We investigated seasonal variation in the incidence of cerebral stroke among the general population aged >40 years in November of 1961 in Hisayama, Japan. During the 24-year follow-up period, 311 cases of cerebrovascular diseases occurred. The date or month of onset was determined in 308 cases, of which 51 were classified as intracerebral hemorrhage, 223 as cerebral infarction, and 27 as subarachnoid hemorrhage. We observed a significant seasonality in the incidence of all stroke (p<0.01), of intracerebral hemorrhage (p<0.05), and of cerebral infarction (p<0.01), whereas subarachnoid hemorrhage had no significant seasonal pattern. Subjects <64 years of age showed a significant seasonal variation in the incidence of both intracerebral hemorrhage (p<0.05) and cerebral infarction (p<0.01). A significant seasonal pattern for the incidence of intracerebral hemorrhage was also noted among persons with hypertension (p<0.05) or a high serum cholesterol level (p<0.05), whereas such a pattern for cerebral infarction was documented among normotensive persons (p<0.05) and those with a low serum cholesterol level (p<0.01). In addition, the incidences of intracerebral hemorrhage and cerebral infarction were negatively correlated with mean ambient temperature (p<0.01 and p<0.05, respectively), and all stroke and intracerebral hemorrhage in men were significantly related to intradiurnal temperature change (/><0.05 and p<0.01, respectively). and Denmark 13 ; there is agreement among these reports that the incidence of onset of cerebrovascular diseases peaks in the winter-spring and has a trough in the summer-autumn, related to ambient temperature. On the other hand, reports from Yugoslavia, 14 Mexico, 15 and Brazil 16 have found no seasonality or relation to temperature in stroke rates. However, data for all those studies were based on hospitalized patients or mortality statistics. Little is known about seasonality of the incidence of cerebrovascular diseases among the general population.From the Second Department of Internal Medicine, Faculty of Medicine, Kyushu University, Fukuoka, Japan.Supported in part by research grants for Cardiovascular Disease from the Ministry of Health and Welfare, Japan, and facilitated by the Japan-U.S. Cooperative Agreement in the Cardiovascular Area, the Japanese National Cardiovascular Center, and the National Heart, Lung, and Blood Institute.Address for correspondence: Atsushi Shinkawa, MD, Second Department of Internal Medicine, Faculty of Medicine, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka, 812 Japan. Received October 13, 1989; accepted April 23, 1990.The aim of our study is to elucidate in a long-term prospective population survey conducted in Hisayama, Japan, the seasonal variation in the incidence of stroke and the influence of traditional risk factors for cerebrovascular diseases and environmental factors on the seasonality of the onset of cerebrovascular diseases. We selected sex, age at onset, blood pressure, and serum cholesterol concentration as the traditional risk facto...

We 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.

Background and Purpose:We sought to determine the type-specific prevalence of dementia and its risk factors in elderly persons from the Japanese community of Hisayama.Methods: We studied the prevalence of dementia in 887 Hisayama residents (353 men and 534 women) aged 65 years or older (screening rate, 94.6%) using various items of clinical information, neurological examination, and dementia scales. We also studied brain morphology in 50 of 59 determined to have dementia by computed tomography or autopsy during the subsequent 54 -month period. Factors relevant to dementia were compared between 27 patients with vascular dementia and 789 control subjects without dementia in a retrospective fashion.Results: The prevalence rate of dementia among Hisayama residents aged 65 or older was estimated at 6.7%, with a females to males ratio of 1:2. Among 50 cases of dementia in which brain morphology was examined, the frequency of vascular dementia was 56%; this rate was 2.2 times higher than that for senile dementia of the Alzheimer type. Aging, hypertension, electrocardiographic abnormalities, and high hematocrit were significantly (p<0.05) and independently associated with the occurrence of vascular dementia.Conclusions: Prevalence of dementia among the Hisayama residents was relatively identical to that previously reported, but vascular dementia was more predominant Risk factors for vascular dementia were similar to those for lacunar infarcts. Control of hypertension may be a key to reducing dementia among the Japanese population. (Stroke 1992;23:798-803) KEY WORDS • dementia • epidemiology • Japan • risk factors

The incidence of intracerebral hemorrhage over 13 years is compared between two Hisayama cohorts. Among men aged 40 years or older, the annual incidence declined significantly from 3.1/1,000 in the early cohort (1961-1970) to 1.2/1,000 in the recent cohort (1974-1983). Massive ganglionic hemorrhage decreased, while small or medium-sized intracerebral hemorrhage increased in the recent cohort on pathologic or computed tomographic examination. These trends could be due to the reduced prevalence of hypertension in the Hisayama population. The association of serum total cholesterol with intracerebral hemorrhage is discussed based on the results during a 22-year follow-up period.

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%).

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SUMMARY l b elucidate the relation of hematocrit (Hct) to the incidence of cerebral infarction, a prospective follow-up study of 16 years (1965-81) was performed in a general population sample of 1220 Hisayama residents aged 44 and over, of both sexes. Most of the subjects who died during the follow-up period were autopskd, the rate being 89.0%.Hct decreased with advancing age in men, but not in women. The average value for Hct was significantly lower in women than in men. According to the mean value ± 1 SD of Hct, the subjects were grouped into 3, in each sex as follows: low (<35%), normal (35-45%) and high (2=45%) for men, and, low (<30%), normal (30-40%) and high (2:40%) for women.During the follow-up period, cerebral infarction occurred in 117 patients. The cumulative incidence of cerebral infarction In the low Hct group for men was the lowest, even after adjustments for age and blood pressure. Conversely, the incidence in the low Hct group of women was significantly higher than that in the normal Hct group and was consistently increased with tune during 2-5 years of the follow-up. After the 6th year or later, however, the incidence was gradually but significantly increased hi the Ugh Hct group, compared with the normal Hct group. Since Hct levels were related with other variables such as serum total cholesterol, serum total protein, Quetelet index and prevalence of hypertension in both sexes, heavy alcohol consumption in men, and glucose Intolerance in women, such variables were taken into account using Cox's proportional hazards regression model. The low Hct in women remained important as an independent risk factor of cerebral Infarction.The sex difference hi the role of Hct as a cause of cerebral infarction was discussed, taking into consideration the interrelationship between Hct and other risk factors.

The use of a screening test for thyroid functional disorder by sensitive thyroid stimulating hormone assay in the elderly was investigated. The basal thyroid stimulating hormone levels predicted the response of thyroid stimulating hormone to thyrotropin releasing hormone; it was suppressed in 99 (99.0%) of 100 hyperthyroid patients. Therefore, not only primary hypothyroidism but also hyperthyroidism can be excluded when the serum thyroid stimulating hormone levels are normal. An epidemiological study was then performed on 2,421 (76.7%) of the Japanese general population aged 40 or over recruited from the residents in Hisayama town and also in 122 residents between 20 and 40 years of age. Additional free T4 measurement was necessary in about 10% of the residents with abnormal TSH levels to confirm the diagnosis of hyperthyroidism or distinguish latent from overt hypothyroidism. There was a significant correlation between age and serum thyroid stimulating hormone levels after logarithmic conversion (r = 0.1533, P less than .001). The prevalence of thyroid dysfunction found in 1,026 males and in 1,395 females aged 40 or over was, respectively: hyperthyroidism, less than 0.1% and 0.2%, latent (subclinical) hypothyroidism, 3.2% and 5.5%, and overt hypothyroidism, 0.4% and 0.7%. We conclude that the screening with this sensitive thyroid stimulating hormone assay and additional free T4 measurement is useful for detection of patients with thyroid functional disorder.