| Co-Investigator(Kenkyū-buntansha) |
NAKANISHI Itiro Wakayama Medical University, Medical Department, Assistant teacher (40364088)
MORITA Shuhei Wakayama Medical University, Medical Department, Assistant teacher (50372868)
MIWA Hideto Wakayama Medical University, Medical Department, Assistant teacher (50231626)
KONDO Tomoyoshi Wakayama Medical University, Medical Department, Associate Professor (50103891)
UTUNOMIYA Hirotoshi Wakayama Medical University, Medical Department, Professor (60264876)
KIHIRA Tameko Wakayama Medical University, Medical Department, Assistant professor (30225015)
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| Research Abstract |
The number of ALS cases in Wakayama Prefecture encountered during the research (period from 1998 through 2002) was 134 (male: 79, female: 55). The crude average annual incidence in Wakayama prefecture in total was 2.50 (male: 3.08, female 1.99). In the Koza and Kozagawa areas in Wakayama prefecture, where a high incidence of ALS was reported 100 times higher in 1968 and as 9.54 in 1993, the average annual incidence of ALS in the present research was 5.24 (male: 7.34, female 3.18), when age-adjusted to the 1990 population. The prevalence in Wakayama prefecture at 31 December 2002 was 11.31 (male: 14.40, female: 8.53). In Koza and Kozagawa areas, the crude prevalence was 52.81 (male: 70.70, female: 38.28). These results indicate that the incidence of ALS in Wakayama prefecture, especially for females, has steadily decreased compared to that in previous reports. However, a high incidence of ALS has persisted among males in Wakayama prefecture, especially in the Koza and Kozagawa areas. So
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me environmental factors and gender specificity may be related to the decreased incidence of ALS in Wakayama prefecture.
In a comparison of year of onset before and after 1990, ALS patients in Wakayama Prefecture after 1990 had characteristics of older age onset and shorter clinical duration, and more frequently showed bulbar palsy onset compared with those before 1990. These findings indicated that younger onset patients with ALS decreased after 1990 in Wakayama Prefecture and this might partly explain the recent decline of ALS incidence in Wakayama Prefecture. The shift of the mean age at onset to older age might be due to exogenous factors, including changes in lifestyle, food, and drinking water in this area. Bulbar palsy onset and age at onset were expected as predictors of the survival rate.
To evaluate factors related to the disease, we conducted a retrospective case-control study. The neurological controls were 197 cases (<40 y) consecutively admitted to Wakayama Medical Hospital between 2000 and 2001. Association of cervical spondylosis or spinal spondylotic myelopathy (CS/SSM) with/without surgical treatment was compared between the ALS patients and the neurological controls. The occupations at the onset were compared among the ALS patients, the neurological controls and all the laborers more than 15 years old in Wakayama Prefecture. The number of definite or probable ALS patients by the El Escoriel criteria encountered between 1998 and 2003 was 204 (male: 120, female: 84). In the male subjects, OR of having ALS was 3.23 times higher who were associated with CS/SSM than that in the neurological controls without CS/SSM. OR of having ALS was 3.16 times higher in male subjects who had secondary industrial occupations, and 12.2 times higher who had both factors of CS/SSM and secondary industrial occupations. The percentage of the ALS patients with the tertiary industrial occupations was significantly lower than that of neurological controls and that of the laborers. CS/SSM, surgical treatment for myelopathy and occupathy and occupations are suspected to be some risk factors for developing/triggering or worsening ALS. Less
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