 (USD 5605.88 or EUR 4974.23) per person per year were projected after 10 years with and without the CHAP, respectively.

CONCLUSIONS

We demonstrated a reduction in the incidence rate of suspected mild cognitive impairment among residents who participated in the CHAP and a decrease in the medical and caregiving costs associated with suspected severe cognitive impairment.

Utilization of Japanese long-term care-related data including Kaigo-DB: An analysis of current trends and future directions

Despite high expectations from the government and researchers regarding data utilization, comprehensive analysis of long-term care (LTC)-related data use has been limited. This study reviewed the use of LTC-related data, including Kaigo-DB, in Japan after 2020. There was an increase in studies using LTC-related data in Japan between 2020 and 2021, followed by a stabilization period. The national government provided 13.5% of this data (6.5% from Kaigo-DB), while prefectures and municipalities contributed 85.2%, and facilities provided 1.3%. The linked data used in 90.4% of the studies primarily consisted of original questionnaire or interview surveys (34.6%) and medical claims (34.0%). None of the studies based on Kaigo-DB utilized linked data. In terms of study design, cohort studies were the most common (84.6%), followed by descriptive (5.1%), cross-sectional (3.2%), and case-control studies (1.3%). Among the 138 individual-based analytical descriptive studies, the most frequently used LTC-related data as an exposure was LTC services (26.8%), and the most common data used as an outcome was LTC certification or care need level (43.5%), followed by the independence degree of daily living for the older adults with dementia (18.1%). To enhance the use of LTC-related data, especially the valuable national Kaigo-DB, insights can be gleaned from how researchers effectively utilize municipal and prefectural data. Streamlining access to Kaigo-DB and enabling its linkage with other datasets are promising for future research in this field.

The Role of Body Mass Index, Advanced Age, and Low Educational Attainment in Mild Cognitive Impairment among the Older Adult Population: A Study in a Rural Area in Indonesia

This study evaluated the prevalence of mild cognitive impairment (MCI) and factors associated with MCI among older adults in a rural area of Indonesia. This cross-sectional study was conducted in a rural area of East Java, Indonesia. Four hundred and twenty-seven older adults aged ≥60 years were included in the study. MCI was assessed using the Brain Health Test Cognitive Tool. Data related to possible risk factors were obtained using semi-structured questionnaires. The indirect body mass index was determined based on ulnar length. The prevalence of MCI was 12.9%. Being underweight (<18.5 kg/m2) (odds ratio [OR], 2.42; 95% confidence interval [CI], 1.17-4.97; p = 0.016), requiring assistance to manage money or medications (OR, 2.72; 95% CI, 1.02-7.23; p = 0.045), age ≥70 years (OR, 2.50; 95% CI, 1.11-5.60; p = 0.026), and having an educational attainment of ≤6 years (OR, 4.92; 95% CI, 1.92-12.60; p = 0.001) were significantly associated with MCI. In this Indonesian older adult population, underweight people who had an educational attainment of <6 years, those aged ≥70 years, and those who needed assistance to manage money or medications were more likely to have MCI.

CKD, Brain Atrophy, and White Matter Lesion Volume: The Japan Prospective Studies Collaboration for Aging and Dementia

Rationale & Objective

Chronic kidney disease, defined by albuminuria and/or reduced estimated glomerular filtration rate (eGFR), has been reported to be associated with brain atrophy and/or higher white matter lesion volume (WMLV), but there are few large-scale population-based studies assessing this issue. This study aimed to examine the associations between the urinary albumin-creatinine ratio (UACR) and eGFR levels and brain atrophy and WMLV in a large-scale community-dwelling older population of Japanese.

Study Design

Population-based cross-sectional study.

Setting & Participants

A total of 8,630 dementia-free community-dwelling Japanese aged greater than or equal to 65 years underwent brain magnetic resonance imaging scanning and screening examination of health status in 2016-2018.

Exposures

UACR and eGFR levels.

Outcomes

The total brain volume (TBV)-to-intracranial volume (ICV) ratio (TBV/ICV), the regional brain volume-to-TBV ratio, and the WMLV-to-ICV ratio (WMLV/ICV).

Analytical Approach

The associations of UACR and eGFR levels with the TBV/ICV, the regional brain volume-to-TBV ratio, and the WMLV/ICV were assessed by using an analysis of covariance.

Results

Higher UACR levels were significantly associated with lower TBV/ICV and higher geometric mean values of the WMLV/ICV (P for trend = 0.009 and <0.001, respectively). Lower eGFR levels were significantly associated with lower TBV/ICV, but not clearly associated with WMLV/ICV. In addition, higher UACR levels, but not lower eGFR, were significantly associated with lower temporal cortex volume-to-TBV ratio and lower hippocampal volume-to-TBV ratio.

Limitations

Cross-sectional study, misclassification of UACR or eGFR levels, generalizability to other ethnicities and younger populations, and residual confounding factors.

Conclusions

The present study demonstrated that higher UACR was associated with brain atrophy, especially in the temporal cortex and hippocampus, and with increased WMLV. These findings suggest that chronic kidney disease is involved in the progression of morphologic brain changes associated with cognitive impairment.

Decreased circulating branched-chain amino acids are associated with development of Alzheimer's disease in elderly individuals with mild cognitive impairment

Background

Nutritional epidemiology has shown that inadequate dietary protein intake is associated with poor brain function in the elderly population. The plasma free amino acid (PFAA) profile reflects nutritional status and may have the potential to predict future changes in cognitive function. Here, we report the results of a 2-year interim analysis of a 3-year longitudinal study following mild cognitive impairment (MCI) participants.

Method

In a multicenter prospective cohort design, MCI participants were recruited, and fasting plasma samples were collected. Based on clinical assessment of cognitive function up to 2 years after blood collection, MCI participants were divided into two groups: remained with MCI or reverted to cognitively normal ("MCI-stable," N = 87) and converted to Alzheimer's disease (AD) ("AD-convert," N = 68). The baseline PFAA profile was compared between the two groups. Stratified analysis based on apolipoprotein E ε4 (APOE ε4) allele possession was also conducted.

Results

Plasma concentrations of all nine essential amino acids (EAAs) were lower in the AD-convert group. Among EAAs, three branched-chain amino acids (BCAAs), valine, leucine and isoleucine, and histidine (His) exhibited significant differences even in the logistic regression model adjusted for potential confounding factors such as age, sex, body mass index (BMI), and APOE ε4 possession (p < 0.05). In the stratified analysis, differences in plasma concentrations of these four EAAs were more pronounced in the APOE ε4-negative group.

Conclusion

The PFAA profile, especially decreases in BCAAs and His, is associated with development of AD in MCI participants, and the difference was larger in the APOE ε4-negative population, suggesting that the PFAA profile is an independent risk indicator for AD development. Measuring the PFAA profile may have importance in assessing the risk of AD conversion in the MCI population, possibly reflecting nutritional status.

Clinical trial registration

[https://center6.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000025322], identifier [UMIN000021965].

Sex-Differential Associations Between Body Mass Index and the Incidence of Dementia

BACKGROUND

Little is known about the sex differences in the association between body mass index (BMI) and dementia in late life.

OBJECTIVE

Therefore, this retrospective cohort study aimed to analyze associations between BMI and dementia in older women and men separately in general practices in Germany.

METHODS

This study included patients followed in one of 832 general practices in Germany between 2006 and 2019 (index date: first visit date). Study variables included dementia (dependent variable), BMI (independent variable), age, sex, and comorbidities (control variables). Kaplan-Meier curves and adjusted Cox regression analyses were conducted to analyze associations between BMI and the 10-year incidence of dementia in women and men, separately.

RESULTS

There were 296,767 patients included in this study (mean [standard deviation] age 70.2 [5.9] years; 54.3% women). The proportion of underweight, normal weight, overweight, and obesity was 0.9%, 25.5%, 41.5%, and 32.1%, respectively. The 10-year incidence of dementia significantly decreased with increasing BMI, from 11.5% in women with underweight to 9.1% in those with obesity (log-rank p <  0.001). Respective figures in men were 12.0% and 8.2% (log-rank p <  0.001). In women, only overweight (versus normal weight) was significantly associated with dementia (HR = 0.93, 95% CI = 0.88-0.97). In contrast, in men, the only BMI category significantly associated with the incidence of dementia was underweight (HR = 1.58, 95% CI = 1.11-2.25).

CONCLUSION

In this study conducted in Germany, overweight was negatively associated with dementia in women, whereas there was a positive underweight-dementia relationship in men. More data are needed to confirm or refute these findings in other settings.

Association Between Body Mass Index and Incident Dementia Among Community-Dwelling Older Adults: The Shanghai Aging Study

BACKGROUND

The relationship between body mass index (BMI) and dementia is inconclusive. Undesirable loss of fat-free mass is a risk factor for cognitive decline while obesity is also a risk factor for cardio-metabolic disorders among the older adults.

OBJECTIVE

This study aimed to examine the association between BMI and incident all-cause dementia among Chinese older adults using a prospective study.

METHODS

Participants were 1,627 community residents aged 60 or older without dementia from the Shanghai Aging Study. Cox regression models, incorporated with restricted cubic splines, were used to explore a nonlinear association between baseline BMI and risk of all-cause dementia as measured by hazard ratio (HR) using both frequentist and Bayesian approach.

RESULTS

We diagnosed 136 incident dementia cases during the mean follow-up of 5.3 years. Compared with moderate BMI (18.5-24.0 kg/m2), low BMI (<  18.5 kg/m2) were related to an increased risk of dementia with the HR as 3.38 (95% CI 1.50-7.63), while high BMI (≥24.0 kg/m2) showed a decreased risk of dementia without statistical significance (HR = 0.91, 95% CI 0.60 to 1.39). Sensitivity analysis in participants without central obesity indicated that the association was still significant with even higher HR. Bayesian approach presented the similar results.

CONCLUSION

Our result indicates that low BMI may contribute to high risk of incident dementia, even in individuals without central obesity.

The Lifelong Health Support 10: a Japanese prescription for a long and healthy life

BACKGROUND

Although the age-adjusted incidence and mortality of cancer and cardiovascular disease (CVD) have been decreasing steadily in Japan, both diseases remain major contributors to morbidity and mortality along with the aging society. Herein, we aim to provide a prescription of 10 health tips for long and healthy life named the "Lifelong Health Support 10 (LHS10)."

METHOD

The LHS10 was developed by the preventive medicine specialists at the National Cerebral and Cardiovascular Center in Suita, where it has been used for health guidance to prevent CVD, cancer, and cognitive decline in addition to their major risk factors such as hypertension, diabetes, and obesity. It consisted of the lifestyle modification recommendations of the 2014 Japanese Society of Hypertension guidelines and the 2017 Japan Atherosclerosis Society Guidelines for preventing atherosclerotic CVD. Further, it came in line with other international lifestyle modification guidelines. In this narrative review, we summarized the results of several Japanese epidemiological studies investigating the association between the LHS10 items and the risk of cancer, CVD, and other chronic diseases including dementia, diabetes, and chronic kidney disease.

RESULTS

The LHS10 included avoiding smoking and secondhand smoke exposure, engaging in physical activity, refraining from excessive alcohol drinking, reducing fried foods and sugary soft drinks, cutting salt in food, consuming more vegetables, fruits, fish, soy foods, and fibers, and maintaining proper body weight. All items of the LHS10 were shown to reduce the risk of cancer, CVD, and other chronic diseases.

CONCLUSIONS

The LHS10 can be a helpful tool for health guidance.

Association between Visceral Fat and Brain Structural Changes or Cognitive Function

Visceral fat accumulation is an independent risk factor for cardiovascular disease and mortality. Visceral fat is a causal risk factor for hypertension and type 2 diabetes, which was reported as one of the risk factors for dementia. Visceral fat areas (VFA) might be clinically important to prevent dementia; however, the association between VFA and cognitive function in the elderly remains unknown. We aimed to evaluate the association between brain structural abnormalities using magnetic resonance imaging (MRI) and VFA, and the association between cognitive function and VFA, in the elderly. A total of 2364 healthy individuals were enrolled, and we excluded those diagnosed with dementia. Participants were divided into a high-VFA and a low-VFA group based on median VFA. The high-VFA group had significantly lower cognitive function than the low-VFA group (p = 0.025), after adjustment for related factors using a linear regression model. Regarding brain structure in MRI, VFA remained significantly associated with white matter lesions (odds ratio (OR), 1.90; 95% confidence interval (1.33-2.70); adjusted p < 0.001) and perivascular space (OR, 1.28; 95% confidence interval (1.02-1.61); adjusted p = 0.033). Further follow-up studies are needed, but reducing visceral fat might be important, not only to prevent cardiovascular disease but also to prevent dementia.

All-cause and cardiovascular disease mortality in underweight patients with diabetic nephropathy: BioBank Japan cohort

We aimed to determine mortality risk in underweight patients with diabetic nephropathy for microalbuminuria or macroalbuminuria. We analyzed mortality and death-cause data from BioBank Japan, with baseline years 2003-2007. We analyzed mortality rates from all causes and ischemic heart disease, according to body mass index (<18.5, 18.5-21.9, 22-24.9 and ≥25 kg/m² ). The mean (standard deviation) of patient age, body mass index, and glycated hemoglobin at enrollment was 61.6 years (11.7 years), 25.0 kg/m² (4.4 kg/m² ) and 7.7% (1.5%), respectively. Hazard ratios of all-cause and ischemic heart disease mortality were highest (1.79 [P = 0.0001] and 2.95 [P = 0.027], respectively) in patients with body mass index <18.5 kg/m² , as compared with body mass index 22-24.9 kg/m² . All-cause mortality risk for body mass index <18.5 kg/m² was similar to that for current smokers (hazard ratio 1.70, P < 0.0001). Underweight could be a predictor of mortality risk in patients with diabetic nephropathy for microalbuminuria or macroalbuminuria.

Risk Factors for Dementia Incidence Based on Previous Results of the Specific Health Checkups in Japan

Dementia is a common disease in elderly people, with its prevalence expanding rapidly worldwide. Longitudinal and cohort studies on lifestyle and health conditions are needed to identify the risk of dementia. This study aimed to identify the risk factors for dementia incidence in Japan and to clarify the strategy for its primary care. In this study, an analysis was performed to investigate the association between the cognitive faculty level of the long-term care certification survey and the previous results of the specific health checkups in Japan. To investigate the risk factor for dementia incidence, a multivariable logistic regression analysis was performed, which showed a significant odds ratio for the incidence of dementia for two items, including abdominal circumference and insulin injections or oral hypoglycemic medications. The findings of our study suggested that a lower abdominal circumference had a higher risk for dementia incidence, and individuals who received insulin injections or oral hypoglycemic medications had a higher risk for dementia incidence based on the results of the health checkups conducted 10 years previously. Further, longer duration study with a larger sample is needed to identify the items from the specific health checkups that are associated with the risk of dementia.

Farm working experience could reduce late-life dependency duration among Japanese older adults: The Yamanashi Healthy-Active Life Expectancy cohort study based on the STROBE guidelines

With the advance of medical care, the duration of dependency on nursing care in later life has increased worldwide. There is a question of whether farm work could extend or shorten the dependency duration. We investigated the association between farm work experience and the duration of dependency on nursing support or care in late life.We randomly selected 600 adults aged ≥65 years, who were independent and not hospitalized, as part of the Yamanashi Healthy-Active Life Expectancy cohort and followed them for 13 years. We defined the duration of dependency as the time from reception of long-term care insurance benefits to death, and we adjusted for multiple covariates.We analyzed data from 225 adults (139 men and 86 women) who died during the follow-up period. Ninety four had received long-term care benefits. Mean age was 79.6 years (standard deviation [SD]: 6.3) in individuals with farm work experience and 80.1 years (SD: 7.2) in individuals without farm work experience. The estimated duration of dependency on long-term care was 1.3 years (standard error [SE]: 0.4) in individuals with farm work experience vs 2.1 years (SE: 0.5) in individuals without farm work experience (P = .01). The estimated duration of dependency in individuals with farm work experience and without farm work experience was 0.4 years (SE: 0.5) vs 1.3 years (SE: 0.6) in men respectively (P = .03) and 1.6 years (SE: 0.9) vs 2.4 years (SE: 0.9) in women, respectively (P = .16). The sensitivity analysis yielded an estimated duration of 1.2 years (SE: 0.5) in those with farm work experience and 2.3 years (SE: 0.5) in those without farm work experience (P = .004).Individuals with farm work experience required less long-term care prior to death, suggesting that agricultural and physical activities promote health. Policymakers focusing on preventing the need for nursing care in older populations could consider promoting farming or gardening.

Multiple Causes of Dementia as Engineered Senescence

All traumas—cranial, cardiovascular, hormone, viral, bacterial, fungi, parasites, misfolded protein, genetic, behavior, environmental and medication—affect the brain. This paper itemizes studies showing the many different causes of dementia including Alzheimer’s disease. Causes interact with each other, act sequentially by preparing the optimal conditions for its successor, initiate other diseases, allow for other traumas to accumulate and degrade protective features of the brain. Since such age-related cognitive impairment is not exclusively a human attribute there might be support for an evolutionary theory of dementia. Relying on theories of antagonistic pleiotropy and polymorphism, the brain has been designed to sequester trauma. Because of increased longevity, the short-term tactic of sequestering trauma becomes a long-term liability. We are engineered to sequester these insults until a tipping point is reached. Dementia is an evolutionary trade-off for longevity. We cannot cure dementia without understanding the overall biology of aging.