Purpose: The number of autopsy cases at our department of internal medicine for 20 years from September 1966 reached 1, 921. The autopsy rate stood at 91%. Of them, cases with stroke accounted for 1, 119 (59%). Taking up cerebral infarction and cerebral hemorrhage, we studied changes in type and risk factors for cerebral infarction.
Findings Those subjected to autopsy for stroke included 565 persons with cerebral infarction, 396 with cerebral hemorrhage and 158 with subarachnoid hemorrhage, but those with myocardial infarction accounted for only 107 (5%). In recent years, there has been an increasingly high incidence among old people, In the age group of 70 and over, cerebral infarction accounts for 65-70%, myocardial infarction 61-68% and cerebral hemorrhage 43-49%.
When the period is divided into the first and second halves, and the patients into the age group of 60 and over and the younger group to check changes in the prevalence of cerebral infarction and cerebral hemorrhage, it follows that the prevalence of cerebral infarction has been higher that than of cerebral hemorrhage in recent years, because the incidence of cerebral infarction in the age group of 60 and over has increased.
When the changes are analyzed with cerebral infarction and small infarction, we learn that the increase in the number of cases with infarction is ascribable to a rise in that of cases with large infarction or cortical branches. A check of the relationship between large infarction, atrial fibrillation and valvular disease reveals that tce increase in the incidence of large infarction stems from the infarction of old people afflicted with atrial fibrillation. A check of the relationshdp between the infarction of old people and hypertension and cholesterol indicates that the infarction is closely tied in with hypertension in past history and less correlated to hypercholesteremia. There still are fewer cases with infarction correlated to hyperlipemia than in the Western countries. For its prevention, it is important to control hypertension.

It is well known that extraordinarily high levels of erythrocyte concentration in the blood as observed in plethoric patients are a warning signal for cerebral apoplexy.
With radical changes in the social environment, psychogenic stress and cigarette smoking have pushed the incidence of erythrocytosis upward.
In rural areas, where anemia has traditionally been a major health threat, the nutritional conditions have been improved dramatically. Situations are such that more attention should be directed toward plethora.
The rise in Ht reading means the rise in blood viscosity, which could trigger off cerebral infarction in elderly people suffering from arteriosclerois.
People whose Ht reading is constantly high have a very high risk of cerebral apoplexy. Our survey of the people aged 70 and above found that the incidence of cerebral apoplexy was 50% in the Ht. 49-51% group and 100% in the Ht. 52% and above. The aged are easily affected by hemoconcentration due to dehydration. So, the slightest rise in Ht levels could lead to cerebral apoplexy. With a view to preventing the disease, the authors propose, the Ht. level of the old people should be kept below 43%.

Cerebral stroke in rural areas is a very important disease both from medical and social aspects. Among strokes, infarction which occurs most frequently in elderly persons is liable to result from atherosclerosis. And for the development of atherosclerosis, essential hypertension is the most important predisposing factor. Other than hypertension, aging, diabetes mellitus, hyperlipemia, esp. low HDL/Tch ratio, increased hematocrit values, coronary insufficiency, cardiac failure, arythmia, esp. atrial fibrillation, are also accepted important risk factors. Affirmative of such findings, the authors are convinced of the fact that atrial fibrillation which is increasing recently is closely related to both cerebral thrombosis and embolism.
But, in regard to cerebral infarction no signifying or trigger factor, similar to very high blood pressure, that trigger cerebral hemorrhage, is clarified as yet. It is made clear in this connection that cardiac failure predisposed by hypertensive heart disease in old age, assisted by pathophysiological and other environmental conditions, is the important factor. The authors also studied the clinical predisposing parameters and preventive measures about strokes.

Cerebrovascular disease is still considered a serious health problem in Japanese rural areas. The rate of death from the disease is very high. Many clinical and epidemiological studies have been conducted so far. However, they have failed to come up with answers effective for prediction and prevention of the scourge.
As part of the agricultural coop commissioned research project entitled “Study of Cerebral Apoplexy: Its Prediction and Prevention, ” we took a questionnaire survey in 1985-86, to obtain data as regards patients' subjective symptoms, electrocardiographic observations, hematological findings and many others before the onset of cerebral apoplexy. Five medical research institutes affiliated with the national welfare federation of agricultural cooperatives responded to our questionnaire.
As a result, the subjective symptoms that showed stochastically significant increases from one year to three months before the onset of the disease as a whole were fatigue, forgetfulness and insomnia. When it comes to cerebrovascular infarction, shortness of breath, angina, forgetfulness, and nocturia were particularly notable.
All these symptoms are not peculiar to cerebral apoplexy, but it should be noted that these are the warning signals of the killer disease.