Sonia Reyes

Strategic Role of Frontal White Matter Tracts in Vascular Cognitive Impairment: A Voxel-Based Lesion-Symptom Mapping Study in CADASIL.

Cerebral small vessel disease is the most common cause of vascular cognitive impairment. It typically manifests with lacunar infarcts and ischaemic white matter lesions. However, little is known about how these lesions relate to the cognitive symptoms. Previous studies have found a poor correlation between the burden of ischaemic lesions and cognitive symptoms, thus leaving much of the variance in cognitive performance unexplained. The objective of the current study was to investigate the relationship between the location of subcortical ischaemic lesions and cognitive symptoms in small vessel disease. We applied a voxel-based lesion-symptom mapping approach to data from 215 patients with CADASIL, a genetically defined small vessel disease with mutations in the NOTCH3 gene. All patients were examined by magnetic resonance imaging and comprehensive neuropsychological testing. Lacunar lesions and white matter lesions were segmented on three-dimensional T(1) and fluid-attenuated inversion recovery sequences, respectively. One hundred and forty-five subjects had a total of 854 lacunar lesions (range 1-13 per individual). The normalized volume of white matter hyperintensities ranged from 0.0425% to 21.5% of the intracranial cavity. Significant clusters for cognitive performance were detected for both lacunar lesions and white matter hyperintensities. The most prominent results were obtained on a compound score for processing speed, the predominantly affected cognitive domain in this group of patients. Strategic locations included the anterior parts of the thalamus, the genu and anterior limb of the internal capsule, the anterior corona radiata and the genu of the corpus callosum. By combining the lesion-symptom mapping data with information from a probabilistic white matter atlas we found that the majority of the processing speed clusters projected on the anterior thalamic radiation and the forceps minor. In multivariate models that included demographic parameters, brain atrophy and the volume of ischaemic lesions, regional volumes of lacunar lesions and white matter hyperintensities in the anterior thalamic radiation predicted performance in processing speed tasks, whereas there was no independent contribution of the global volume of ischaemic lesions. These observations emphasize the importance of lesion location for both lacunar and ischaemic white matter lesions. Our findings further highlight the anterior thalamic radiation as a major anatomical structure impacting on processing speed. Together these findings provide strong support for a central role of frontal-subcortical circuits in cerebral small vessel disease and vascular cognitive impairment.

Apathy: a major symptom in CADASIL.

Objective: The frequency and impact of apathy in subcortical ischemic vascular dementia (SIVD) remain undetermined. The frequency, clinical, neuropsychological, and imaging correlates of apathy were assessed in a large cohort of patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, a genetic model of SIVD. Methods: Apathy was diagnosed based on Neuropsychiatric Inventory assessment. Degree of disability was assessed by modified Rankin scale, cognitive impairment by Mattis Dementia Rating Scale (MDRS) and Mini-Mental State Examination (MMSE), autonomy by the Instrumental Activities of Daily Living (IADL) scale, and quality of life by SEP-59 self-questionnaire. Validated imaging methods were used to determine the total burden of cerebral lesions. Results: Among 132 patients, 54 (41%) were apathetic. Apathetic patients were older than nonapathetic subjects, had a lower MMSE and MDRS score, had more global disability, and were more limited in IADL. Apathetic patients were more frequently depressed compared to nonapathetic patients and more frequently presented additional neuropsychiatric symptoms. Multiple regression modeling showed a significant and independent association between apathy and a lower score of overall quality of life and between apathy and a higher load of white matter and lacunar lesions. Conclusions: The results suggest that apathy is common in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), appears in association with cognitive impairment, global functional disability, and severe neuropsychiatric symptoms during the course of the disease, and can occur separately from depression. Apathy has an independent impact on the overall quality of life in CADASIL. CADASIL = cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy; DSM-IV = Diagnostic and Statistical Manual of Mental Disorders, 4th edition; IADL = Instrumental Activities of Daily Living; ICC = intracranial cavity; LL = lacunar lesions; MDRS = Mattis Dementia Rating Scale; MMSE = Mini-Mental State Examination; mRS = modified Rankin scale; NA = not applicable because of insufficient observations; nCM = number of cerebral microhemorrhages; nLL = normalized volume of lacunar lesions; NPI = Neuropsychiatric Inventory; nWMH = normalized volume of white matter hyperintensities; QOL = quality of life; SIVD = subcortical ischemic vascular dementia; TIA = transient ischemic attack; WMH = white matter hyperintensities.Objective:The frequency and impact of apathy in subcortical ischemic vascular dementia (SIVD) remain undetermined. The frequency, clinical, neuropsychological, and imaging correlates of apathy were assessed in a large cohort of patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, a genetic model of SIVD. Methods:Apathy was diagnosed based on Neuropsychiatric Inventory assessment. Degree of disability was assessed by modified Rankin scale, cognitive impairment by Mattis Dementia Rating Scale (MDRS) and Mini-Mental State Examination (MMSE), autonomy by the Instrumental Activities of Daily Living (IADL) scale, and quality of life by SEP-59 self-questionnaire. Validated imaging methods were used to determine the total burden of cerebral lesions. Results:Among 132 patients, 54 (41%) were apathetic. Apathetic patients were older than nonapathetic subjects, had a lower MMSE and MDRS score, had more global disability, and were more limited in IADL. Apathetic patients were more frequently depressed compared to nonapathetic patients and more frequently presented additional neuropsychiatric symptoms. Multiple regression modeling showed a significant and independent association between apathy and a lower score of overall quality of life and between apathy and a higher load of white matter and lacunar lesions. Conclusions:The results suggest that apathy is common in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), appears in association with cognitive impairment, global functional disability, and severe neuropsychiatric symptoms during the course of the disease, and can occur separately from depression. Apathy has an independent impact on the overall quality of life in CADASIL. GLOSSARYCADASIL = cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy; DSM-IV = Diagnostic and Statistical Manual of Mental Disorders, 4th edition; IADL = Instrumental Activities of Daily Living; ICC = intracranial cavity; LL = lacunar lesions; MDRS = Mattis Dementia Rating Scale; MMSE = Mini-Mental State Examination; mRS = modified Rankin scale; NA = not applicable because of insufficient observations; nCM = number of cerebral microhemorrhages; nLL = normalized volume of lacunar lesions; NPI = Neuropsychiatric Inventory; nWMH = normalized volume of white matter hyperintensities; QOL = quality of life; SIVD = subcortical ischemic vascular dementia; TIA = transient ischemic attack; WMH = white matter hyperintensities.

Identification of a strategic brain network underlying processing speed deficits in vascular cognitive impairment

Patients with vascular cognitive impairment (VCI) commonly exhibit deficits in processing speed. This has been attributed to a disruption of frontal-subcortical neuronal circuits by ischemic lesions, but the exact mechanisms and underlying anatomical structures are poorly understood. We set out to identify a strategic brain network for processing speed by applying graph-based data-mining techniques to MRI lesion maps from patients with small vessel disease. We studied 235 patients with CADASIL, a genetic small vessel disease causing pure VCI. Using a probabilistic atlas in standard space we first determined the regional volumes of white matter hyperintensities (WMH) and lacunar lesions (LL) within major white matter tracts. Conditional dependencies between the regional lesion volumes and processing speed were then examined using Bayesian network analysis. Exploratory analysis identified a network of five imaging variables as the best determinant of processing speed. The network included LL in the left anterior thalamic radiation and the left cingulum as well as WMH in the left forceps minor, the left parahippocampal white matter and the left corticospinal tract. Together these variables explained 34% of the total variance in the processing speed score. Structural equation modeling confirmed the findings obtained from the Bayesian models. In summary, using graph-based models we identified a strategic brain network having the highest predictive value for processing speed in our cohort of patients with pure small vessel disease. Our findings confirm and extend previous results showing a role of frontal-subcortical neuronal circuits, in particular dorsolateral prefrontal and cingulate circuits, in VCI.

Education modifies the relation of vascular pathology to cognitive function: cognitive reserve in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy.

A clinical impact of cognitive reserve (CR) has been demonstrated in Alzheimers disease, whereas its role in vascular cognitive impairment (VCI) is largely unknown. In this study, we investigated the impact of CR in patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a genetic variant of pure VCI. A total of 247 NOTCH3 mutation carriers from a two-center study were investigated using detailed neuropsychological and neuroimaging protocols. CR was operationalized as years of formal education. Brain pathology was assessed by MRI using normalized brain volume and lacunar lesion volume as proxies. Multivariate analyses were done for each structural measure with scores of processing speed, executive function, and memory as dependent variables. Additional linear regression models were conducted with interaction terms for education × brain volume and education × lacunar lesion volume. Education had an independent impact on cognitive performance in subjects with mild and moderate degrees of brain pathology, whereas there was no significant influence of education on cognition in patients with severe MRI changes. This interaction was found for processing speed, the cognitive domain most impaired in our patients. Our findings demonstrate an interaction of education and brain pathology in regard to cognitive impairment: the effect of education seems most pronounced in early disease stages but may ultimately be overwhelmed by the pathological changes. The results extend the concept of CR to VCI.

Diagnostic Criteria of Vascular Dementia in CADASIL

Background and Purpose— Subcortical ischemic vascular dementia (SIVD) is a major subtype of vascular dementia (VaD). Recently, the diagnostic criteria of VaD have been modified to encompass this entity. Application of these criteria in CADASIL, a genetic model of SIVD, may help to better assess their significance. The aim of this study was to compare different sets of diagnostic criteria of VaD in a population of CADASIL patients. Methods— Different sets of diagnostic criteria of VaD (DSMIV, ICD10, standard NINDS-AIREN, modified NINDS-AIREN for SIVD) were applied to 115 CADASIL patients. Diagnosis of VaD was made through 2 steps: (1) diagnosis of dementia and (2) association of dementia to lesions of vascular origin. The percentage of patients satisfying the different sets and the concordance between these criteria was analyzed. Results— At least 1 set of criteria was satisfied for diagnosis in 29 subjects with dementia. In this group of patients, the sensitivity of the DSM IV, ICD 10, and standard NINDS-AIREN criteria for VaD was, respectively, 79%, 72%, and 45%. In contrast, the sensitivity of the NINDS-AIREN criteria for SIVD was 90%. The incomplete sensitivity of these last criteria was related to the absence of focal signs in some patients. The neuroimaging criteria were satisfied in all patients with dementia. Conclusions— The modified NINDS-AIREN criteria of SIVD are the most sensitive VaD criteria in CADASIL. Among these criteria, the neuroimaging criteria, although poorly specific to dementia, have a complete sensitivity. In contrast, focal signs were inconstant in CADASIL patients with dementia.

Effects of Gender on the Phenotype of CADASIL

Background and Purpose— In the general population, migraine, cerebrovascular diseases, and vascular dementia differ in many aspects between men and women. CADASIL is considered a unique model to investigate migraine with aura, stroke, and dementia related to ischemic small vessel disease. This study aims to evaluate the effect of gender on the main clinical and neuroimaging characteristics of CADASIL. Methods— Cross-sectional data from 313 CADASIL patients including various clinical and cognitive scores and MRI parameters were compared between men and women, and between those younger and older than the median age of the population corresponding to the usual age of menopause (51 years). Results— At younger than 51 years, migraine with aura was 50% more prevalent in women and stroke was 75% more prevalent in men. After the fifth decade, men had higher National Institutes of Health Stroke Scale and Rankin scores than women and more severe executive dysfunction, although global cognitive scores were similar. Age at first stroke, the number of stroke events, and the prevalence of dementia and psychiatric symptoms did not differ between men and women. Brain volume was lower in men with a trend for a larger volume of lacunar infarcts. Conclusions— In CADASIL, migraine with aura is more frequent in women and stroke is more frequent in men before the age of menopause. This difference seems to vanish after this age limit but may result in a higher degree of cognitive impairment and cerebral atrophy in men at the late stage of the disease. The presumable role of ovarian hormones in these gender-related differences remains to be explored.

Apathy is related to cortex morphology in CADASIL A sulcal-based morphometry study

Objectives: Apathy is a debilitating symptom in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), the pathophysiology of which remains poorly understood. The aim of this study was to evaluate the neuroanatomic correlates of apathy, using new MRI postprocessing methods based on the identification of cortical sulci, in a large cohort of patients with CADASIL. Methods: A total of 132 patients with genetically confirmed diagnosis were included in this prospective cohort study. Global cognitive performances were assessed by the Mattis Dementia Rating Scale (MDRS) and disability by the modified Rankin score (mRS). Apathy was defined according to standard criteria. Depth, width, and cortical thickness of 10 large sulci of the frontal lobe in each hemisphere were measured. Logistic regression modeling was used to evaluate the links between apathy and cortical thickness, depth, or width of the different sulci. All models were adjusted for age, gender, level of education, MDRS, mRS, depression, and global brain volume. Results: Complete MRI datasets of high quality were available in 119 patients. Depth of the posterior cingulate sulcus exhibited the strongest association with apathy in fully adjusted models (right: p value = 0.0006; left: p value = 0.004). Depth and width of cortical sulci in mediofrontal and orbitofrontal areas were independently associated with apathy. By contrast, cortical thickness was not. Conclusions: Cortical morphology in mediofrontal and orbitofrontal areas, by contrast to cortical thickness, is strongly and independently associated with apathy. These results suggest that apathy is related to a reduction of cortical surface rather than of cortical thickness secondary to lesion accumulation in CADASIL.

Verbal memory impairment in subcortical ischemic vascular disease A descriptive analysis in CADASIL

In the elderly, the high prevalence of Alzheimers disease neuropathology presents a major challenge to the investigation of memory decline in common diseases such as small vessel disease. CADASIL represents a unique clinical model to determine the spectrum of memory impairment in subcortical ischemic vascular dementia (SIVD). One hundred and forty CADASIL patients underwent detailed clinical, neuropsychological and imaging analyses. The Free and Cued Selective Reminding Test was used as a measure of verbal memory. Forty-four out of 140 CADASIL patients (31.4%) presented with memory impairment according to this test. Eight out of 44 (18.2%) subjects with memory impairment matched the definition of the amnestic syndrome of hippocampal type. While alterations in spontaneous recall were related to the severity of subcortical ischemic lesions, the profile of memory impairment, particularly the sensitivity to cueing was found related to other factors such as hippocampal atrophy.

Predictors of Clinical Worsening in Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy: Prospective Cohort Study

Background and Purpose— Predictors of clinical worsening in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy remain unknown. This study aims to identify demographic, clinical, and magnetic resonance imaging predictors of incident strokes, incident dementia, clinical deterioration, and death in patients with this genetically proven disease. Methods— Two hundred ninety subjects (mean age, 50.6±11.4 years) were assessed at baseline and followed up for 36 months. Incident clinical events were recorded, and clinical scores included the Mini Mental State Examination, Mattis Dementia Rating Scale, modified Rankin Scale, and Barthel index. The number of lacunes and microbleeds, the volume of white-matter hyperintensities, and brain parenchymal fraction were assessed on baseline magnetic resonance imaging. Data were analyzed by ANCOVA, multivariable logistic regression, and Cox proportional hazard models. Results— Incident stroke occurred in 55 of 278 patients (19.8%). Moderate or severe disability developed in 19 of 210 (9%) nondisabled individuals, incident dementia in 49 of 231 (20%) nondemented subjects, and 4.8% of patients died. Active smoking, the number of lacunes, and brain parenchymal fraction independently predicted incident stroke during follow-up. Gait disturbance, dementia, and brain parenchymal fraction predicted progression toward moderate or severe disability. Active smoking, disability, and brain parenchymal fraction predicted incident dementia. Age was the only significant predictor of death. Conclusions— Clinical assessment and brain magnetic resonance imaging aid in predicting incident clinical events and clinical deterioration in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy. There is a bidirectional relationship between dementia and moderate or severe disability in predicting each other’s onset. Active smoking is a modifiable risk factor associated with clinical progression in Notch3 mutation carriers.

Dilated Perivascular Spaces in Small-Vessel Disease: A Study in CADASIL

Background and Aim: Dilated perivascular spaces (dPVS) have previously been associated with aging and hypertension-related cerebral microangiopathy. However, their risk factors, radiological features and clinical relevance have been poorly evaluated in CADASIL (cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy), a unique model to investigate the pathophysiology of ischemic small-vessel disease. The purpose of this study was to investigate these different aspects in a large cohort of patients with this disorder. Methods: Demographic and MRI data of 344 patients from a prospective cohort study were analyzed. The severity of dPVS was evaluated separately in the anterior temporal lobes, subinsular areas, basal ganglia and white matter, using validated semiquantitative scales. Logistic and multiple linear regression models were used to determine the risk factors associated with the severity of dPVS in these different regions and their relationships with cognition, disability and the MRI markers of the disease (white matter hyperintensities (WMH) lacunar infarcts, microbleeds and brain parenchymal fraction (BPF)). Results: The severity of dPVS was found to increase with age regardless of cerebral area (p < 0.001). In contrast with dPVS in other locations, the severity of dPVS in the temporal lobes or subinsular areas was also found strongly and specifically related to the extent of WMH (p < 0.001). Conversely, no significant association was detected with lacunar volume, number of microbleeds or BPF. A high degree of dPVS in the white matter was associated with lower cognitive performances independently of age and other MRI markers of the disease including BPF (p ≤ 0.04). Conclusions: In CADASIL, the progression of the hereditary microangiopathy with aging may promote the dilation of perivascular spaces throughout the whole brain but with variable extent according to cerebral location. In temporal lobes and subinsular areas, dPVS are common MRI features and may share a similar pathogenesis with the extension of WMH during the course of the disease. dPVS may also participate in the development of cognitive decline in this model of small-vessel disease, and their large number in white matter may alert clinicians to a higher risk of cognitive decline in CADASIL.