Tohoku J. Exp. Med., 2005, 205(1)

The Severity of Minamata Disease Declined in 25 Years: Temporal Profile of the Neurological Findings Analyzed by Multiple Logistic Regression Model

MAKOTO UCHINO, TERUYUKI HIRANO, HIROSHI SATOH,¹ KIMIYOSHI ARIMURA,² MASANORI NAKAGAWA³ and JYUNJI WAKAMIYA⁴

Department of Neurology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, ¹Neurology, Minamata City General Hospital and Medical Center, Minamata, ²Department of Neurology, Graduate School of Medical Sciences, Kagoshima University, Kagoshima, ³Department of Neurology, Kyoto Prefectural University of Medicine, Kyoto, and ⁴National Institute for Minamata Disease, Minamata, Japan

Minamata disease (MD) was caused by ingestion of seafood from the methylmercury-contaminated areas. Although 50 years have passed since the discovery of MD, there have been only a few studies on the temporal profile of neurological findings in certified MD patients. Thus, we evaluated changes in neurological symptoms and signs of MD using discriminants by multiple logistic regression analysis. The severity of predictive index declined in 25 years in most of the patients. Only a few patients showed aggravation of neurological findings, which was due to complications such as spino-cerebellar degeneration. Patients with chronic MD aged over 45 years had several concomitant diseases so that their clinical pictures were complicated. It was difficult to differentiate chronic MD using statistically established discriminants based on sensory disturabance alone. In conclusion, the severity of MD declined in 25 years along with the modification by age-related concomitant disorders.

keywords —— Minamata disease; temporal profile of neurological findings; multiple logistic regression analysis; discriminants; sensory disturbance

© 2005 Tohoku University Medical Press

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Address for reprints: Makoto Uchino, Department of Neurology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-0811, Japan.

e-mail: uchino96@kaiju.medic.kumamoto-u.ac.jp