Matthijs Oudkerk

Prevalence of cerebral white matter lesions in elderly people: a population based magnetic resonance imaging study. The Rotterdam Scan Study

OBJECTIVE White matter lesions are often seen on MR scans of elderly non-demented and demented people. They are attributed to degenerative changes of small vessels and are implicated in the pathogenesis of cognitive decline and dementia. There is evidence that especially periventricular white matter lesions are related to cognitive decline, whereas subcortical white matter lesions may be related to late onset depression. The frequency distribution of subcortical and periventricular white matter lesions according to age and sex reported. METHODS A total of 1077 subjects aged between 60–90 years were randomly sampled from the general population. All subjects underwent 1.5T MR scanning; white matter lesions were rated separately for the subcortical region and the periventricular region. RESULTS Of all subjects 8% were completely free of subcortical white matter lesions, 20% had no periventricular white matter lesions, and 5% had no white matter lesions in either of these locations. The proportion with white matter lesions increased with age, similarly for men and women. Women tended to have more subcortical white matter lesions than men (total volume 1.45 ml v 1.29 ml; p=0.33), mainly caused by marked differences in the frontal white matter lesion volume (0.89 ml v 0.70 ml; p=0.08). Periventricular white matter lesions were also more frequent among women than men (mean grade 2.5 v 2.3; p=0.07). Also severe degrees of subcortical white matter lesions were more common in women than in men (OR 1.1; 95% confidence interval (95% CI) 0.8–1.5) and periventricular white matter lesions (OR 1.2; 95% CI 0.9–1.7), albeit that none of these findings were statistically significant. CONCLUSIONS The prevalence and the degree of cerebral white matter lesions increased with age. Women tended to have a higher degree of white matter lesions than men. This may underlie the finding of a higher incidence of dementia in women than in men, particularly at later age.

Incidence and Risk Factors of Silent Brain Infarcts in the Population-Based Rotterdam Scan Study

Background and Purpose— The prevalence of silent brain infarcts in healthy elderly people is high, and these lesions are associated with an increased risk of stroke. The incidence of silent brain infarcts is unknown. We investigated the incidence and cardiovascular risk factors for silent brain infarcts. Methods— The Rotterdam Scan Study is a prospective, population-based cohort study of 1077 participants 60 to 90 years of age. All participants underwent cranial MRI in 1995 to 1996, and 668 participants had a second MRI in 1999 to 2000 (response rate, 70%) with a mean interval of 3.4 years. We assessed cardiovascular risk factors by interview and physical examination at baseline. Associations between risk factors and incident silent infarcts were analyzed by multiple logistic regression. Results— Ninety-three participants (14%) had ≥1 new infarcts on the second MRI; of these, 81 had only silent and 12 had symptomatic infarcts. The incidence of silent brain infarcts strongly increased with age and was 5 times higher than that of symptomatic stroke. A prevalent silent brain infarct strongly predicted a new silent infarct on the second MRI (age- and sex-adjusted odds ratio, 2.9; 95% confidence interval, 1.7 to 5.0). Age, blood pressure, diabetes mellitus, cholesterol and homocysteine levels, intima-media thickness, carotid plaques, and smoking were associated with new silent brain infarcts in participants without prevalent infarcts. Conclusions— The incidence of silent brain infarcts on MRI in the general elderly population strongly increases with age. The cardiovascular risk factors for silent brain infarcts are similar to those for stroke.

Coronary Calcification Improves Cardiovascular Risk Prediction in the Elderly

Background—Coronary calcification detected by electron beam tomography may improve cardiovascular risk prediction. The technique is particularly promising in the elderly because the predictive power of cardiovascular risk factors weakens with age. We investigated the prognostic value of coronary calcification for cardiovascular events and mortality in a general, asymptomatic population of elderly subjects. Methods and Results—From 1997 to 2000, electron beam tomography scanning to assess coronary calcification was performed in subjects of the population-based Rotterdam Study. Risk factors were measured by standardized procedures. Coronary calcium scores were available for 1795 asymptomatic participants (mean age, 71 years; range, 62 to 85 years). During a mean follow-up of 3.3 years, 88 cardiovascular events, including 50 coronary events, occurred. The risk of coronary heart disease increased with increasing calcium score. The multivariate-adjusted relative risk of coronary events was 3.1 (95% CI, 1.2 to 7.9) for calcium scores of 101 to 400, 4.6 (95% CI, 1.8 to 11.8) for calcium scores of 401 to 1000, and 8.3 (95% CI, 3.3 to 21.1) for calcium scores >1000 compared with calcium scores of 0 to 100. The predictive value in subjects >70 years of age was similar. Risk prediction based on the cardiovascular risk factors improved when coronary calcification was added. Conclusions—Coronary calcification is a strong and independent predictor of coronary heart disease, also in the elderly. Coronary calcification improves prediction of coronary events based on cardiovascular risk factors. Risk stratification by assessment of coronary calcification may have an important role in the primary prevention of coronary heart disease events in the elderly.

Cerebral white matter lesions and subjective cognitive dysfunction: The Rotterdam Scan Study

Objective: To determine the relationship between cerebral white matter lesions (WML) and subjective cognitive dysfunction. Background: Subjective cognitive dysfunction is present when a person perceives failures of cognitive function. When annoying enough, these failures will be expressed as complaints. Subjective cognitive dysfunction may be a prelude to or coincide with objective cognitive impairment. WML have been related to objective cognitive impairment and dementia, but their relationship with subjective cognitive dysfunction is not clear. Previous population-based studies on the latter relationship have been limited in sample size, recording of subjective cognitive function, and assessment of WML severity. Methods: We randomly sampled 1,049 elderly nondemented participants from the general population. Data on subjective cognitive dysfunction and its progression were derived from a 15-item questionnaire. Objective cognitive performance was assessed using a series of neuropsychological tests. WML were scored on MRI for periventricular and subcortical regions separately. Results: WML were associated with more subjective cognitive failures. WML were more severe for participants reporting progression of these failures compared with participants without these failures, especially within participants with better than average cognitive performance (p = 0.008, for periventricular WML). Participants with severe WML reported progression of cognitive failures more than twice as often than did those with little or no WML. The relationship between the severity of WML and subjective cognitive failures was present for periventricular and subcortical WML. Conclusions: WML are associated with subjective cognitive failures and in particular with reporting progression of these failures, even in the absence of objective cognitive impairment.

A follow-up study of blood pressure and cerebral white matter lesions.

White matter lesions are often observed on cerebral magnetic resonance imaging scans of elderly people and may play a role in the pathogenesis of dementia. Cross‐sectional studies have shown an association between elevated blood pressure and white matter lesions. We prospectively studied the relation between blood pressure and white matter lesions in 1,077 subjects aged 60 to 90 years who were randomly sampled from two prospective population‐based studies. One study had blood pressure measurements 20 years before, the other 5 years before. Overall response for the magnetic resonance imaging study was 63%, and declined from 73% among 60‐ to 70‐year‐olds to 48% for 80‐ to 90‐year‐olds. Diastolic and systolic blood pressure levels assessed 20 years before were significantly associated with subcortical and periventricular white matter lesions. The association between 20‐year change in diastolic blood pressure and subcortical white matter lesions was J‐shaped (relative risk, 2.2; 95% confidence interval, 1.0–5.2; and relative risk, 3.2; 95% confidence interval, 1.4–7.4, for decrease or increase of more than 10 mm Hg, respectively). The association between concurrent diastolic blood pressure level and white matter lesions was linear in subjects without, and J‐shaped in subjects with, a history of myocardial infarction. Our results indicate that the J‐shape relationship of diastolic blood pressure is not restricted to cardiovascular disease, but is also manifest in cerebrovascular disease.

Hippocampal head size associated with verbal memory performance in nondemented elderly

The hippocampus plays a crucial role in the consolidation of memory. Anatomically, the hippocampal head, body, and tail are connected to separate regions of the entorhinal cortex, which conveys processed information from the association cortices to the hippocampus. Little is known, however, about the functional segregation along its longitudinal axis. In the present study, we investigated whether the hippocampal head, body, or tail is selectively involved in verbal memory performance. A total of 511 nondemented participants, aged 60-90 years, underwent a three-dimensional HASTE brain scan in a 1.5-T MRI unit. Hippocampal volumes were measured by manual tracing on coronal slices. Segmentation was performed in anterior-posterior direction on the basis of predefined cutoffs allocating 35, 45, and 20% of slices to the head, body, and tail, respectively. Memory performance was assessed by a 15-word learning test including tasks of immediate and delayed recall. To analyze the association between head, body, and tail volumes and memory performance, we used multiple linear regression, adjusting for age, sex, education, and midsagittal area as a proxy for intracranial volume. Participants with larger hippocampal heads scored significantly higher in the memory test, most notably in delayed recall (0.41 word per SD increase in left hippocampal head (95% CI (0.16, 0.67)), 0.33 word per SD increase in right hippocampal head (95% CI 0.06, 0.59)). Our data suggest selective involvement of the hippocampal head in verbal memory, and add to recent findings of functional segregation along the longitudinal axis of the hippocampus.

Carotid atherosclerosis and cerebral white matter lesions in a population based magnetic resonance imaging study

Abstract Cerebral white matter lesions are frequently observed on magnetic resonance imaging of elderly, nondemented persons. There is evidence that white matter lesions are involved in the pathophysiology of cognitive decline and dementia. White matter lesions can be divided into those in the periventricular and those in the subcortical region. Pathological and epidemiological studies suggest that atherosclerosis is involved in the pathogenesis of these lesions. Our study reports on the association between atherosclerosis in the carotid arteries and white matter lesions in a population-based study among 1077 elderly subjects. We randomly sampled 1077 subjects aged between 60–90 years from two prospective population-based studies. All subjects underwent ultrasonography of the carotid artery. In addition, 1.5 T magnetic resonance imaging was performed; white matter lesions in the subcortical and periventricular regions were rated separately. With increasing number of plaques in the carotid artery the severity of periventricular white matter lesions increased (Ptrend = 0.03), but not the severity of subcortical white matter lesions (Ptrend = 0.19). In addition, an increase in intima media thickness was borderline significantly associated with an increased severity of periventricular white matter lesions (Ptrend = 0.09), but not of subcortical white matter lesions (Ptrend = 0.68). These findings suggest that partly dissimilar pathogenetic mechanisms are involved in the etiology of periventricular and subcortical white matter lesions.

Aortic Atherosclerosis at Middle Age Predicts Cerebral White Matter Lesions in the Elderly

BACKGROUND AND PURPOSE MRI scans of the brains of elderly people frequently show white matter lesions. Clinically, these lesions are associated with cognitive impairment and dementia. A relation between atherosclerosis and white matter lesions was found in some small cross-sectional studies. However, atherosclerosis is a gradual process that starts early in life. We investigated the longitudinal association between aortic atherosclerosis assessed during midlife and late life and cerebral white matter lesions. METHODS We randomly sampled subjects between 60 and 90 years old from 2 population-based follow-up studies in which subjects had their baseline examinations in 1975 to 1978 (midlife) and in 1990 to 1993 (late life). In 1995 to 1996, subjects underwent 1.5-T MRI scanning; white matter lesions were rated in the deep subcortical and periventricular regions separately. Aortic atherosclerosis was assessed on abdominal radiographs that were obtained from 276 subjects in midlife and 531 subjects in late life. RESULTS The presence of aortic atherosclerosis during midlife was significantly associated with the presence of periventricular white matter lesions approximately 20 years later (adjusted relative risk, 2.4; 95% CI, 1.2 to 5.0); the relative risks increased linearly with the severity of aortic atherosclerosis. No association was found between midlife aortic atherosclerosis and subcortical white matter lesions (adjusted relative risk, 1.1; 95% CI, 0.5 to 2.3) or between late-life aortic atherosclerosis and white matter lesions. CONCLUSIONS The pathogenetic process that leads to cerebral periventricular white matter lesions starts already in or before midlife. The critical period for intervention directed at prevention of white matter lesions and its cognitive consequences may be long before these lesions become clinically detectable.

Atrial fibrillation and the risk of cerebral white matter lesions

Background: Cerebral white matter lesions are often observed on MRI scans of elderly nondemented and demented persons. Their pathogenesis is not fully understood but cerebral hypoperfusion may be involved. Atrial fibrillation is a common finding in elderly subjects and may lead to a reduced cardiac output with cerebral hypoperfusion. The authors investigated the association between atrial fibrillation and the presence of white matter lesions. Methods: From 1995 through 1996, the authors randomly sampled 1077 subjects from two ongoing prospective population-based studies. From each participant, an electrocardiogram (ECG) was recorded; atrial fibrillation and left ventricular hypertrophy were diagnosed with a computer program. For one of the two groups (553 subjects), earlier ECGs were available (mean follow-up 4.7 years). All subjects underwent 1.5-T MRI scanning; white matter lesions were separately rated for the periventricular and subcortical regions. Results: The prevalence of atrial fibrillation was 1.9% among subjects younger than 75 years and 5.5% in subjects older than 75 years. The total number of subjects with atrial fibrillation was 28. Subjects with atrial fibrillation had severe periventricular white matter lesions more than twice as often as subjects who did not (RR 2.2; 95% CI 1.0 to 5.2) but had no increased risk of subcortical white matter lesions (RR 1.1; 95% CI 0.4 to 2.6). For seven subjects with atrial fibrillation both at baseline and at follow up, these relative risks were 6.3 (95% CI 1.1 to 37.1) and 0.7 (95% CI 0.1 to 3.7). Conclusions: Atrial fibrillation is associated with periventricular white matter lesions, but not with subcortical white matter lesions.

CASCADE: A European Collaborative Study on Vascular Determinants of Brain Lesions

Dementia is a highly prevalent disease that may have a cardiovascular component. White matter lesions and brain atrophy (brain abnormalities) are prevalent in dementia cases and might form part of the anatomical basis for the disease. We designed a multi-centre study, CASCADE (Cardiovascular Determinants of Dementia), to examine long-term (10–20 years) and short-term (5 years) cardiovascular risk factors for, and the cognitive consequence of, brain abnormalities. White matter lesions and atrophy are measured with magnetic resonance imaging. Cognitive function is measured with nine tests of memory and executive function. The studies included in CASCADE were ongoing and geographically spread throughout Europe to capture the cardiovascular risk gradient. In each study, a random sample of at least 100 subjects aged 65–75 years was selected who participated in the previous research examinations conducted by the respective centres. The objectives and design of the CASCADE project are described.