[Increased incidence of senile dementia in the Hansen's disease sanatoriums of Japan].

In 1973, Narita reported that the rate of demented patients above 65 years was about 2% at the sanatorium--Tama Zenshoen, which was much lower than that of the average aged people (4-5%). The reason for that was thought to be due to the acquirement of strong mind under loneliness and difficulties faced by the patients through social enforcement to live in isolation. From that report on the low percentage of dementia among the Japanese Hansen patients reemed to be widely accepted. Fifteen years later in 1988, Narita reported that the rate of demented patients above 65 years was 3.2% in males and 3.6% in females indicating still a low rate at Tama Zenshoen. In 1994, however, Narita found unexpectedly that the percentage of dementia among patients above 80 at Tama Zenshoen was higher than the average aged population. Therefore in this report, we tried to analyze the reason for this difference. In addition to Tama Zenshoen patients, we also investigated those of another Hansen disease sanatorium namely Nagashima Aiseien which has similar structural organization as Tama Zenshoen. A comparison of dementia between these two was carried out, taking patients above 65 years as the study group (Used GBS scale based on Karasawa's method). In Tama Zenshoen, the rate of patients with dementia was 18.6% in males and 31% in females. Above 80 years those were 54.4% in males and 75.9% in females. The reason for the above high rate of dementia may be probably due to the passage of long years (40 to 50 years) after the enforcement to live in isolation causing the weakening of the spirit. The patients might have got some mental support if they had offspring, but they had no way to have any under the forced contraception. On the contrary, in Nagashima Aiseisen, the percentage of patients with dementia was low, namely 3.6% in males and 9.1% in females. In those patients above 80 years, it was 2.7% in males and 6.8% in females, those were almost similar to the average normal population (6%). Such a big difference was quite surprising. The reason behind this difference, may be due to the construction of the houses for the disabled persons. Both Nagashima Aiseien and Tama Zenshoen, have small individual rooms. In Tama Zenshoen, patients are able to visit their close neighbor, only after changing their shoes or with the aid of wheel chairs, but in Nagashima Aiseien, the corridors connecting quarters allow the patients to move easily to his neighbors with bare feet or even with crawl. Therefore, in Nagashima Aiseien, the number of patients who have social contacts with their neighbors is much greater in number which make them mentally active, thus eliminating the major factors affecting dementia. We can conclude that such communication between friends and co-mates make them alert and keep the spirit in the aged.