Dataset Information

Information processing speed and 8-year mortality among community-dwelling elderly Japanese.

ABSTRACT:

Background

Cognitive function is an important contributor to health among elderly adults. One reliable measure of cognitive functioning is information processing speed, which can predict incident dementia and is longitudinally related to the incidence of functional dependence. Few studies have examined the association between information processing speed and mortality. This 8-year prospective cohort study design with mortality surveillance examined the longitudinal relationship between information processing speed and all-cause mortality among community-dwelling elderly Japanese.

Methods

A total of 440 men and 371 women aged 70 years or older participated in this study. The Digit Symbol Substitution Test (DSST) was used to assess information processing speed. DSST score was used as an independent variable, and age, sex, education level, depressive symptoms, chronic disease, sensory deficit, instrumental activities of daily living, walking speed, and cognitive impairment were used as covariates.

Results

During the follow-up period, 182 participants (133 men and 49 women) died. A multivariate Cox proportional hazards model showed that lower DSST score was associated with increased risk of mortality (hazard ratio [HR] = 1.62, 95% CI = 0.97-2.72; HR = 1.73, 95% CI = 1.05-2.87; and HR = 2.55, 95% CI = 1.51-4.29, for the third, second, and first quartiles of DSST score, respectively).

Conclusions

Slower information processing speed was associated with shorter survival among elderly Japanese.

SUBMITTER: Iwasa H

PROVIDER: S-EPMC3872525 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Publications

Information processing speed and 8-year mortality among community-dwelling elderly Japanese.

Iwasa Hajime H Kai Ichiro I Yoshida Yuko Y Suzuki Takao T Kim Hunkyung H Yoshida Hideyo H

Journal of epidemiology 20131116 1

<h4>Background</h4>Cognitive function is an important contributor to health among elderly adults. One reliable measure of cognitive functioning is information processing speed, which can predict incident dementia and is longitudinally related to the incidence of functional dependence. Few studies have examined the association between information processing speed and mortality. This 8-year prospective cohort study design with mortality surveillance examined the longitudinal relationship between i ...[more]

PMID: 24240629

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Project description:BackgroundHyperglycemia is believed to be a risk factor for cognitive decline, but the longitudinal relationship between hyperglycemia and cognitive decline in the Japanese population is unclear. The present study aimed to clarify the association between blood glucose levels and information processing ability in middle-aged and older adults.MethodsThe subjects were 866 men and 815 women aged 40-79 years not taking medication for diabetes who participated in the first study wave (1997-2000) and then participated at least once in the subsequent six study waves (2000-2012) of the National Institute for Longevity Sciences-Longitudinal Study of Aging, Japan. Hemoglobin A1c (HbA1c) levels were categorized into four groups (< 5.6, 5.6 to < 6.0, 6.0 to < 6.5, ≥ 6.5%), and a mixed-effects model was used to evaluate the effects of the HbA1c level (four groups) on repeated measures of information processing speed. The models also included baseline age, body mass index, ethanol intake, smoking status, educational level, family income, and history of stroke, hypertension, heart disease, and dyslipidemia as covariates.ResultsMean (standard deviation) HbA1c and follow-up time in participants were 5.2 (0.5) % and 10.0 (3.6) years, respectively. A linear mixed model showed that the main effect of the four HbA1c groups on information processing ability was not significant in either men or women, but the interaction of HbA1c and time with information processing speed in the higher HbA1c level groups (≥ 6.5% group in men, 6.0 to < 6.5% and ≥ 6.5% groups in women) was significant compared to the lower HbA1c level (< 5.6%) group (P < 0.05). When the slope of information processing speed by HbA1c level at baseline was examined, the slope of information processing speed in the higher HbA1c level (≥ 6.5%) group was higher than in the lower HbA1c level (< 5.6%) group, both in men (- 0.31/year) and in women (- 0.30/year), as well as in women with an HbA1c level of 6.0 to < 6.5% (- 0.40/year).ConclusionsHigher baseline HbA1c was associated with greater subsequent decline in information processing ability in Japanese community dwellers, even with the pre-clinical HbA1c level (6.0 to < 6.5%) in women. The results suggest that good glycemic control or prevention of hyperglycemia may contribute to maintaining information processing ability.

Project description:Anemia is one of the most common health problems in the elderly in low and middle income countries. Evidence from studies in high income countries suggests that the presence of anemia may predict mortality. We aimed to estimate the prevalence of anemia and the determine the relationship of hemoglobin, mean corpuscular volume (MCV) and mortality in community dwelling Thai elderly. Data from subjects aged ≥ 60 years from the Fourth Thai National Health Examination Survey were analyzed. Comorbidity and hematologic indexes including MCV were obtained. The Cox proportional hazard model was applied to explore associations with mortality. Data from 8,935 subjects were obtained. The mean age of participants was 69.2 years (SD 6.8). 3446 (38.2%) of subjects had anemia; 1931(56%) of these were classified as mild and normocytic. With a total 51,268 person-year of follow up, 753 participants with anemia died, and the cumulative all-cause mortality was 38.5 per 1,000 person-years. The presence of anemia was associated with an increased risk of mortality with HR of 1.66 (95% CI = 1.50-1.84 , p < 0.001). Among subjects with low MCV, hemoglobin level < 10 g/dl in men and < 9 g/dl in women significantly increased the risk of mortality (HR of 2.71, 95% CI = 1.88-3.91 and HR of 3.14, 95%CI = 2.11-4.67, respectively) Persons with anemia and normal MCV, the association with mortality was evident at hemoglobin levels below 11 g/dl for both males and females. (HR of 1.98, 95% CI = 1.67-2.35). Anemia is a moderate to severe public health significant in the population for community dwelling elderly in Thailand. At the same level of Hemoglobin, low MCV population seem to have lower mortality rate than normal MCV. Systematic screening for anemia should be implemented to identify patients at increased risk of mortality. The future research should be focus on causes of anemia and factors contributing to increased mortality in normal to high MCV would be of interest. If this could lead to identifying modifiable causes, it would be beneficial for improving mortality risk among older people.

Dataset Information

Information processing speed and 8-year mortality among community-dwelling elderly Japanese.

Background

Methods

Results

Conclusions

Publications

Information processing speed and 8-year mortality among community-dwelling elderly Japanese.

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