Takao Ohmura

Incidence and risk factors of vascular dementia and Alzheimer's disease in a defined elderly Japanese population The Hisayama Study

Article abstract—We followed 828 nondemented residents of Hisayama Town, Kyushu, Japan, aged 65 years or older (88.3% of the elderly population) for 7 years starting in 1985 in order to determine the type-specific incidence of dementia and its risk factors in the general Japanese population. Only two subjects were lost to the follow-up, during which period 103 subjects developed dementia. Morphologic examination of the brains of 89 subjects (86.4%) was made by autopsy or CT. We made the initial diagnosis of dementia based on the DSM-111-R criteria, with the diagnoses of vascular dementia (VD) being based on the NINDS-AIREN criteria and Alzheimers disease (AD) on the NINCDS-ADRDA criteria. The incidence of VD and AD increased with age for both sexes. The age-adjusted total incidence (per 1,000 person-years) of dementia was 19.3 for men and 20.9 for women. The corresponding rates for VD were 12.2 for men and 9.0 for women, and for AD, 5.1 for men and 10.9 for women. Among the VD subjects whose brain morphology we examined, the most frequent type of stroke was multiple lacunar infarcts (42%), but half these subjects lacked a stroke episode in their histories. Multivariate analysis showed that age, prior stroke episodes, systolic blood pressure, and alcohol consumption were significant independent risk factors for the occurrence of VD. In contrast, age and a low score on Hasegawas dementia scale were significant risk factors for AD, and physical activity was a significant preventive factor for AD. Our findings suggest that asymptomatic stroke is an important factor in the development of VD, with age, prior stroke episodes, systolic blood pressure, and alcohol consumption being independent risk factors for its occurrence. Age and a low scare on Hasegawas dementia scale are significant risk factors for AD, with moderate physical activity having a statistically significant preventive effect.

Diabetes and cardiovascular disease in a prospective population survey in Japan : The Hisayama study

To elucidate the effect of glucose intolerance on cardiovascular disease in the current Japanese population, we performed a 75-g oral glucose tolerance test in 2,427 Hisayama residents aged 40–79 years in 1988, who were free from a previous history of stroke or myocardial infarction, and followed them prospectively for 5 years. The prevalence of diabetes (NIDDM) among men was 13% and that of impaired glucose tolerance (IGT) was 20%; the corresponding values for women were 9 and 19%, respectively. The age- and sex-adjusted incidence of cerebral infarction (6.5 per 1,000 person-years, P 0.01) and coronary heart disease (5.0 per 1,000 person-years, P 0.05) was significantly higher in subjects with NIDDM than in those with normal glucose tolerance (1.9 and 1.6 per 1,000 person-years, respectively). In addition, subjects with IGT and NIDDM had a higher risk of cardiovascular disease including stroke and coronary heart disease than did those with normal glucose tolerance after adjustment for age and sex, namely the relative risk for IGT was 1.9 (95% CI 1.2–3.2), and the relative risk for NIDDM was 3.0 (95% CI 1.8–5.2). These associations remained significant even after controlling for six other risk factors including hypertension in multivariate analysis. Our data suggest that NIDDM is a significant risk factor for both cerebral infarction and coronary heart disease and also that IGT itself is a risk factor for cardiovascular disease in the general Japanese population today.

Prevalence of Type 2 (non-insulin-dependent) diabetes mellitus and impaired glucose tolerance in the Japanese general population: the Hisayama study

SummaryWe determined the population-based prevalence of diabetes mellitus in members of the Japanese community, Hisayama aged 40–79 years old by a 75-g oral glucose tolerance test. The basic population used to calculate diabetic prevalence was 1,077 men (72.8% of the whole population in the same age range) and 1,413 women (80.8%) including ten diabetic patients on insulin therapy. In addition, we compared the prevalence of history of diabetes which was acquired by interview or questionnaire, between participants and non-participants in the 75-g oral glucose tolerance test, but they were not statistically different. The age-adjusted prevalence of diabetes to world population was 12.7% for men and 8.4% for women, and that of impaired glucose tolerance was 19.6% for men and 18.4% for women. These figures were much higher than those previously reported from several Japanese communities. The results obtained from the present study could reveal true prevalence of diabetes among the Japanese population. In addition, the reasons for the increasing prevalence of diabetes among the recent Japanese population are also discussed.

Incidence and prognosis of subarachnoid hemorrhage in a Japanese rural community.

Twenty-six first episodes of subarachnoid hemorrhage occurred among 1,621 Hisayama residents aged greater than or equal to 40 years during the 22-year follow-up of a prospective study. Subarachnoid hemorrhage was confirmed by both clinical and autopsy findings. The average annual incidence (96.1/100,000 population) was 3-13 times higher than any previously reported and steeply increased with age in both sexes, being 2.3 times higher for women than for men after adjusting for age. Nine patients (35%) died less than or equal to 8 hours after the onset of subarachnoid hemorrhage. None was correctly diagnosed on the death certificates, and four of the nine (44%) were misdiagnosed as intracerebral hemorrhage. We found the survival rate of patients suffering subarachnoid hemorrhage to be much lower than previously reported because we detected a large number of sudden deaths due to subarachnoid hemorrhage through the high rate of autopsy in our cohort (81.4%).

Changing Patterns in the Prevalence of Dementia in a Japanese Community: The Hisayama Study

We compared type-specific prevalences of dementia between two surveys of Hisayama residents > or = 65 years old conducted in 1985 and 1992. The overall age-adjusted prevalence was greatly decreased from 5.4% in 1985 to 3.3% in 1992 for men, while it was changed little from 7.5 to 6.3% for women. The prevalence of vascular dementia (VD) decreased during the intervening 7 years in men but not in women. The prevalence of Alzheimers type (SDAT) was the same in either sex. The ratio of VD to SDAT prevalence was 1.8 in 1985 but fell to 1.1 in 1992. The background factors responsible for this change are discussed.

The association of the insulin resistance syndrome with impaired glucose tolerance and NIDDM in the Japanese general population: the Hisayama study

SummaryTo elucidate the risk factors for initiating glucose intolerance, the relevant factors were explored in a cross-sectional survey conducted in a sample population aged 40–79 years old selected from a Japanese community, Hisayama, Japan in 1988. A 75-g oral glucose tolerance test was used to classify 1,073 men (72.5% of the entire population in the same age range) and 1,407 women (80.5%) into normal, impaired glucose tolerance and diabetes mellitus groups. In all age and sex groups with normal glucose tolerance, the sum of fasting and 2-h post-load insulin values varied widely and demonstrated significant positive correlations with triglycerides, body mass index, waist-hip ratio, systolic and diastolic blood pressure, while it negatively correlated to HDL cholesterol (p<0.05). Insulin resistance was presumed to develop in normal glucose tolerance subjects with hyperinsulinaemia. The sum of the insulin concentrations, triglycerides, body mass index, waist-hip ratio and blood pressure levels was significantly associated with impaired glucose tolerance in all age and sex groups after adjustment for age (p<0.05) and was also related to diabetes in either all or some age and sex groups, respectively (p<0.05). It was shown that glucose intolerance in the general population was associated with the factors related to insulin resistance. These cross-sectional data, therefore, support the hypothesis that insulin resistance is the primary defect in the development of glucose intolerance in the Japanese general population. However, a further prospective study is still needed in order to confirm this hypothesis.

Hyperinsulinaemia and blood pressure in a general Japanese population : the Hisayama study

Objectives To study the relationship between serum insulin and blood pressure, as well as the prevalence of hypertension according to the insulin level in a general Japanese population. Design In 1988 a cross-sectional community survey was conducted among Hisayama residents aged 40–79 years. Methods A total of 1073 males and 1407 females (72.5 and 80.5% of the total population, respectively) underwent comprehensive investigation, including a 75-g oral glucose-tolerance test. Fasting and 2-h serum insulin levels were measured by radioimmunoassay. Results The sum of the fasting and 2-h postloading insulin levels was significantly correlated with the systolic blood pressure (SBP; r = 0.18 and 0.26 for males and females, respectively) and the diastolic blood pressure (DBP; r = 0.24 and 0.19, respectively) in the subjects not receiving antihypertensive drugs. In multiple regression analysis the correlation with blood pressure remained significant in both sexes even after controlling for age, body mass index, alcohol intake, smoking, a family history of hypertension, serum total cholesterol and fasting plasma glucose. The age- and sex-adjusted prevalence of hypertension (SBP ≥ 160mmHg or DBP ≥ 95mmHg, or both, or receiving drug treatment) increased significantly with an increase in the sum of fasting and 2-h postload insulin levels in both the non-obese subjects (body mass index <25 kg/m2) and the obese subjects (body mass index ≥ 25kg/m2). Multiple logistic regression showed that the sum of fasting and 2-h postload insulin levels was a significant factor with an independent relationship to hypertension, even after taking the other risk factors into account. Conclusion The present study suggests that hyperinsulinaemia is related to hypertension in a general Japanese population.

Causes of Death in the Elderly and Their Changing Pattern in Hisayama, a Japanese Community: Results From a Long-Term and Autopsy-Based Study

The causes of death for the elderly were prospectively studied in Hisayama, Japan, a rural community. We compared 1,621 subjects, aged 40 years or over, recruited in 1961, and 2,053 subjects recruited in 1974. Each cohort was studied in a follow‐up that lasted 10 years; they had autopsy rates of 82.1% and 86.1% during each 10‐year period, respectively. The most common causes of death for those aged 70 years or over were cerebrovascular disease, malignant neoplasms, and pneumonia. Deaths due to cerebrovascular disease tended to decrease in the recent cohort, but the proportion of decline was more prominent in cases aged 40 to 69 years. There was a sex difference in the changing pattern of mortality from heart diseases including ischemic heart disease. Deaths by both heart diseases and ischemic heart disease increased in the more recent cohort of aged women, whereas they decreased in the aged men. Pneumonia was an important cause of death for the elderly in both cohorts. Deaths due to “senility” were rare, being only 1% of the deceased aged 70 or over. With prolonged lifespan, especially for women, the impact of atherosclerosis and its related disorders on the recent Japanese aged population appears to have increased.

Malignant neoplasms in the Japanese community of Hisayama: Mortality and changing pattern during a 30-year observation period based on a consecutive autopsy series

To obtain a relatively true mortality from malignant neoplasms, we studied the frequency of cancers in the different sites and the changing patterns of the frequency and sites over time among residents of the community of Hisayama, where an autopsy-based population survey (autopsy rate, 80%) has been conducted since 191. During the 30-year period from 1962 to 1991, we found 438 malignant neoplasms in 407 cases among 1,250 consecutive autopsies. Stomach cancer was not frequent in type of cancer, with 123 cases (9.8%), followed by lung cancer in 62 (5.0%), colorectal cancer in 42 (3.4%), liver cancer in 37 (3.0%), and pancreatic cancer in 30 (2.4%). We compared the mortality from cancers for both autopsy and nonautopsy cases (the proportional mortality) among three 10-year periods. The proportional mortality from all cancers, as well as for lung, colorectal, and liver cancers, showed an increase in recent years, while stomach and pancreatic cancer showed a decrease. These figures were nearly similar to the mortality statistics for the Japanese population as a whole except for the observed decreasing trend in mortality from pancreatic cancer.