Epidemiology of motor neuron disease in the Kii Peninsula of Japan, 1989–1993: Active or disappearing focus?

• Published in: Journal of the neurological sciences Vol. 155; no. 2; pp. 146 - 155
• Main Authors: Yoshida, Sohei, Uebayashi, Yushiro, Kihira, Tameko, Kohmoto, Junko, Wakayama, Ikuro, Taguchi, Seiichiro, Yase, Yoshiro
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier B.V 05.03.1998; Elsevier Science
• Subjects: Adult; Age Factors; Age of Onset; Aged; Aged, 80 and over; Amyotrophic lateral sclerosis; Amyotrophic Lateral Sclerosis - diagnosis; Amyotrophic Lateral Sclerosis - epidemiology; Biological and medical sciences; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; Emigration; Female; Humans; Incidence; Japan - epidemiology; Kii Peninsula of Japan; Kozagawa focus; Male; Medical sciences; Middle Aged; Motor neuron disease; Motor Neuron Disease - diagnosis; Motor Neuron Disease - epidemiology; Neurology; Sex Factors; Asia; Japan; Emigration; Amyotrophic lateral sclerosis; Kii Peninsula of Japan; Kozagawa focus; Motor neuron disease; Incidence; Human; Nervous system diseases; Prevalence; Epidemiologic center; Epidemiology; Geographic distribution; Central nervous system disease; Evolution; Degenerative disease; Spinal cord disease; Public health
• ISSN: 0022-510X; 1878-5883
• DOI: 10.1016/S0022-510X(97)00300-6

During the period 1989–1993, the incidence and migration patterns of patients with motor neuron diseases (MND) in Wakayama Prefecture, including one of the high-incidence Kii Peninsula foci (‘Kozagawa focus’), were surveyed to determine whether the focus had truly disappeared or not. Overall, the crude average annual incidence was 1.43 per 100 000 population; when age-adjusted to the 1990 Japanese population, it was 1.25 (1.85 for males and 0.61 for females). The average annual age- and sex-specific incidence steadily increased to a peak between 60 and 69 years and dropped after 70. Geographically, the rates varied in the five regions of Wakayama Prefecture from 0.38 to 2.48. The areas with high incidence were distributed in the central and southernmost regions; the highest was in the Kozagawa focus with 9.54 (two ALS cases within five years; 4193 base population, 1990). During the study period, four emigrants from Kozagawa had developed MND one to four decades after leaving the focus. Although the remarkable clustering of MND was thought to have disappeared, the southern Kii Peninsula remains a high-risk area for MND, especially if one interprets the data so as to include the emigrants. In general, the age at onset has increased in the past 20 years from 56.5 to 61.7; male predominance is observed.