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Brief summary We evaluated the impact of seven risk factors for dementia in China. Physical inactivity, midlife hypertension and low education are proposed to be the largest fraction contributors to dementia. 55% of dementia were attributable to one or more of the seven risk factors. Background Previous studies have highlighted the impact of seven risk factors (midlife obesity, physical inactivity, smoking, low education, diabetes mellitus, midlife hypertension and depression) against dementia. However, the impact of these risk factors on dementia has not been evaluated among the Chinese population. Objective To clarify the impact of seven major risk factors on the incidence of dementia in China. Design The prevalence of risk factors was derived from the latest national surveys. Relative risks of corresponding risk factors were derived from the latest cohort or cross-sectional studies. Setting and subjects Three national surveys were included in the present study to obtain prevalence data of seven risk factors: the China Chronic Disease and Risk Factor Surveillance Survey (CCDRFSS) (2013), which covered about 170,000 adults (aged ≥18 years) from 31 provinces; (2) China National Survey of Chronic Kidney Disease (CNSCKD) (2010), which covered about 50,000 adults (aged ≥18 years) from 13 provinces; and (3) China Family Panel Studies Survey (CFPSS) (2012), which covered about 30,000 adults (aged ≥18 years) from 25 provinces. Methods Levin’s formula was used to calculate the population attributable fraction (PAF) for each risk factor for dementia. The combined PAF of the seven risk factors was calculated assuming the independence of each risk factor. Results Physical inactivity (PAF, 24.3%), midlife hypertension (PAF, 22.1%) and low education (PAF: 11.9%) were the top three factors that contributed to dementia. The total PAF of the seven risk factors was 55% in the Chinese population. Conclusions promotion of physical activity, control of hypertension and improvement of nationwide educational level may be helpful public health strategies to decrease the incidence of dementia in China.

ObjectiveThe aim of this study was to investigate the effect of a financial incentive on the number of daily walking steps among community-dwelling adults in Japan.Study designTwo-arm, parallel-group randomised controlled trial.Setting/participantsWe recruited physically inactive community-dwelling adults from Sendai city, Japan. Eligible participants were randomly allocated to an intervention or a wait list control group. Pedometers were used to assess the mean number of daily steps in three periods: baseline (weeks 1–3), intervention (weeks 4–6) and follow-up (weeks 7–9).InterventionThe intervention group was offered a financial incentive (shopping points) to meet the target number of increased daily steps in the intervention period.Main outcome measuresThe primary outcome was an increase in the mean number of daily steps in the intervention and follow-up periods compared with baseline.ResultsSeventy-two participants (69.4% women; mean age, 61.2±16.2 years; mean number of daily steps at baseline, 6364±2804) were randomised to the intervention (n=36) and control groups (n=36). During the intervention period, the increase in mean daily steps was significantly higher in the intervention group (1650, 95% CI=1182 to 2119) than in the control group (514, 95% CI=136 to 891; p<0.001). However, the difference between groups was not significant at follow-up after the incentives were removed (p=0.311). In addition, compared with controls, a significantly higher proportion of participants in the intervention group showed an increase in mean daily steps of ≥1000 (69.4% vs 30.6%, respectively; OR=5.17, 95% CI=1.89 to 14.08). There were no adverse effects from the intervention.ConclusionsThe present results suggest that financial incentives are effective in promoting short-term increases in physical activity.Trial registration numberUMIN000033276.

This study examined the effects of different food sources of protein on energy intake, body weight maintenance, and on the responses of plasma leptin, insulin and adiponectin in chronic high-fat diet-induced obese mice. Obesity was induced in 47 mice with a high-fat diet for 20 weeks. They were divided into five diet groups to test the effects of a higher protein proportion (30% energy), achieved at the expense of carbohydrate. For the next eight weeks, four of the groups were fed diets of chow formulated with whey, soy, red meat or milk while the control group continued on their high-fat diet. The results showed that: (i) increasing the protein : carbohydrate ratio (both at 30% energy) in a high-fat diet did not reduce the level of obesity; (ii) the type of protein added, however, did have a significant effect on the level of obesity attained; (iii) whey protein stabilised weight gain the most, had the strongest satiety effects and also stimulated the highest production of adiponectin; and (iv) whey protein also was associated with the lowest insulin values among all proteins tested. Plasma leptin levels were not affected by any of the diets. Dietary fat remains a potent factor in weight management, but the type and amount of protein may also be important through its effects on food intake. In particular, the apparent decreased appetite associated with increased adiponectin in the whey-based high-protein diet may contribute to stabilised body mass in chronic high-fat diet-induced obesity.

Altruistic social activity, such as giving support to others, has shown protective benefits on dementia risk and cognitive decline. However, the pathological mechanism is unclear. In the present study, we investigated the association between altruistic social activity and brain regional gray matter. Furthermore, to explore the psychological interplay in altruistic social activity, we tested mediating effect of depressive symptoms on brain regional gray matter. We performed a cross-sectional Voxel-Based Morphology (VBM) analysis including 8695 old adults (72.9±6.1 years) from Japan Prospective Studies Collaboration for Aging and Dementia (JPSC-AD) Cohort. We measured altruistic social activities by self-report questionnaire, depressive symptoms by Geriatric Depression Scale (GDS)-short version. We employed the whole-brain VBM method to detect relevant structural properties related to altruistic social activity. We then performed multiple regression models to detect the mediating effect of depressive symptoms on particular brain regional gray matter volume while adjusting possible physical and social lifestyle covariables. We found that altruistic social activity is associated with larger gray matter volume in posterior insula, middle cingulate gyrus, hippocampus, thalamus, superior temporal gyrus, anterior orbital gyrus, and middle occipital gyrus. Depressive symptoms mediated over 10% on altruistic social activity and hippocampus volume, over 20% on altruistic social activity and cingulate gyrus volume. Our results indicated that altruistic social activity might preserve brain regional gray matter where are sensitive to aging and cognitive decline. Meanwhile, this association may be explained by indirect effect on depressive symptoms, suggesting that altruistic social activity may mitigate the neuropathology of dementia.