White matter lesions are frequently found on cerebral MRI scans of elderly
people and are thought to be important in the pathogenesis of dementia.
Hyper tension has been associated with the presence of white matter
lesions but this has been investigated almost exclusively in
cross-sectional studies. We studied prospectively the association of these
lesions with the duration and treatment of hypertension. We randomly
sampled 1077 subjects aged between 60 and 90 years from two prospective
population-based studies. One-half of the study subjects had their blood
pressure measured between 1975 and 1978 and the other half between 1990
and 1993. All subjects underwent 1.5 T MRI scanning; white matter lesions
in the subcortical and periventricular regions were rated separately.
Subjects with hypertension had increased rates of both types of white
matter lesion. Duration of hypertension was associated with both
periventricular and subcortical white matter lesions. This relationship
was influenced strongly by age. For participants with >20 years of
hypertension and aged between 60 and 70 years at the time of follow-up,
the relative risks for subcortical and periventricular white matter
lesions were 24.3 [95% confidence interval (CI) 5.1-114.8] and 15.8 (95%
CI 3.4-73.5), respectively, compared with normotensive subjects. Subjects
with successfully treated hypertension had only moderately increased rates
of subcortical white matter lesions and periventricular white matter
lesions (relative risk 3.3, 95% CI 1.3-8.4 and 2.6, 95% CI 1.0-6.8,
respectively) compared with normotensive subjects. For poorly controlled
hypertensives, these relative risks were 8.4 (95% CI 3.1-22.6) and 5.8
(95% CI 2.1-16.0), respectively. In conclusion, we found a relationship
between long-standing hypertension and the presence of white matter
lesions. Our findings are consistent with the view that effective
treatment may reduce the rates of both types of white matter lesion.
Adequate treatment of hypertension may therefore prevent white matter
lesions and the associated cognitive decline.