Emergence and progress of white matter lesion in brain check-up.

White matter lesion (WML) is thought to emerge and progress with increasing age but has not yet been well investigated. In this study of WML, risk factors and prevalence added to emergence rate (%/person year) and progress speed [increase of leukoencephalopathy score (LES)/person year] were investigated in 1674 brain check-up subjects from August 1993 to August 2001. Significant (P < 0.01) risk factors were aging and hypertension. Prevalence rate (%) was 0 in 20-29 years, 1.4 in 30-39 years, 4.2 in 40-49 years, 20.9 in 50-59 years, 42.6 in 60-69 years, and 73.9 in 70-years. Emergence rate was 0 in 20-29 years, 0.7 in 30-39 years, 1.5 in 40-49 years, 3.4 in 50-59 years, 6.0 in 60-69 years, and 20 in 70-years. And progress speed was 0.12 in 40-49 years, 0.15 in 50-59 years, 0.21 in 60-69 years, and 0.21 in 70-years. WML begins to emerge early in middle age and both prevalence and severity increase with age.