Prevalence of dementia in mainland China, Hong Kong and Taiwan: an updated systematic review and meta-analysis

High iron intake is associated with poor cognition among Chinese old adults and varied by weight status-a 15-y longitudinal study in 4852 adults

Background

High body iron status has been shown to be associated with adverse health outcomes. However, the relation between high body iron status, body mass index (BMI), and cognition is still understudied.

Objective

This study aimed to examine the association between iron intake and cognitive function in Chinese adults and tested the interaction effect of iron intake and BMI on cognition.

Design

Longitudinal study data from a nationwide sample (n = 4852; age ≥55 y) from the China Health and Nutrition Survey during 1991-2006 were used. Of the participants, 3302 had completed cognitive screening tests in ≥2 surveys. Cognitive function was assessed in 1997, 2000, 2004, and 2006. Dietary iron intake was obtained from a 3-d food record during home visits in 1991, 1993, 1997, 2000, 2004, and 2006. Multivariable mixed linear regression and logistic regression were used.

Results

The cumulative mean ± SD iron intake in 1997 of tested subjects was 23.7 ± 11.3 mg/d (25.4 mg/d in men and 22.2 mg/d in women). High iron intake was associated with poor cognition. In fully adjusted models, across the quartiles of iron intake the regression coefficients (95% CIs) were 0, -0.39 (-0.77, -0.01), -0.55 (-0.95, -0.15), and -0.90 (-1.33, -0.47), respectively. Comparing extreme quartiles of iron intake (high), the OR (95% CI) for poor cognitive function was 1.30 (1.04, 1.64). There was a significant interaction between iron intake and BMI. The association between high iron intake and poor cognition was stronger among those with a high BMI than those with a low BMI. Among those with a BMI (kg/m2) >24, across quartiles of iron intake the ORs (95% CIs) for poor cognitive function were 1.00, 1.27 (0.91, 1.78), 1.41 (0.97, 2.04), and 2.04 (1.38, 3.01), respectively.

Conclusion

Higher iron intake is associated with poor cognition in Chinese adults, especially among those with a high BMI.

A Prospective Association of Nut Consumption with Cognitive Function in Chinese Adults aged 55+ _ China Health and Nutrition Survey

OBJECTIVES

We aimed to investigate the association of nut intake with cognitive function in Chinese adults aged 55 and over.

DESIGN

This was a prospective open cohort study with repeated measurements of diet and cognition scores. Participants/settings: 4822 adults aged 55 and over participating in the China Health Nutrition Survey during 1991-2006.

MEASUREMENTS

Global cognitive function measured repeatedly in 1997, 2001, 2004, and 2006 using a subset of modified Telephone Interview for Cognitive Status; poor cognitive function was defined as cognition score<7. Nut consumption was collected using 3-day 24 recall method in 1991, 1993, and at surveys of cognition assessment.

STATISTICAL ANALYSES PERFORMED

Multilevel mixed effect linear regression and logistic regression analysis were conducted to assess the association with cognitive function.

RESULTS

The unadjusted cognitive score decreased by 0.29 (95% CI 0.22-0.28) with one-year aging during 1997-2006. Nut intake of more than 10g/d was associated with higher cognition score by 0.63 points (95% CI 0.15-1.12) or 40% less likely to have poor cognitive function (OR 0.60, 95% CI 0.43-0.84) after adjusted for demographic, lifestyle behavioural, BMI, and energy intake.

CONCLUSIONS

Nut consumption was inversely associated with cognition decline.

Global, regional, and national burden of Alzheimer's disease and other dementias, 1990-2016: a systematic analysis for the Global Burden of Disease Study 2016

BACKGROUND

The number of individuals living with dementia is increasing, negatively affecting families, communities, and health-care systems around the world. A successful response to these challenges requires an accurate understanding of the dementia disease burden. We aimed to present the first detailed analysis of the global prevalence, mortality, and overall burden of dementia as captured by the Global Burden of Diseases, Injuries, and Risk Factors (GBD) Study 2016, and highlight the most important messages for clinicians and neurologists.

METHODS

GBD 2016 obtained data on dementia from vital registration systems, published scientific literature and surveys, and data from health-service encounters on deaths, excess mortality, prevalence, and incidence from 195 countries and territories from 1990 to 2016, through systematic review and additional data-seeking efforts. To correct for differences in cause of death coding across time and locations, we modelled mortality due to dementia using prevalence data and estimates of excess mortality derived from countries that were most likely to code deaths to dementia relative to prevalence. Data were analysed by standardised methods to estimate deaths, prevalence, years of life lost (YLLs), years of life lived with disability (YLDs), and disability-adjusted life-years (DALYs; computed as the sum of YLLs and YLDs), and the fractions of these metrics that were attributable to four risk factors that met GBD criteria for assessment (high body-mass index [BMI], high fasting plasma glucose, smoking, and a diet high in sugar-sweetened beverages).

FINDINGS

In 2016, the global number of individuals who lived with dementia was 43·8 million (95% uncertainty interval [UI] 37·8-51·0), increased from 20.2 million (17·4-23·5) in 1990. This increase of 117% (95% UI 114-121) contrasted with a minor increase in age-standardised prevalence of 1·7% (1·0-2·4), from 701 cases (95% UI 602-815) per 100 000 population in 1990 to 712 cases (614-828) per 100 000 population in 2016. More women than men had dementia in 2016 (27·0 million, 95% UI 23·3-31·4, vs 16.8 million, 14.4-19.6), and dementia was the fifth leading cause of death globally, accounting for 2·4 million (95% UI 2·1-2·8) deaths. Overall, 28·8 million (95% UI 24·5-34·0) DALYs were attributed to dementia; 6·4 million (95% UI 3·4-10·5) of these could be attributed to the modifiable GBD risk factors of high BMI, high fasting plasma glucose, smoking, and a high intake of sugar-sweetened beverages.

INTERPRETATION

The global number of people living with dementia more than doubled from 1990 to 2016, mainly due to increases in population ageing and growth. Although differences in coding for causes of death and the heterogeneity in case-ascertainment methods constitute major challenges to the estimation of the burden of dementia, future analyses should improve on the methods for the correction of these biases. Until breakthroughs are made in prevention or curative treatment, dementia will constitute an increasing challenge to health-care systems worldwide.

FUNDING

Bill & Melinda Gates Foundation.

Related factors of cognitive impairment in community-dwelling older adults in Beijing Longitudinal Study of Aging

OBJECTIVES

To investigate the prevalence and related factors of cognitive impairment in community-dwelling older residents in Beijing, China.

METHODS

This is a cross-sectional study. A total of 2017 older individuals aged ≥ 60 years from Beijing Longitudinal Study of Aging were included in this study. Information on demographic characteristics, life style, chronic disease and geriatric syndromes was collected. Cognitive function was assessed by Mini-Mental State Examination.

RESULTS

The prevalence of cognitive impairment was 13.6% in community-dwelling older residents in Beijing. The prevalence of cognitive impairment was higher in women than it was in men and in rural areas than it was in urban areas, and increased with age. Logistic regression showed that older age [odds ratio (OR) = 1.496-3.033, P < 0.001], illiteracy (OR = 1.200-2.434, P = 0.003), low income (OR = 1.268-3.906, P = 0.005), less social participation (OR = 1.011-2.147, P = 0.044), stroke (OR = 1.410-3.305, P < 0.001), hearing loss (OR = 1.231-2.295, P = 0.001), depression (OR = 1.115-2.385, P = 0.012) and disability (OR = 2.315-4.681, P < 0.001) were independent risk factors for cognitive impairment.

CONCLUSIONS

The prevalence of cognitive impairment among the older adults in Beijing was high. More attention should be paid to the identification of and intervention for factors influencing cognitive impairment, and health education should be carried out to improve the quality of life of the older adults.

Blood-Derived Plasma Protein Biomarkers for Alzheimer's Disease in Han Chinese

It is well known that Alzheimer's disease (AD) is one of the most common progressive neurodegenerative diseases; it begins gradually, and therefore no effective medicine is administered in the beginning. Thus, early diagnosis and prevention of AD are crucial. The present study focused on comparing the plasma protein changes between patients with AD and their healthy counterparts, aiming to explore a specific protein panel as a potential biomarker for AD patients in Han Chinese. Hence, we recruited and collected plasma samples from 98 AD patients and 101 elderly healthy controls from Wuxi and Shanghai Mental Health Centers. Using a Luminex assay, we investigated the expression levels of fifty plasma proteins in these samples. Thirty-two out of 50 proteins were found to be significantly different between AD patients and healthy controls (P < 0.05). Furthermore, an eight-protein panel that included brain-derived neurotrophic factor (BDNF), angiotensinogen (AGT), insulin-like growth factor binding protein 2 (IGFBP-2), osteopontin (OPN), cathepsin D, serum amyloid P component (SAP), complement C4, and prealbumin (transthyretin, TTR) showed the highest determinative score for AD and healthy controls (all P = 0.00). In conclusion, these findings suggest that a combination of eight plasma proteins can serve as a promising diagnostic biomarker for AD with high sensitivity and specificity in Han Chinese populations; the eight plasma proteins were proven important for AD diagnosis by further cross-validation studies within the AD cohort.

Multicomponent intervention combining a cognitive stimulation group and tai chi to reduce cognitive decline among community-dwelling older adults with probable dementia: A multi-center, randomized controlled trial

OBJECTIVE

This research study aims to evaluate the effectiveness of a multicomponent intervention that combines a cognitive stimulation group and tai chi to reduce cognitive decline among community-dwelling Chinese older adults with probable dementia.

METHODS

A multi-center, randomized controlled trial design was adopted in this study. In addition to treat as usual, the treatment group (n = 41) participated in a structured cognitive stimulation group followed by tai chi twice a week, with a total of 14 sessions held during the study period. The control group (n = 39) received treat as usual. Mattis Dementia Rating Scale and Mini-Mental State Examination were used for assessing the cognitive abilities of participants in the pre- and post-treatment periods.

RESULTS

A 2 × 2 repeated measures analysis of covariance demonstrated that the treatment group was more effective than the control group on improving Dementia Rating Scale score (F = 7.45, p < .01) with a moderate effect size (partial eta square = .09) and Mini-Mental State Examination score (F = 9.96, p < .01) with a moderate to large effect size (partial eta square = .12) after controlling for age, gender, educational level, marital status, and number of physical illnesses.

CONCLUSION

The present study demonstrates the effectiveness of the multicomponent intervention on improving cognitive ability among community-dwelling older adults with probable dementia, suggesting that the multicomponent intervention can facilitate early identification, assessment, and treatment for community-dwelling older adults with probable dementia.