Katja Petrovic

White matter lesion progression, brain atrophy, and cognitive decline : The Austrian stroke prevention study

White matter lesions progress over time, but the clinical consequences are widely unknown. Three‐hundred twenty‐nine elderly community‐dwelling volunteers underwent serial magnetic resonance imaging scanning and cognitive testing at baseline and at 3‐ and 6‐year follow‐up. We measured the changes in white matter lesion and brain parenchymal volumes. After 6 years, the median increase in white matter lesion load was 0.2cm3 (interquartile range [IQR], 0.0–0.80cm3) with a maximum of 31.4cm3. The median loss of brain volume was 2.3% (IQR, 1.13–3.58%). Increasing white matter lesion volume was correlated with loss of brain volume (p < 0.0001) and performance decline in tests of memory (p = 0.022), conceptualization (p = 0.046), and visuopractical skills (p = 0.005). Associations between changes in white matter lesion load and cognitive functioning were no longer significant when adding change in brain volume to the models, suggesting that cognitive decline related directly to loss of brain substance with progression of lesion burden. Ann Neurol 2005;58:610–616

White Matter Hyperintensities Rather Than Lacunar Infarcts Are Associated With Depressive Symptoms in Older People: The LADIS Study

OBJECTIVE Both white matter hyperintensities (WMH) and lacunar infarcts have been associated with the development of depression in older subjects, although the relative importance of the two and the influence of lesion location and concomitant vascular disease are unclear. This study investigates the relationship between location and burden of WMH and lacunes on depressive features in older people. METHOD In a pan-European multicenter study of 626 older subjects, the authors examined the relationship between regional magnetic resonance imaging white matter hyperintensities, number of lacunar infarcts, depressive symptoms as assessed by the 15-item geriatric depression scale (GDS), cognitive status (Mini-Mental Status Examination), hypertension, and self-perceived health quality of life (QoL). RESULTS The authors found depressive symptoms to be correlated with WMH rating in the frontal (N=626; Spearmans rho=0.161, p <0.001) and temporal (rho=0.14, p <0.001) but not occipitoparietal region (rho=0.07, p=0.07). Basal ganglia lacunes were only weakly correlated with GDS (rho=0.09, p=0.03), and lacunes in other regions showed no association. In a ordinal logistic regression model (controlling for QoL, Mini-Mental Status Examination, age, and with an interaction between WMH and hypertension), temporal WMH in the absence of hypertension independently predicted GDS, whereas neither history of stroke nor number of lacunar infarcts did. The authors compared left- versus right-sided WMH and found no effect of laterality on depressive symptoms. CONCLUSIONS The results suggest that in this population of nondisabled older people, WMH have a greater influence on depressive symptoms than infarcts.

Progression of Leukoaraiosis and Cognition

Background and Purpose— Leukoaraiosis is used interchangeably with the term white matter lesions on MRI and seen to some degree in more than half of the routine scans in older persons. Clinicians often struggle to explain the implications of these findings to their patients. Recent data on the progression rate of ischemic white matter damage and its cognitive consequences may help in patient counseling and have implications on treatment trials in vascular cognitive impairment. Summary of Review— Leukoaraiosis progresses over time. Its extent at baseline is an important predictor for the subsequent rate of lesion progression. Subjects with punctate abnormalities on MRI have a low tendency for progression, individuals with early confluent and confluent changes tend to progress rapidly. Differences in measurement methods and cohort composition make it difficult to compare progression rates reported by different studies. Nevertheless, in community-dwelling cohorts, white matter lesions volume increased by as much as one quarter per year in subjects with confluent abnormalities at baseline. Progression of leukoaraiosis relates to cognitive decline, but this association is complex and modulated by other morphological factors like brain atrophy. Conclusions— Evidence for rapid progression of widespread leukoaraiosis and the associated cognitive decline in domains particularly affected by cerebral small vessel disease has set the stage for exploratory clinical trials in vascular cognitive impairment using white matter lesions progression as a surrogate marker.

Genome-wide association studies of cerebral white matter lesion burden

White matter hyperintensities (WMHs) detectable by magnetic resonance imaging are part of the spectrum of vascular injury associated with aging of the brain and are thought to reflect ischemic damage to the small deep cerebral vessels. WMHs are associated with an increased risk of cognitive and motor dysfunction, dementia, depression, and stroke. Despite a significant heritability, few genetic loci influencing WMH burden have been identified.

Determinants of brain iron in multiple sclerosis A quantitative 3T MRI study

Objectives: Abnormal high cerebral iron deposition may be implicated in chronic neurologic disorders, including multiple sclerosis (MS). R2* relaxometry has been recently validated in a postmortem study to indicate brain iron accumulation in a quantitative manner. We used this technique to assess brain iron levels in different stages of MS and healthy controls (HC) and determined their relation with demographic, clinical, neuropsychological, and other imaging variables. Methods: We studied 113 consecutive patients (35 clinically isolated syndrome [CIS], 78 MS) and 35 HC with 3 T MRI and clinical and neuropsychological examination. Iron deposition in subcortical gray matter structures was assessed by automated, regional calculation of R2* rates. Results: Basal ganglia (BG) R2* levels were significantly increased in MS compared to CIS (p < 0.001) and HC (p < 0.005). They were correlated with age (r = 0.5, p < 0.001), disease duration (r = 0.5, p < 0.001), Expanded Disability Status Scale (r = 0.3, p < 0.005), and the z values of mental processing speed (r = −0.3, p < 0.01). Stepwise linear regression analysis revealed gray matter atrophy as the strongest independent predictor of BG R2* levels (p < 0.001), followed by age (p < 0.001) and T2 lesion load (p < 0.005). Conclusion: BG iron accumulation in MS occurs with advancing disease and is related to the extent of morphologic brain damage, which argues for iron deposition as an epiphenomenon. The absence of increased iron levels in patients with CIS indicates that iron accumulation does not precede the development of MS.

Diffusion-Weighted Imaging and Cognition in the Leukoariosis and Disability in the Elderly Study

Background and Purpose— The mechanisms by which leukoariosis impacts on clinical and cognitive functions are not yet fully understood. We hypothesized that ultrastructural abnormalities of the normal-appearing brain tissue (NABT) assessed by diffusion-weighted imaging played a major and independent role. Methods— In addition to a comprehensive clinical, neuropsychologic, and imaging work-up, diffusion-weighted imaging was performed in 340 participants of the multicenter leukoariosis and disability study examining the impact of white matter hyperintensities (WMH) on 65- to 85-year old individuals without previous disability. WMH severity was rated according to the Fazekas score. Multivariate regression analysis served to assess correlations of histogram metrics of the apparent diffusion coefficient (ADC) of whole-brain tissue, NABT, and of the mean ADC of WMH with cognitive functions. Results— Increasing WMH scores were associated with a higher frequency of hypertension, a greater WMH volume, more brain atrophy, worse overall cognitive performance, and changes in ADC. We found strong associations between the peak height of the ADC histogram of whole-brain tissue and NABT with memory performance, executive dysfunction, and speed, which remained after adjustment for WMH lesion volume and brain atrophy and were consistent among centers. No such association was seen with the mean ADC of WMH. Conclusions— Ultrastructural abnormalities of NABT increase with WMH severity and have a strong and independent effect on cognitive functions, whereas diffusion-weighted imaging metrics within WMH have no direct impact. This should be considered when defining outcome measures for trials that attempt to ameliorate the consequences of WMH progression.

C-Reactive Protein, Carotid Atherosclerosis, and Cerebral Small-Vessel Disease Results of the Austrian Stroke Prevention Study

Background and Purpose— C-reactive protein (CRP) is an inflammatory marker known to be a risk factor for stroke. We examined the associations between CRP, carotid atherosclerosis, white matter lesions, and lacunes as manifestations of cerebral large- and small-vessel disease. Methods— In the community-based Austrian Stroke Prevention Study, CRP concentrations were measured by a highly sensitive assay in 700 participants at baseline. All underwent carotid duplex scanning, and a subset of 505 subjects underwent brain magnetic resonance imaging. Imaging was repeated after 3 and 6 years. We graded carotid atherosclerosis in both common and internal carotid arteries on a 5-point scale and calculated the sum of scores as an index of the severity of carotid atherosclerosis. The volume of white matter lesions and the number of lacunes were considered small vessel disease–related brain abnormalities. Results— After adjustment for vascular risk factors, the severity and progression of extracranial carotid atherosclerosis increased with increasing quintiles of CRP. Only study participants in the fourth and fifth quintile (>2.50 mg/L) had significantly more baseline atherosclerosis and greater progression when we used the first quintile (<0.80 mg/L) as a reference. No interactions were seen between CRP quintiles and vascular risk factors for carotid atherosclerosis. The associations between severity and progression of small vessel disease–related brain abnormalities and CRP were nonsignificant. Conclusions— We found evidence for differential effects of CRP in different beds of the arterial brain supply. CRP was a marker for active carotid atherosclerosis but not for small vessel disease–related brain lesions.

Genetic variants of the NOTCH3 gene in the elderly and magnetic resonance imaging correlates of age-related cerebral small vessel disease

Cerebral small vessel disease-related brain lesions such as white matter lesions and lacunes are common findings of magnetic resonance imaging in the elderly. These lesions are thought to be major contributors to disability in old age, and risk factors that include age and hypertension have been established. The radiological, histopathologic and clinical phenotypes of age-related cerebral small vessel disease remarkably resemble autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy, which is caused by mutations in NOTCH3. We hypothesized that genetic variations in NOTCH3 also play a role in age-related cerebral small vessel disease. We directly sequenced all 33 exons, the promoter and 3′-untranslated region of NOTCH3 in 195 participants with either coalescent white matter lesions or lacunes and compared the results to 82 randomly selected participants with no focal changes on magnetic resonance images in the Austrian Stroke Prevention Study. We detected nine common and 33 rare single nucleotide polymorphisms, of which 20 were novel. All common single nucleotide polymorphisms were genotyped in the entire cohort (n = 888), and four of them, rs1043994, rs10404382, rs10423702 and rs1043997, were associated significantly with both the presence and progression of white matter lesions. The association was confined to hypertensives, a result which we replicated in the Cohorts for Heart and Ageing Research in Genomic Epidemiology Consortium on an independent sample of 4773 stroke-free hypertensive elderly individuals of European descent (P = 0.04). The 33 rare single nucleotide polymorphisms were scattered over the NOTCH3 gene with three being located in the promoter region, 24 in exons (18 non-synonymous), three in introns and three in the 3′-untranslated region. None of the single nucleotide polymorphisms affected a cysteine residue. Sorting Intolerant From Tolerant, PolyPhen2 analyses and protein structure simulation consistently predicted six of the non-synonymous single nucleotide polymorphisms (H170R, P496L, V1183M, L1518M, D1823N and V1952M) to be functional, with four being exclusively or mainly detected in subjects with severe white matter lesions. In four individuals with rare non-synonymous single nucleotide polymorphisms, we noted anterior temporal lobe hyperintensity, hyperintensity in the external capsule, lacunar infarcts or subcortical lacunar lesions. None of the observed abnormalities were specific to cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy. This is the first comprehensive study investigating (i) the frequency of NOTCH3 variations in community-dwelling elderly and (ii) their effect on cerebral small vessel disease related magnetic resonance imaging phenotypes. We show that the NOTCH3 gene is highly variable with both common and rare single nucleotide polymorphisms spreading across the gene, and that common variants at the NOTCH3 gene increase the risk of age-related white matter lesions in hypertensives. Additional investigations are required to explore the biological mechanisms underlying the observed association.

Reorganization in cognitive networks with progression of multiple sclerosis Insights from fMRI

Objectives: Cognitive dysfunction (CD) is frequent in multiple sclerosis (MS) and can occur at early stages. Whereas functional reorganization with disease progression has been described for the motor system in MS using fMRI, no such studies exist for cognition. We attempted to assess the concept of functional reorganization concerning cognition using a simple “Go/No-go” fMRI paradigm. Methods: Patients with a clinically isolated syndrome (CIS, n = 10), relapsing-remitting MS (RRMS) (n = 10), or secondary progressive MS (SPMS) (n = 10), and 28 healthy controls (HC), underwent a comprehensive neuropsychological test battery, clinical examination, structural imaging, and an fMRI Go/No-go discrimination task at 3 T. Results: Patients performed worse than HC regarding memory, sustained attention and concentration, and information processing. These differences were driven by patients with SPMS. The fMRI task elicited activation in a widespread network including bilateral mesial and dorsolateral frontal, parietal, insular, basal ganglia, and cerebellar regions. Task performance was similar between phenotypes, but deviation from the activation pattern observed in HC and patients with CIS increased with disease progression. Patients with RRMS showed increased brain activation in the precuneus, both superior parietal lobes, and the right fusiform gyrus, and recruited the hippocampus with increasing demands. Patients with SPMS demonstrated the most abnormal network function, including recruitment of pre-SMA, bilateral superior and inferior parietal, dorsolateral prefrontal, right precentral, bilateral postcentral, and right temporal brain areas. Conclusion: Using a cognitive fMRI paradigm, we were able to confirm adaptive changes of neuronal activation with progressing MS and to provide strong evidence for their compensatory nature, at least partially.

Metabolic Syndrome, Brain Magnetic Resonance Imaging, and Cognition

OBJECTIVE We explored cognitive impairment in metabolic syndrome in relation to brain magnetic resonance imaging (MRI) findings. RESEARCH DESIGN AND METHODS We studied 819 participants free of clinical stroke and dementia of the population-based Austrian Stroke Prevention Study who had undergone brain MRI, neuropsychological testing, and a risk factor assessment relevant to National Cholesterol Education Program Adult Treatment Panel III criteria–defined metabolic syndrome. High-sensitivity C-reactive protein (hs-CRP) was also determined. RESULTS Of 819 subjects, 232 (28.3%) had metabolic syndrome. They performed worse than those without metabolic syndrome on cognitive tests assessing memory and executive functioning after adjustment for possible confounders. Stratification by sex demonstrated that metabolic syndrome was related to cognitive dysfunction in men but not in women. Only in men was an increasing number of metabolic syndrome components associated with worse cognitive performance. MRI showed no significant differences in focal ischemic lesions and brain volume between subjects with and without metabolic syndrome, and MRI abnormalities failed to explain impaired cognition. Cognitive performance was most affected in male subjects with metabolic syndrome who also had high hs-CRP levels. CONCLUSIONS Metabolic syndrome exerts detrimental effects on memory and executive functioning in community-dwelling subjects who have not had a clinical stroke or do not have dementia. Men are more affected than women, particularly if they have high inflammatory markers. MRI-detected brain abnormalities do not play a crucial role in these relationships.