Cerebral small-vessel disease and decline in information processing speed, executive function and memory
Prins ND, van Dijk EJ, den Heijer T, Vermeer SE, et al. ;
Commented by , 23 Oct 2005
Aim of the study
Evaluate the relationship between measures of cerebral small-vessel disease on MRI and the rate of decline on cognition.
Method
Participants from a prospective population-based study in Rotterdam, age 60 to 90 and free from dementia at baseline, had a MRI, examined for white matter lesions (WML), cerebral infarcts and generalized brain atrophy. Neuropsychological tests were repeated over time, including
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the MMSE
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Stroop test
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Letter-Digit Substitution Task
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a verbal fluency test (animal categories)
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a 15-word verbal learning test
Compound scores were used for global cognitive function (or cognitive index) using the average of the z scores (individual test score minus mean test score divided by standard deviation). Random-effects models for repeated measures were used to test the association between MRI findings and cognitive changes.
Results
2266 assessments were done on the 832 participants, with an average time of 5.2 years from first to last assessment. The mean annual decline on the cognitive index was 0.022 (95% confidence interval 0.029-0.014) and on the MMSE 0.031 (95% confidence interval 0.057-0.005).
Increasing severity of periventricular WML and generalized brain atrophy and the presence of cerebral infarcts on MRI at baseline were associated with a steeper decline in cognitive function, particularly for information processing speed and executive function.
None of the MRI measures were associated with a decline in the verbal learning test; 42 participants had a stroke and 23 developed dementia during follow-up.
Professor Gauthier's comments
This study confirms that small-vessel disease causing structural brain changes on MRI is associated with a faster rate of decline in cognitive function, specifically those associated with speed of information processing and executive function.
Small-vessel disease is common and risk factors have been clearly identified, such as mid-life systolic hypertension (recently reviewed by C. Qiu, B. Winblad and L. Fratiglioni).
All adults should monitor their blood pressure at certain intervals and labile or sustained hypertension should be treated over a life-time as a mean to prevent vascular cognitive impairment and possibly delaying the onset of Alzheimer’s disease.
The authors of this article should be congratulated not only for the rigor of their methods and analysis but also for the extreme clarity of their text.