Association of Mitochondrial DNA Copy Number With Brain MRI Markers and Cognitive Function: A Meta-analysis of Community-Based Cohorts

BACKGROUND AND OBJECTIVES

Previous studies suggest that lower mitochondrial DNA (mtDNA) copy number (CN) is associated with neurodegenerative diseases. However, whether mtDNA CN in whole blood is related to endophenotypes of Alzheimer disease (AD) and AD-related dementia (AD/ADRD) needs further investigation. We assessed the association of mtDNA CN with cognitive function and MRI measures in community-based samples of middle-aged to older adults.

METHODS

We included dementia-free participants from 9 diverse community-based cohorts with whole-genome sequencing in the Trans-Omics for Precision Medicine (TOPMed) program. Circulating mtDNA CN was estimated as twice the ratio of the average coverage of mtDNA to nuclear DNA. Brain MRI markers included total brain, hippocampal, and white matter hyperintensity volumes. General cognitive function was derived from distinct cognitive domains. We performed cohort-specific association analyses of mtDNA CN with AD/ADRD endophenotypes assessed within ±5 years (i.e., cross-sectional analyses) or 5-20 years after blood draw (i.e., prospective analyses) adjusting for potential confounders. We further explored associations stratified by sex and age (<60 vs ≥60 years). Fixed-effects or sample size-weighted meta-analyses were performed to combine results. Finally, we performed mendelian randomization (MR) analyses to assess causality.

RESULTS

We included up to 19,152 participants (mean age 59 years, 57% women). Higher mtDNA CN was cross-sectionally associated with better general cognitive function (β = 0.04; 95% CI 0.02-0.06) independent of age, sex, batch effects, race/ethnicity, time between blood draw and cognitive evaluation, cohort-specific variables, and education. Additional adjustment for blood cell counts or cardiometabolic traits led to slightly attenuated results. We observed similar significant associations with cognition in prospective analyses, although of reduced magnitude. We found no significant associations between mtDNA CN and brain MRI measures in meta-analyses. MR analyses did not reveal a causal relation between mtDNA CN in blood and cognition.

DISCUSSION

Higher mtDNA CN in blood is associated with better current and future general cognitive function in large and diverse communities across the United States. Although MR analyses did not support a causal role, additional research is needed to assess causality. Circulating mtDNA CN could serve nevertheless as a biomarker of current and future cognitive function in the community.

Abstract P103: Associations Between Brain Volumes and Cerebral Blood Flow and Sex Hormones in the Look AHEAD Brain MRI Cohort

Background: Females have greater relative brain volume (BV) and cerebral blood flow (CBF) compared to males. BV decreases after menopause suggesting a possible role of sex hormones. We studied the association of BV, abnormal white matter hyperintensity volumes (WMHV) and cerebral blood flow (CBF) with sex hormones in adults with type 2 diabetes (T2DM), which is associated with risk of brain atrophy.

Methods: The sample was 215 participants with overweight or obesity and T2DM from the Look AHEAD Brain MRI cohort (mean age 68 years [SD: 6.3], 27% male, 73% female [all postmenopausal]; without exogenous hormones), who had brain MRIs to evaluate their total BV, WMHV and CBF. The ratio of brain measurements to intracranial volume was analyzed to account for body size. Estradiol (E2) and testosterone levels (T) were estimated with electrochemoluminescence assays. In females, who have low E2 and T levels, we compared brain measures in those with detectable (vs. undetectable) hormone levels (E2<20 pg/mL, 79%; T<0.02 pg/mL, 37%). In males, we used Spearman correlation to assess the association between brain measures and sex hormone levels. The associations between BV, WMHV and E2 and T were adjusted for age and BMI using linear regression.

Results: Females with detectable (vs. undetectable) T levels had higher BV (p=0.04) (Table), which was attenuated after adjustment for age and BMI. WMHV and CBF were not statistically associated with sex hormone levels in females. In males, no brain measures were significantly associated with sex hormones levels.

Conclusions: In postmenopausal females with T2DM, detectable levels of T were associated greater BV, but not associated any CBF or WMHV. In males, none of the brain measures were associated with sex hormones. Our findings are limited by a small, convenient sample size and low sensitivity of hormone assays with a high proportion of undetectable levels. Our findings suggest that larger samples with high sensitivity hormone assays are needed to assess clinically important differences.

Abstract WP121: Can The Extended Glasgow Outcome Scale (e-gos) Augment The Interpretation Of Results From Clinical Trials Of Minimally Invasive Surgery Of Spontaneous Intracerebral Hemorrhage Using The Modified Rankin Scale (mrs): A Secondary Analysis Of The Clear-iii And Mistie-iii Trials

Introduction: Currently, the modified Rankin scale (mRS) is most commonly used to assess functional outcome in clinical trials of interventions for spontaneous intracerebral hemorrhage (ICH). Extended Glasgow Outcome Score (eGOS) is often used to assess global disability/recovery after traumatic brain injury and provides additional discrimination of vegetative state (VS) from lower severe disability (LSD). We compared primary outcomes from 2 clinical trials of minimally invasive surgery for intracerebral and intraventricular hemorrhage (ICH/IVH) at different thresholds of eGOS.

Methods: Post-hoc analysis of primary outcomes (PO) from the CLEAR-III trial (intraventricular alteplase [IVtPA] vs. saline for obstructive IVH; N=500; PO: mRS 0-3 at day 180), and MISTIE-III trial (stereotactic thrombolysis [MIS+tPA] vs. conservative management; N=499; PO: mRS 0-3 at day 365). eGOS was derived from functional outcome scales obtained during the trials. Outcomes on eGOS were categorized into 5 subgroups: good outcomes: 7-8 (A), 5-6 (B), 4 (C), and poor outcomes: 3 (D), and 1-2 (E). Generalized, ordered logistic regression analysis was performed, adjusting for age, ICH location, stability ICH and IVH volumes, and randomization GCS.

Results: eGOS scales were available in 481 (96%) patients at day 180 in CLEAR-III and 478 (96%) patients at day 365 in MISTIE-III. In CLEAR-III, odds of being in eGOS category D (LSD) or E (death or VS) vs. the others, were approximately 40% lower for IVtPA group compared to saline group (aOR = 0.59; 95% CI, 0.38-0.90; p=0.016), and odds of being in category E (vs. the others) were almost 50% lower (aOR = 0.51; 95% CI, 0.33-0.80; p=0.004). VS occurred in 2.49% of IVtPA and 2.07% of saline group patients. In MISTIE-III, odds of being in eGOS category D or E (vs. the others) were not significantly different for MIS+tPA vs. conservative treatment: aOR = 0.84; 95% CI, 0.55-1.28; p=0.41), as were odds for being in eGOS category E (vs. the others), aOR = 0.77; 95% CI, 0.48-1.24; p=0.29).

Conclusions: The 5-category dichotomized eGOS (4-8 vs. 1-3) defines a functional outcome improvement in CLEAR-III at day 180, which was not observed using the PO with mRS. Use of eGOS did not result in a different interpretation of the MISTIE-III trial.

Abstract TMP27: Association Of The Serum Inflammatory Markers With The Periventricular And Deep White Matter Hyperintensity

Introduction: Markers of systemic and vascular inflammation have been associated with cerebral small vessel disease (cSVD). However, their association with cSVD lesions within individual white matter regions remains unclear. We hypothesized that there are different associations of serum cytokines with the periventricular white matter hyperintensity (PVWMH) and deep WMH (DWMH).

Methods: Apparently healthy participants aged ≥50 years with brain MRI in the Genetic Study of Atherosclerosis Risk were studied. Circulating inflammatory markers measured included: hs-CRP, IL-6, MCP1, ICAM, TNF-α, VCAM and IL-4. The relative association of these markers with PVWMH and DWMH within individuals were determined using multilevel linear models adjusted for age and cardiovascular risk factors.

Results: A total of 435 subjects (age 58.9±6.1 years, 58.4% female, 39.5% black) with moderate WMH burden were studied (Total WMH: 1703[607-4626] mm 3 , PVWMH :871[152-2593] mm 3 , DWMH: 388[157-1023] mm 3 ). Significant negative associations of total WMH volumes and hs-CRP (β=-0.2, P=0.04) as well as IL-6 (β=-0.15, p=0.04) were observed. The associations of total WMH with MCP-1, ICAM, VCAM, IL-4 and TNF-α were not significant. In the multilevel models, designed to compare difference between DWMH and PVWMH within individuals, there were significant differences in the relative association of PVWMH vs DWMH with hs-CRP and IL-6 (p=0.001 & p=0.04, respectively). DWMH was more strongly associated with hs-CRP and IL-6 (β=0.08, β=0.14, respectively) than PVWMH, which had negative association with these markers (β=-0.35, β=-0.05, respectively). There were no differences in the association of PVWMH vs DWMH and the other markers.

Conclusions: DWMH is positively associated with increasing IL-6 and CRP when compared to PVWMH which is negatively associated with them. This suggests that systemic inflammation is more preferentially associated with DWMH lesions.

Association of Vascular Properties With the Brain White Matter Hyperintensity in Middle-Aged Population

Background The periventricular white matter is more sensitive to the systemic hemodynamic alterations than the deep white matter because of differences in its vascular structure and systemic circulation relationship. We hypothesize that periventricular white matter hyperintensity (PVWMH) volume shows greater association than deep white matter hyperintensity (DWMH) volume with vascular properties (VPs) reflecting arterial stiffness and cardiovascular remodeling, indicators of the systemic circulation. Methods and Results A total of 426 participants (age, 59.0±6.1 years; 57.5% women; and 39.7% Black race) in the Genetic Study of Atherosclerosis Risk who were aged ≥50 years and had brain magnetic resonance imaging were studied. VPs included pulse pressure, hypertensive response to exercise, diastolic brachial artery diameter, diastolic common carotid artery diameter, common carotid artery distensibility coefficient, and left ventricular function. The relative associations of VPs with PVWMH and DWMH as multiple measures within the same individual were determined using multilevel linear models. We also determined if age modified the differences in VPs associations with PVWMH and DWMH. Our findings indicated that, within the same subject, PVWMH volume had greater association than DWMH volume with pulse pressure (P=0.002), hypertensive response to exercise (P=0.04), diastolic brachial artery diameter (P=0.012), and diastolic common carotid artery diameter (P=0.04), independent of age and cardiovascular risk factors. The differences of PVWMH versus DWMH associations with VPs did not differ at any age threshold. Conclusions We show, for the first time, that PVWMH has greater association than DWMH, independent of age, with vascular measurements of arterial stiffness and cardiovascular remodeling suggesting that changes in the systemic circulation affect the PVWMH and DWMH differently.

Abstract WMP20: Association Of Periventricular And Deep White Matter Hyperintensity With Cognitive Performance In A Middle-aged Population

Introduction: White matter hyperintensity (WMH) has been associated with manual dexterity performance in apparently healthy middle-aged population. However, the relative effect of WMH topographic distribution on cognition remains unknown. We hypothesized that periventricular WMH (PVWMH) is more strongly associated with manual dexterity and cognitive measures compared to deep WMH (DWMH) given its proximity to the white matter tracts involved in motor and executive functions.

Methods: Apparently healthy middle-aged participants in the Genetic Study of Atherosclerosis Risk with brain MRI and cognitive measurements were selected. Cognitive measures included delayed word recall short (DWRS) and long (DWRL), digit symbol substitution (DSS), word fluency (WF), digit span forward test (DSFT), backward (DSBT) and total (DSTS), and grooved peg board test (GPBT) including the dominant and non-dominant hand (GPBTD, GPBTnD). PVWMH and DWMH volumes were measured using semi-automated segmentation paradigm. The relative associations of these measurements with PVWMH and DWMH volumes as multiple measurements within the same individual further nested within families were determined using multilevel linear models adjusting for intracranial volume, age, sex and cardiovascular risk factors.

Results: 782 subjects were included (age 51.1±10.6, 58.4% female and 39% African American, PVWMH volume 437.4 [0-1646] mm 3 , DWMH volume 273.5 [76-665] mm 3 ). Within the same subject, PVWMH showed greater association than DWMH with worse performance on GPBT, GPBTD, GPBTnD, DWRS, and DWRL (P=0.006, 0.01, 0.01, 0.01 and 0.03, respectively) after adjusting for age and other cardiovascular risk factors. There was no difference in the association of PVWMH versus DWMH volumes with DSS, WF, DSFT, DSBT, DSTS (P=0.19, 0.52, 0.13, 0.6, and 0.6, respectively).

Conclusions: PVWMH shows greater association than DWMH with cognitive measures of manipulative manual dexterity and recall suggesting that PVWMH and DWMH may have different cognitive phenotypes in middle-aged population with cerebral small vessel disease.

Abstract WP14: Association Of Vascular Properties With The Periventricular And Deep White Matter Hyperintensity In Middle-age Population

Introduction: The periventricular white matter is more sensitive to alterations in the hemodynamics of the systemic circulation than the deep white matter due to differences in its vascular supply and relationship to systemic circulation. We hypothesize that periventricular white matter hyperintensity volume (PVWMH) shows greater association than deep white matter hyperintensity (DWMH) volume with vascular property measures of arterial stiffness (AS) and cardiovascular remodeling, important indicators of the systemic circulation.

Methods: Participants in the Genetic Study of Atherosclerosis Risk ≥ 50 years of age with brain MRI were selected. Vascular property measures included pulse pressure (PP), hypertension response to exercise (HRE), diastolic brachial artery (BA) diameter, diastolic common carotid artery (CCA) diameter, CCA distensibility coefficient, and left ventricular function. PVWMH and DWMH were measured using semi-automated segmentation approach. The relative associations of these parameters with PVWMH and DWMH volumes as multiple measures within the same individual further nested within families were determined using multilevel linear models. We also determined if differences between PVWMH and DWMH associations were modified by age.

Results: 426 participants (age 59.0±6.1 years, 57.5% females, and 39.7% African American) were included. Within the same subject, PVWMH volume showed greater association than DWMH volume with PP (P=0.002), HRE (p=0.04), diastolic BA diameter (p=0.012), and diastolic CCA diameter (p=0.04) independent of age and cardiovascular risk factors. This difference in PVWMH versus DWMH association with vascular properties did not differ at any age threshold.

Conclusions: We show for the first time that PVWMH volume has greater association than DWMH volume, independent of age, with vascular property measurements of AS and cardiovascular remodeling. Our findings suggest that changes in the systemic circulation may affect PVWMH and DWMH differently adding to a growing body of literature that PVWMH and DWMH may represent different phenotypes of cerebral small vessel disease.

Abstract TP137: Ethnic/racial Variations Of Intracerebral Hemorrhage Genetics (erich-gene) Study Protocol

Introduction: Epidemiologic studies of intracerebral hemorrhage (ICH) have consistently demonstrated variation in incidence, location, comorbidity burden, age-of-onset, and outcome by race and ethnicity, and genetic studies have identified differences in risk mediated by genetic risk factors such as Apolipoprotein E (APOE). We report the design and methods of the largest multi-ethnic genome-wide association study (GWAS) of ICH risk and outcome conducted to date.

Methods: The Ethnic/Racial Variations of ICH Genetics (ERICH-GENE) study is an international, multi-center, genetic case-control study of ICH. Cases are individuals with confirmed primary ICH with biosample availability and consent compatible with shareable genome-wide genotyping or previous genotyping. Central neuroimaging phenotype harmonization of case status, hemorrhage location, and imaging characteristics of cerebral small vessel disease including leukoaraiosis, atrophy, microbleeds, intraventricular hemorrhage severity and volume of ICH measurements will be performed. Controls are ICH-free individuals of compatible age and race/ethnicity from existing studies and biorepositories.

Results: As of August 2021, 2,002 ICH cases have been collected and genotyped, in addition to 2,558 already-genotyped ICH cases from the multi-ethnic ERICH study. 5,600 total new ICH cases will be genotyped under ERICH-GENE, with planned meta-analyses across existing ICH GWAS datasets and international biobanks totaling >20,000 cases. We are on schedule to meet our genotyping goal within the study period. Non-European ancestry cases are being prioritized for genotyping and ~66% of the previously genotyped ERICH cases are black or Hispanic. From available cases, a total of 10,621 neuroimaging studies have been uploaded for central adjudication to date with 6,278 having undergone harmonization.

Conclusions: ERICH-GENE is a large, multi-ethnic, international, centrally harmonized GWAS of ICH risk and outcome that will identify genetic risk factors across diverse populations for biological discovery and population-specific risk stratification.

Abstract MP26: Silent Small-vessel Cerebrovascular Disease In Individuals With A Family History Of Coronary Heart Disease: The Atherosclerosis Risk In Communities (ARIC) Study

Background: It is established that a family history of coronary heart disease (FHCHD) is associated with coronary atherosclerosis in healthy first-degree relatives, but the extent to which FHCHD is associated with silent cerebrovascular disease (cSVD) is unknown. We hypothesized a higher prevalence of cSVD in healthy persons with FHCHD, independent of traditional risk factors, compared to those without FHCHD.

Methods: ARIC is a community-based cohort study with self-reported family history data and brain magnetic resonance imaging (visit 5; 2011-13). The association between binary markers of cSVD (lacunar infarcts and/or cerebral microbleeds), or log-transformed white matter hyperintensity volume (WMH), and FHCHD (parent and/or sibling), or number of relatives was examined using separate adjusted multivariable logistic or linear regression models respectively. Sensitivity analysis (N=183) excluded prevalent CHD. Race interaction terms were included.

Results: Of 1828 participants (76±5yo, 60% female, 28% black), 787 had FHCHD (699 parental, 209 sibling FHCHD). There were increased adjusted odds of lacunar infarct among those with parental FHCHD (Table). An increased odds of cerebral microbleeds were seen among those with sibling history but not parental. Effect estimates were similar when excluding those with prevalent CHD (Table). Greater number of siblings affected was associated with higher odds of lacunar infarct (OR 1.35, CI 1.04-1.74), lobar (OR 1.53, CI 1.12-2.09) and subcortical microbleeds (OR 1.30, CI 1.01-1.66). Odds of a lacunar infarct being present were higher among blacks (p-interaction 0.04) with paternal FHCHD (OR 2.20, CI 1.35-3.58) compared to whites (OR 1.17, CI 0.87-1.56). Neither FHCHD nor number of affected relatives was associated with WMH.

Conclusions: Our results suggest that some cSVD manifestations are associated with FHCHD, potentially representing shared mechanisms in different vascular beds, and perhaps a genetic propensity for vascular disease.

Abstract P65: Arterial Stiffness Relationship With Periventricular and Deep White Matter Hyperintensities in a Middle-Aged Population

Introduction and hypothesis: Periventricular white matter (PVWM) is perfused by perforators originating from the proximal large caliber cerebral arteries with direct transmission of systemic hemodynamic changes as compared to the deep white matter (DWM) that is perfused by distal perforators with dampened transmission. We hypothesized that PVWM hyperintensities (PVWMH) are more strongly associated with the systemic vascular properties representing arterial stiffness (AS) due to vascular aging and hypertension compared to DWM hyperintensities (DWMH).

Methods: Apparently healthy first degree relatives of subjects with coronary artery disease who had brain MRI as participants in GeneSTAR were selected. PVWMH and DWMH volumes were computed by an automated analysis software. Arterial stiffness indicators included peak systolic blood pressure during treadmill test, pulse pressure (PP), brachial artery (BA) diameter, carotid distensibility index, and diastolic dysfunction estimated by filling and systolic emptying rates (SER) on sestamibi cardiac scan. Statistical analysis was completed using unadjusted and age-adjusted linear regression models in the cohort that was divided into 4 quartiles based on age distribution (1 st : 29-43, 2 nd : 44-51, 3 rd : 52-59, 4 th : 60-74).

Results: 782 participants were included (age 51.05±10.6 years, 58.4% female, 39% African American, PVWMH volume 1977.01±5195.81 ml and DWMH volume 625.93±1108.37 ml). In the unadjusted analysis, PVWMH showed association with PP in the 1 st and 3 rd age quartiles (p= 0.02 and 0.03, respectively) and SER in the 2 nd and 4 th age quartiles (p=0.04 and 0.03). This relationship remained significant in the adjusted analysis for SER (p=0.047, and 0.032, respectively) and in the 1 st age quartile for PP (P=0.02). DWMH relationship with BA diameter was significant in the 2 nd age quartile in the unadjusted and adjusted models (P=0.011, and 0.02, respectively). DWMH was also associated with ratio of cardiac filling/SER (P=0.039 and 0.047) in the 1 st age quartile.

Conclusions: In this exploratory analysis, AS measures show different relationships to PVWMH and DWMH across age groups in middle-aged population suggesting a potential mechanistic role of AS in WMH pathology.

Comparison of Traumatic Intracranial Hemorrhage Expansion and Outcomes Among Patients on Direct Oral Anticoagulants Versus Vitamin k Antagonists

BACKGROUND

With increasing use of direct oral anticoagulants (DOACs) and availability of new reversal agents, the risk of traumatic intracranial hemorrhage (tICH) requires better understanding. We compared hemorrhage expansion rates, mortality, and morbidity following tICH in patients treated with vitamin k antagonists (VKA: warfarin) and DOACs (apixaban, rivaroxaban, dabigatran).

METHODS

Retrospective chart review of patients from 2010 to 2017 was performed to identify patients with imaging diagnosis of acute traumatic intraparenchymal, subdural, subarachnoid, and epidural hemorrhage with preadmission use of DOACs or VKAs. We identified 39 patients on DOACs and 97 patients on VKAs. Demographic information, comorbidities, hemorrhage size, and expansion over time, as well as discharge disposition and Glasgow Outcome Scale (GOS) were collected. Primary outcome was development of new or enlargement of tICH within the first 48 h of initial CT imaging.

RESULTS

Of 136 patients with mean (SD) age 78.7 (13.2) years, most common tICH subtype was subdural hematoma (N = 102/136; 75%), and most common mechanism was a fall (N = 130/136; 95.6%). Majority of patients in the DOAC group did not receive reversal agents (66.7%). Hemorrhage expansion or new hemorrhage occurred in 11.1% in DOAC group vs. 14.6% in VKA group (p = 0.77) at a median of 8 and 11 h from initial ED admission, respectively (p = 0.82). Patients in the DOAC group compared to VKA group had higher median discharge GOS (4 vs. 3 respectively, p = 0.03), higher percentage of patients with good outcome (GOS 4-5, 66.7% vs. 40.2% respectively, p = 0.005), and higher rate of discharge to home or rehabilitation (p = 0.04).

CONCLUSIONS

We report anticoagulation-associated tICH outcomes predominantly due to fall-related subdural hematomas. Patients on DOACs had lower tICH expansion rates although not statistically significantly different from VKA-treated patients. DOAC-treated patients had favorable outcomes versus VKA group following tICH despite low use of reversal strategies. DOAC use may be a safer alternative to VKA in patients at risk of traumatic brain hemorrhage.

Cerebral small vessel disease genomics and its implications across the lifespan

White matter hyperintensities (WMH) are the most common brain-imaging feature of cerebral small vessel disease (SVD), hypertension being the main known risk factor. Here, we identify 27 genome-wide loci for WMH-volume in a cohort of 50,970 older individuals, accounting for modification/confounding by hypertension. Aggregated WMH risk variants were associated with altered white matter integrity (p = 2.5×10-7) in brain images from 1,738 young healthy adults, providing insight into the lifetime impact of SVD genetic risk. Mendelian randomization suggested causal association of increasing WMH-volume with stroke, Alzheimer-type dementia, and of increasing blood pressure (BP) with larger WMH-volume, notably also in persons without clinical hypertension. Transcriptome-wide colocalization analyses showed association of WMH-volume with expression of 39 genes, of which four encode known drug targets. Finally, we provide insight into BP-independent biological pathways underlying SVD and suggest potential for genetic stratification of high-risk individuals and for genetically-informed prioritization of drug targets for prevention trials.

White Matter Injury Is Associated with Reduced Manual Dexterity and Elevated Serum Ceramides in Subjects with Cerebral Small Vessel Disease

INTRODUCTION

We have demonstrated that asymptomatic cerebral small vessel disease (cSVD) measured by white matter hyperintensity volume is associated with reduced manipulative manual dexterity on the Grooved Peg Board Test (GPBT) in middle-aged healthy individuals with a family history of early coronary artery disease. In this current study, we aim to identify the association of subcortical white matter microstructural impairment measured by diffusion tensor imaging, manual dexterity measured by GPBT and circulating serums ceramide, another marker for white matter injury. We hypothesize that lower regional fractional anisotropy (rFA) is associated with worse performance on GPBT and elevated serum ceramides in the same study population.

METHODS

rFA of 48 regions representing the subcortical white matters were analyzed in GeneSTAR participants in addition to serum ceramides and GPBT scores. Unadjusted univariable analyses with Bonferroni correction for multiple comparisons were completed using Spearman correlation for testing the associations between ceramides, rFA of subcortical white matter, and GPBT performance. Subsequently, sensitivity analyses were performed after excluding the participants that had any physical limitation that may influence their performance on GPBT. Finally, in the adjusted analysis using generalized estimating equation, linear regression models were performed for the areas that met significance threshold in the unadjusted analyses.

RESULTS

112 subjects (age [49 ± 11], 51% female, 39.3% African American) were included. Adjusted analyses for the significant correlations that met the Bonferroni correction threshold in the unadjusted univariable analyses identified significant negative associations between rFA of the right fornix (RF) and log-GPBT score (β = -0.497, p = 0.037). In addition, rFA of RF negatively correlated with log serum ceramide levels (C18: β = -0.03, p = 0.003, C20: β = -0.0002, p = 0.004) and rFA of left genu of corpus callosum negatively correlated with log C18 level (β = -0.0103, p = 0.027).

CONCLUSIONS

These results demonstrate that subcortical microstructural white matter disruption is associated with elevated serum ceramides and reduced manual dexterity in a population with cSVD. These findings suggest that injury to white matter tracts undermines neural networks, with functional consequences in a middle-aged population with cardiovascular risk factors.

Common Genetic Variation Indicates Separate Causes for Periventricular and Deep White Matter Hyperintensities

BACKGROUND AND PURPOSE

Periventricular white matter hyperintensities (WMH; PVWMH) and deep WMH (DWMH) are regional classifications of WMH and reflect proposed differences in cause. In the first study, to date, we undertook genome-wide association analyses of DWMH and PVWMH to show that these phenotypes have different genetic underpinnings.

METHODS

Participants were aged 45 years and older, free of stroke and dementia. We conducted genome-wide association analyses of PVWMH and DWMH in 26,654 participants from CHARGE (Cohorts for Heart and Aging Research in Genomic Epidemiology), ENIGMA (Enhancing Neuro-Imaging Genetics Through Meta-Analysis), and the UKB (UK Biobank). Regional correlations were investigated using the genome-wide association analyses -pairwise method. Cross-trait genetic correlations between PVWMH, DWMH, stroke, and dementia were estimated using LDSC.

RESULTS

In the discovery and replication analysis, for PVWMH only, we found associations on chromosomes 2 (NBEAL), 10q23.1 (TSPAN14/FAM231A), and 10q24.33 (SH3PXD2A). In the much larger combined meta-analysis of all cohorts, we identified ten significant regions for PVWMH: chromosomes 2 (3 regions), 6, 7, 10 (2 regions), 13, 16, and 17q23.1. New loci of interest include 7q36.1 (NOS3) and 16q24.2. In both the discovery/replication and combined analysis, we found genome-wide significant associations for the 17q25.1 locus for both DWMH and PVWMH. Using gene-based association analysis, 19 genes across all regions were identified for PVWMH only, including the new genes: CALCRL (2q32.1), KLHL24 (3q27.1), VCAN (5q27.1), and POLR2F (22q13.1). Thirteen genes in the 17q25.1 locus were significant for both phenotypes. More extensive genetic correlations were observed for PVWMH with small vessel ischemic stroke. There were no associations with dementia for either phenotype.

CONCLUSIONS

Our study confirms these phenotypes have distinct and also shared genetic architectures. Genetic analyses indicated PVWMH was more associated with ischemic stroke whilst DWMH loci were implicated in vascular, astrocyte, and neuronal function. Our study confirms these phenotypes are distinct neuroimaging classifications and identifies new candidate genes associated with PVWMH only.

Abstract WMP97: Haptoglobin is Associated With Increased Early Perihematoma Edema Progression in Spontaneous Intracranial Hemorrhage

Introduction: Perihematomal edema in intracranial hemorrhage (ICH) is influenced by free hemoglobin clearance and inflammation. Serum Haptoglobin (Hp) binds free hemoglobin, affecting clearance as well as free radical production, resulting in inflammation. Of the three phenotypes of Haptoglobin, Hp 1-1 has the greatest effect on free hemoglobin clearance. We hypothesized that individuals with the Hp 1-1 phenotype have different rates of early perihematomal edema formation as compared to those with Hp 2-1 and Hp 2-2.

Methods: We determined Hp phenotype, ICH volume, and rate of early change in perihematomal volume (ePHE) in participants from three prospectively collected ICH cohorts; Johns Hopkins University hospital (JHH), Massachusetts General Hospital (MGH), and the MISTIE III trial. The association of Hp phenotypes 1-1, 2-1, 2-2, with ePHE, while controlling for key clinical characteristics was analyzed using a multivariate model. Findings: 166 participants, 57 from JHH, 30 from MGH, and 79 from the MISTIE III trial were included: 73 (44%) female, 41(25%) African Americans, 34 (20%) diabetics, 133 (80%) with hypertension, and 75 (45%) active smokers. There were 15 subjects with Hp phenotype 1-1, 86 with 2-1 and 65 with 2-2. In the adjusted analysis, controlling for race, diabetes, hypertension, smoking status, and change in intracranial hemorrhage volume over time (cc/hr), Hp 1-1 had a significantly increased estimated mean rate of ePHE at 1·15, (95% CI 0·58-1·71) as compared to all other Hp 2-1 or Hp 2-2 containing phenotypes (0·30, 95% CI 0·06-0·54; 0.29 95% CI 0·02-0·56). Neither mortality nor discharge mRS differed between Hp phenotypes.

Interpretation: Haptoglobin phenotype is associated with ePHE. Hp 1-1 significantly increased mean rate of ePHE suggests that haptoglobin phenotype may be a key player in understanding the multiphasic progression of PHE in sICH, which may help identify windows for targeted interventions to improve clinical outcomes.

Conclusion: In our adjusted models, patients with the Haptoglobin 1-1 phenotype had an increased rate of ePHE formation within the first 96 hours. The Hp 1-1 phenotype may increase perihematomal progression in sICH. A larger prospective observational study is warranted.

Abstract 37: Increased Mean Transit Time and Blood Brain Permeability in Asymptomatic White Matter Lesions of Ischemic Origin

Introduction: White matter lesions of presumed ischemic origin (WMH) have been associated with increased risk of stroke, cognitive and motor decline, and are a subject of public health research. Engineering new MRI pipelines allowing for determination of mean transit time (MTT), and blood brain barrier permeability (BBBP), within WMH lesions is required for long-term population-based studies of lesion progression in patients with dementia and vascular cognitive impairment.

Methods: WMH lesion volumes in 24 asymptomatic individuals was determined using an automated segmentation methodology, S3DL, with manual correction to remove false positives. A double contrast injection scheme was used to measure both K trans using dynamic contrast enhanced (DCE) imaging and K 2 using dynamic susceptibility contrast (DSC) imaging which also provided perfusion-related measures. BBBP was measured as k 2 within segmented WMH lesions and compared with normal white and gray matter.

Results: The mean transit time (MTT) was found to be significantly prolonged (8.11, p<0.001Wilcoxon Signed-Rank Test) in WMH lesions when compared to normal appearing white and gray matter. There was no significant difference in DCE-K trans (0.018, p=0.351) between the lesions and the white/gray matter. Permeability measured in the WMH lesions using the DSC-K 2 method was increased and was correlated withincreasing total WMH lesion volume (spearman correlation 0.44; p< 0.046).

Conclusion: In this first study using an advanced WMH lesion automated segmentation pipeline, we measured DCE and DSC perfusion and permeability variables within WMH lesions and compared them to normal white and grey matter in healthy people. We observed increasing MTT, within WMH lesions as compared to unaffected white and gray matter. Using the DSC-K 2 method, BBBP was higher within WMH lesions in these asymptomatic people, and correlated with increasing total lesion volume.

Perihematomal Edema After Intracerebral Hemorrhage in Patients With Active Malignancy

Background and Purpose- Patients with active malignancy are at risk for intracerebral hemorrhage (ICH). We aimed to characterize perihematomal edema (PHE) and hematoma volumes after spontaneous nontraumatic ICH in patients with cancer without central nervous system involvement. Methods- Patients with active malignancy who developed ICH were retrospectively identified through automated searches of institutional databases. Control patients were identified with ICH and without active cancer. Demographic and cancer-specific data were obtained by chart review. Hematoma and PHE volumes were determined using semiautomated methodology. Univariate and multivariate linear regression models were created to assess which variables were associated with hematoma and PHE expansion. Results- Patients with cancer (N=80) and controls (N=136) had similar demographics (all P>0.20), although hypertension was more prevalent among controls (P=0.004). Most patients with cancer had received recent chemotherapy (n=45, 56%) and had recurrence of malignancy (n=43, 54%). Patients with cancer were thrombocytopenic (median platelet count 90 000 [interquartile range, 17 500-211 500]), and most had undergone blood product transfusion (n=41, 51%), predominantly platelets (n=38, 48%). Thirty-day mortality was 36% (n=29). Patients with cancer had significantly increased PHE volumes (23.67 versus 8.61 mL; P=1.88×10^-9) and PHE-to-ICH volume ratios (2.26 versus 0.99; P=2.20×10^-16). In multivariate analyses, variables associated with PHE growth among patients with cancer were ICH volume (β=1.29 [95% CI, 1.58-1.30] P=1.30×10^-5) and platelet transfusion (β=15.67 [95% CI, 3.61-27.74] P=0.014). Variables associated with 30-day mortality were ICH volume (odds ratio, 1.06 [95% CI, 1.03-1.10] P=6.76×10^-5), PHE volume (odds ratio, 1.07 [95% CI, 1.04-1.09] P=7.40×10^-6), PHE growth (odds ratio, 1.05 [95% CI, 1.01-1.10] P=0.01), and platelet transfusion (odds ratio, 1.48 [95% CI, 1.22-1.79] P=0.0001). Conclusions- Patients with active cancer who develop ICH have increased PHE volumes. PHE growth was independent of thrombocytopenia but associated with blood product transfusion. Thirty-day mortality was associated with PHE and ICH volumes and blood product transfusion.

Standards for Neurologic Critical Care Units: A Statement for Healthcare Professionals from The Neurocritical Care Society

Neurocritical care is a distinct subspecialty focusing on the optimal management of acutely ill patients with life-threatening neurologic and neurosurgical disease or with life-threatening neurologic manifestations of systemic disease. Care by expert healthcare providers to optimize neurologic recovery is necessary. Given the lack of an organizational framework and criteria for the development and maintenance of neurological critical care units (NCCUs), this document is put forth by the Neurocritical Care Society (NCS). Recommended organizational structure, personnel and processes necessary to develop a successful neurocritical care program are outlined. Methods: Under the direction of NCS Executive Leadership, a multidisciplinary writing group of NCS members was formed. After an iterative process, a framework was proposed and approved by members of the writing group. A draft was then written, which was reviewed by the NCS Quality Committee and NCS Guidelines Committee, members at large, and posted for public comment. Feedback was formally collated, reviewed and incorporated into the final document which was subsequently approved by the NCS Board of Directors.

Exome Chip Analysis Identifies Low-Frequency and Rare Variants in MRPL38 for White Matter Hyperintensities on Brain Magnetic Resonance Imaging

Background and Purpose- White matter hyperintensities (WMH) on brain magnetic resonance imaging are typical signs of cerebral small vessel disease and may indicate various preclinical, age-related neurological disorders, such as stroke. Though WMH are highly heritable, known common variants explain a small proportion of the WMH variance. The contribution of low-frequency/rare coding variants to WMH burden has not been explored. Methods- In the discovery sample we recruited 20 719 stroke/dementia-free adults from 13 population-based cohort studies within the Cohorts for Heart and Aging Research in Genomic Epidemiology consortium, among which 17 790 were of European ancestry and 2929 of African ancestry. We genotyped these participants at ≈250 000 mostly exonic variants with Illumina HumanExome BeadChip arrays. We performed ethnicity-specific linear regression on rank-normalized WMH in each study separately, which were then combined in meta-analyses to test for association with single variants and genes aggregating the effects of putatively functional low-frequency/rare variants. We then sought replication of the top findings in 1192 adults (European ancestry) with whole exome/genome sequencing data from 2 independent studies. Results- At 17q25, we confirmed the association of multiple common variants in TRIM65, FBF1, and ACOX1 ( P<6×10^-7). We also identified a novel association with 2 low-frequency nonsynonymous variants in MRPL38 (lead, rs34136221; P_EA=4.5×10^-8) partially independent of known common signal ( P_{EA(conditional)}=1.4×10^-3). We further identified a locus at 2q33 containing common variants in NBEAL1, CARF, and WDR12 (lead, rs2351524; P_all=1.9×10^-10). Although our novel findings were not replicated because of limited power and possible differences in study design, meta-analysis of the discovery and replication samples yielded stronger association for the 2 low-frequency MRPL38 variants ( P_rs34136221=2.8×10^-8). Conclusions- Both common and low-frequency/rare functional variants influence WMH. Larger replication and experimental follow-up are essential to confirm our findings and uncover the biological causal mechanisms of age-related WMH.

A genome-wide association study identifies genetic loci associated with specific lobar brain volumes

Brain lobar volumes are heritable but genetic studies are limited. We performed genome-wide association studies of frontal, occipital, parietal and temporal lobe volumes in 16,016 individuals, and replicated our findings in 8,789 individuals. We identified six genetic loci associated with specific lobar volumes independent of intracranial volume. Two loci, associated with occipital (6q22.32) and temporal lobe volume (12q14.3), were previously reported to associate with intracranial and hippocampal volume, respectively. We identified four loci previously unknown to affect brain volumes: 3q24 for parietal lobe volume, and 1q22, 4p16.3 and 14q23.1 for occipital lobe volume. The associated variants were located in regions enriched for histone modifications (DAAM1 and THBS3), or close to genes causing Mendelian brain-related diseases (ZIC4 and FGFRL1). No genetic overlap between lobar volumes and neurological or psychiatric diseases was observed. Our findings reveal part of the complex genetics underlying brain development and suggest a role for regulatory regions in determining brain volumes.

Correction to: Standards for Neurologic Critical Care Units: A Statement for Healthcare Professionals from The Neurocritical Care Society

The authors note that there is a discrepancy between the text of the paper and Table 2 regarding physician subspecialty certification requirements in neurocritical care for Level II centers.

Haptoglobin genotype and aneurysmal subarachnoid hemorrhage: Individual patient data analysis

OBJECTIVE

To perform an individual patient-level data (IPLD) analysis and to determine the relationship between haptoglobin (HP) genotype and outcomes after aneurysmal subarachnoid hemorrhage (aSAH).

METHODS

The primary outcome was favorable outcome on the modified Rankin Scale or Glasgow Outcome Scale up to 12 months after ictus. The secondary outcomes were occurrence of delayed ischemic neurologic deficit, radiologic infarction, angiographic vasospasm, and transcranial Doppler evidence of vasospasm. World Federation of Neurological Surgeons (WFNS) scale, Fisher grade, age, and aneurysmal treatment modality were covariates for both primary and secondary outcomes. As preplanned, a 2-stage IPLD analysis was conducted, followed by these sensitivity analyses: (1) unadjusted; (2) exclusion of unpublished studies; (3) all permutations of HP genotypes; (4) sliding dichotomy; (5) ordinal regression; (6) 1-stage analysis; (7) exclusion of studies not in Hardy-Weinberg equilibrium (HWE); (8) inclusion of studies without the essential covariates; (9) inclusion of additional covariates; and (10) including only covariates significant in univariate analysis.

RESULTS

Eleven studies (5 published, 6 unpublished) totaling 939 patients were included. Overall, the study population was in HWE. Follow-up times were 1, 3, and 6 months for 355, 516, and 438 patients. HP genotype was not associated with any primary or secondary outcome. No trends were observed. When taken through the same analysis, higher age and WFNS scale were associated with an unfavorable outcome as expected.

CONCLUSION

This comprehensive IPLD analysis, carefully controlling for covariates, refutes previous studies showing that HP1-1 associates with better outcome after aSAH.

Intensive Care Unit Readmission in Patients With Primary Brain Injury and Tracheostomy

BACKGROUND

Readmission for ventilator support in tracheostomy patients with primary brain injury is often attributed to failure of airway protection and aspiration pneumonia. Data regarding the incidence of intensive care unit readmissions and associated factors in these patients are limited.

OBJECTIVES

To determine the factors associated with intensive care unit readmission among tracheostomy patients with primary brain injury, as compared with tracheostomy patients without primary brain injury.

METHODS

Prospectively acquired data from an ongoing tracheostomy registry at an academic health center were reviewed retrospectively. A total of 164 patients more than 18 years of age who received an elective tracheostomy and had at least 1 readmission to the intensive care unit between 2007 and 2013 were included.

RESULTS

The incidence of mechanical ventilation resumption and readmission was significantly higher in patients with than without primary brain injury (P = .005). Patients requiring tracheostomy for airway protection were at a higher risk for atelectasis (odds ratio, 8.23; P = .05). In patients with primary brain injury, a higher Glasgow Coma Scale score was associated with a lower risk for atelectasis (odds ratio, 0.84; P = .04). Mean (SD) Glasgow Coma Scale score was higher in patients without primary brain injury (10.64 [3.98]) than in patients with primary brain injury (8.62 [4.57]; P = .006).

CONCLUSIONS

Tracheostomy patients with primary brain injury may have central nervous system-mediated respiratory compromise associated with reduced Glasgow Coma Scale score, increased atelectasis, and shorter duration of ventilator dependency.

Abstract WP413: White Matter Tract Disruption on Diffusor Tensor Imaging is Associated With Serum Ceramides in a Healthy Middle-Aged High Risk Population

Introduction: White matter tract disruption (WMTD) on Diffusion Tensor Imaging (DTI) may reflect early axonal disruption and tract injury and identify risk for dementia. Brain ceramides play a role in processes also associated with dementia risk. We hypothesized that circulating ceramide levels might serve as biomarkers of WMTD in a population at high risk for early vascular disease. We studied six ceramides and WMTD using fractional anisotropy (FA) on DTI in healthy relatives of patients with early coronary disease. We have previously shown a high prevalence of white matter hyperintensities (WMH) and significant associations between WMH volumes, FA, and lower cognitive function in healthy relatives.

Methods: DTI was acquired with Phillips 3T MRI. FA was measured for 181 regions of the segmented brain using Eve atlas. 48 relevant regions with susceptibility for WMTD were analyzed. Serum ceramides were measured using high performance liquid chromatography. Spearman correlations and GEE linear regression analyses (adjusted for age, sex, race, education and family relatedness) were used. We set the significance level to meet the Bonferroni threshold of 0.00017 (0.05 / 48 regions/6 ceramides).

Results: Subjects, N=112, had a mean age of 49± 11 years; education 14 ± 3 years; 49% male; 39% African American, 61% European American). Serum levels for ceramides designated C18:0, C20:0, and C22:0 were significantly negatively correlated with FA in the right fornix (C18:0, R=-0.40, p=1.3 x10 -5 , C20:0, R=-0.41, p= 6.1 x 10 -6 , C22:0, R=-0.33, p=4.3 x10 -4 ). C18:0 was negatively correlated with the left genu of corpus callosum (R=-0.39, p=2.6 x10 -5 ) and right body of corpus callosum (R=-0.31, p=8.5 x10 -4 ). An additional ceramide, C24:0, was correlated with both sides of the posterior limb of internal capsule (left R=0.34, p=2.5 x10 -4 ; right R=0.34, p=2.8 x10 -4 ). All ceramide-FA associations were significant (p<0.05) after fully adjusted GEE regression.

Conclusions: We show a robust relationship between serum ceramides and WMTD using FA in a middle-aged, cognitively intact at-risk population enriched for early WMH. Thus, serum ceramide levels may reflect subtle alterations in white matter tract microstructure at an early preclinical stage. <!--EndFragment-->

Abstract TMP91: White Matter Lesion Progression and Cognitive Function Over 5-Years in a Young Susceptible Population

Introduction: Cerebrovascular disease (CVD) and vascular risk factors cluster in families of patients with early-onset coronary artery disease (CAD). In a prior cross-sectional study of 714 healthy middle-aged relatives, we found a high prevalence of early white matter hyperintensity lesions (WMHL) and associated lower cognitive function. Prior WMHL studies have included elderly or demented subjects. Rate of WMHL progression and cognitive decline in quiescent preclinical healthy middle-aged persons remains unknown.

Methods: We studied WMHL and cognitive function over 5 years in 20 healthy relatives, age 50-59, of patients with CAD <60 years of age (one subject per family). Persons with any physical or neurological abnormality were excluded. At baseline and follow-up, subjects underwent 3-Tesla brain magnetic resonance imaging. WMHL volumes were determined using automated segmented volumes measured from FLAIR and MPRAGE using a previously described automated pipeline. Cognitive function was measured with the: Delayed Recall, Digit Symbol Substitution, Verbal Fluency, Digit Span, and Grooved Pegboard tests.

Results: Our 20 participants were: 50% male, 45% African American (AA), average age was 54.1 (SD 1.57) years, 45% with HTN, 15% smokers, and 50% obese. WMHL prevalence was 92%. The average change in WMHL volume was 819 mm 3 (P<0.0008); this was significant for men (p=0.006), women (p= 0.062), AAs (p= 0.019), and European Americans (EA) (p= 0.018). Decline occurred in all cognitive function tests (average P across all tests was <0.001) in all races and sexes. Vascular risk factors did not change from baseline to follow-up.

Conclusion: These striking findings are among the first to demonstrate significant quantitative WMHL volume progression and cognitive decline in a healthy middle-aged population over just 5 years, in AA and EA and both sexes. This small pilot study suggests that early quiescent brain white matter lesion progression and early multidimensional cognitive decline can be detected in healthy susceptible populations using state-of-the-art quantitative volumetric imaging techniques.

Abstract TMP93: Hypertension is Associated with Disruption of White Matter Tracts in Healthy Middle-aged Persons at Risk for Vascular Disease

Background: Fractional anisotropy (FA) measured by Diffusion Tensor Imaging (DTI) is a sensitive biomarker of white matter (WM) integrity and offers a means to detect early axonal disruption and attendant cognitive impairment secondary to vascular disease.

Hypothesis: We hypothesized that hypertension (HTN), of all known risk factors, is most closely linked to early WM tract injury in apparently healthy high risk relatives of patients with early-onset coronary artery disease (CAD).

Methods: DTI was acquired on a Phillips 3T MRI scanner (slice thickness 2.2 mm, field of view 212X212 mm and b-value 700 mm 2 /s) for relatives of CAD patients. The brain was segmented into 181 regions using the Eve Atlas, Large Deformation Diffeomorphic Metric Mapping paradigm, and 48 regions representing the deep WM were selected for analysis. Mean regional FA (rFA) was assessed using t-tests in persons with and without smoking, HTN, diabetes. Continuous variable association with rFA was tested using Spearman correlations. Covariate-adjusted GEE linear regression (corrected for nonindependence of families) was performed for regions meeting the Bonferroni threshold of 0.001 (0.05/48).

Results: 116 subjects had DTI data (mean age 49.5±11, 57% males, 40.5% African Americans, 23% smokers, 36% hypertensives, 12% diabetics). rFA was not significantly associated with diabetes or current smoking. Moreover, rFA was not significantly correlated with glucose level, LDL, total cholesterol or body mass index. However, patients with HTN showed a significantly lower rFA compared to normotensives in the left (L) genu of corpus callosum, L external capsule, right (R) cingulum, L fornix/ stria terminalis, L and R column and body of fornix, and R sagittal stratum. After adjusting for age, sex and race, this relation remained significant in the R sagittal stratum (P=0.012) and R cingulum (P=0.001). Systolic blood pressure (SBP) correlated with rFA after adjustment in the L superior longitudinal fasciculus as well (unadjusted rho=-0.309, p=0.00073, adjusted beta =-1.08+-0.47, P=0.02).

Conclusions: Of all of the risk factors, as hypothesized, HTN and SBP were significantly associated with early WM tract injury in areas related to cognition in middle-aged persons at risk for vascular disease.

Novel genetic loci underlying human intracranial volume identified through genome-wide association

Intracranial volume reflects the maximally attained brain size during development, and remains stable with loss of tissue in late life. It is highly heritable, but the underlying genes remain largely undetermined. In a genome-wide association study of 32,438 adults, we discovered five previously unknown loci for intracranial volume and confirmed two known signals. Four of the loci were also associated with adult human stature, but these remained associated with intracranial volume after adjusting for height. We found a high genetic correlation with child head circumference (ρgenetic = 0.748), which indicates a similar genetic background and allowed us to identify four additional loci through meta-analysis (Ncombined = 37,345). Variants for intracranial volume were also related to childhood and adult cognitive function, and Parkinson's disease, and were enriched near genes involved in growth pathways, including PI3K-AKT signaling. These findings identify the biological underpinnings of intracranial volume and their link to physiological and pathological traits.

Haptoglobin 2-2 Genotype Is Associated With Cerebral Salt Wasting Syndrome in Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Haptoglobin (Hp) genotype has been shown to be a predictor of clinical outcomes in subarachnoid hemorrhage. Cerebral salt wasting (CSW) has been suggested to precede the development of symptomatic vasospasm.

OBJECTIVE

To determine if Hp genotype was associated with CSW and subsequent vasospasm after aneurysmal subarachnoid hemorrhage.

METHODS

Hp genotypic determination was done for patients admitted with a diagnosis of subarachnoid hemorrhage. Outcome measures included CSW, delayed cerebral infarction, and Glasgow Outcome Score of 4 to 5 at 30 days. Criteria for CSW included hyponatremia <135 mEq/L, and urine output >4 L in 12 hours with urine sodium >40 mEq/L.

RESULTS

A total of 133 patients were included in the study. The 3 Hp subgroups did not differ in terms of baseline characteristics. CSW occurred in 1 patient (3.4%) with Hp 1-1, 8 (14.0%) patients with Hp 2-1, and 15 (31.9%) patients with Hp 2-2 (P = .004). In the multivariate regression model, Hp 2-2 was associated with CSW (odds ratio [OR]: 4.94; CI: 1.78-17.43; P = .01), but Hp 2-1 was not (OR: 2.92; CI: 0.56-4.95; P = .15) compared with Hp 1-1. There were no associations between Hp genotypes and functional outcome or delayed cerebral infarction. CSW was associated with delayed cerebral infarction (OR: 7.46; 95% CI: 2.54-21.9; P < .001).

CONCLUSION

Hp 2-2 genotype was an independent predictor of CSW after subarachnoid hemorrhage. Because CSW is strongly associated with delayed cerebral infarction, the use of Hp genotype testing requires more investigation, and larger prospective confirmation is warranted. Additionally, a more objective definition of CSW needs to be delineated.

Abstract WP434: Decreased Manual Dexterity is Associated With Low Fractional Anisotropy in the Fornix of Healthy Middle-aged Persons at Risk for Vascular Disease

Introduction: Decreased fornix fractional anisotropy (FA) on diffusion tensor imaging (DTI) in normal ageing has been associated with impaired problem solving, working memory and motor tasking, but its role in multi-dimensional cognitive-motor tasks in apparently healthy people has not been studied. Also, the extent of its association with vascular disruption remains unclear. White matter lesions of presumed ischemic origin on MRI are associated with decrements in Grooved Pegboard test (GPBT) in young asymptomatic family members of probands with premature coronary artery disease (CAD).

Hypothesis: We hypothesized that decrements in GPBT in this population, is associated with decreased FA in relevant brain regions.

Methods: The GPBT was averaged for both hands. DTI was acquired on a Phillips 3T scanner (slice thickness 2.2 mm, field of view 212X212 mm and b-value 700 mm 2 /s). The brain was segmented into 181 regions with Large Deformation Diffeomorphic Metric Mapping using the Eve atlas. Pearson correlations of regional FA values and log-transformed GPBT scores were performed and Multivariable GEE linear regression (adjusted for family relatedness) was done for regions meeting the Bonferroni threshold of 0.00028 (0.05/181).

Results: Subjects with DTI and GPBT data were included (N=115, mean age 49± 11 years; mean education 14 ± 3 years; 49% male; 41% African American). GPBT score was normal (106±15) seconds. Higher GPBT (worse performance) was negatively correlated with FA in regions of the left (L) and right (R) frontal and temporal lobes and L&R corpus callosum not meeting Bonferroni threshold (p=0.0046, 0.036, 0.026, 0.0015, 0.02, 0.0007), whereas the L&R fornix and L external capsule (EC) did meet threshold (L fornix R=-0.37, p=5.9E-05; R fornix R=-0.47, p=1.3E-07, L EC R=-0.35, p=8.1E-05). After adjusting for age, sex, race, and education every 25% lower FA in the R fornix was associated with 12% decrement in GBPT (R fornix p=0.05, L fornix and EC p=0.19).

Conclusions: Decreased fornix FA is associated with worse manual dexterity in a healthy middle-aged population with a family history of early onset CAD, at risk for future cerebrovascular disease. This suggests injury of the fornix fibers may represent early ischemic injury in this population.

Effect of white matter lesions on manual dexterity in healthy middle-aged persons

OBJECTIVES

We hypothesized that integrated motor-visual functions measured by manipulative manual dexterity are affected by white matter lesion (WML) burden as measured on cranial MRI across relevant brain regions in subjects at risk of preclinical occult vascular disease.

METHODS

A real-time cross-sectional study of healthy subjects aged 29 to 74 years with a family history of early-onset coronary artery disease (n = 714; mean age, 51 ± 11 years; mean education, 14 ± 3 years; 42% male; 38% black) were identified from probands with coronary artery disease diagnosed before age 60 years. WMLs on 3-tesla brain MRI and Grooved Pegboard scores were measured.

RESULTS

WMLs were observed at all ages. Mean pegboard scores were 108 ± 18, similar to normal populations. In unadjusted analysis, WMLs and pegboard scores were significantly correlated by region (total WMLs, r = 0.34, p = 0.0001; frontal [r = 0.34, p < 0.0001], insula [r = 0.31, p < 0.0001], parietal [r = 0.31, p < 0.0001], and temporal [r = 0.17, p < 0.0001]). In multivariate analysis predicting (log) pegboard score adjusted for age, sex, race, education, regional or total volumes, and familial non-independence, total WML volume (p = 5.79E - 05) and regional WML volumes (p < 0.01) retained statistical significance in all but the youngest age quartile (29-43 years).

CONCLUSIONS

Greater WML volumes in different brain regions are associated with higher pegboard scores (worse performance) independent of age, sex, race, education, and total or regional volumes. This suggests that small vessel cerebrovascular disease may be present in healthy individuals in a preclinical state with measurable impact on complex integrative functions in individuals with excess risk of clinical vascular disease.

Abstract 42: Haptoglobin 2-2 Phenotype Is associated with Cerebral Salt Wasting Syndrome in Aneurysmal Subarachnoid Hemorrhage

INTRODUCTION: The Haptoglobin (Hp) phenotype has been shown to be a predictor of clinical outcomes in cerebrovascular disorders. We sought to determine if the Hp phenotype was predictive of cerebral salt wasting (CSW) following aneurysmal subarachnoid hemorrhage (SAH).

METHODS: Patients admitted with a diagnosis of SAH were divided into three groups based on their genetically determined Hp phenotype: 1-1, 2-1, and 2-2. Outcome measures included CSW, delayed cerebral infarction (DCI) and favorable outcome -Glasgow Outcome score (GOS) of 4-5 at 30 days. CSW was diagnosed by a clinician, and met the following criteria: hyponatremia 4 liters in 12 hours with urine sodium > 40 mEq/L. Pearson’s Chi Square and Wilcoxon-Mann-Whitney tests were used for categorical and continuous variables respectively. Logistic regression was used to assess association between Hp phenotype and SAH outcomes.

RESULTS: A total of 133 patients were included in the study. The distribution of Hp phenotype was- Hp 1-1: 29 (21.8%), Hp 2-1: 57 (42.9%), Hp 2-2: 47 (35.3%). The three Hp subgroups did not differ in terms of demographic variables, comorbidities or SAH characteristics. CSW occurred in 1 patient (3.4%) with Hp 1-1, 8 (14.0%) with Hp 2-1 and 15 (31.9%) with Hp 2-2 (p=0.004). In the multivariate analysis adjusted for age, sex, race, Hunt-Hess score and hydrocephalus, Hp 2-2 was associated with CSW (OR: 4.94 CI: 1.78-17.43, p=0.013) but Hp 2-1 was not (OR: 2.92, CI: 0.56-4.95, p=0.150). There were no associations between Hp phenotypes and favorable outcomes or DCI. CSW correlated strongly with development of DCI (OR: 7.16, OR: 2.48-20.62, p<0.001).

CONCLUSIONS: Hp 2-2 phenotype was an independent predictor of cerebral salt wasting following SAH. There were no associations between Hp phenotype and DCI or good functional outcome.

Abstract 154: Heritability of Ischemic White Matter Lesions in a Family Population with Increased Susceptibility of Vascular Disease

Introduction: Ischemic strokes are more likely to occur in the subcortical region of the brain, and also cluster strongly in families. However, the extent to which ischemic white matter lesions (WML) are heritable in a high risk healthy population remains unknown. We thus examined the heritability of ischemic WML volumes in both the periventricular (PV) and subcortical (SC) brain regions in apparently healthy European American (EA) and African American (AA) families with increased susceptibility for vascular disease .

Methods: We measured traditional risk factors, and imaged the brains of 579 healthy first degree relatives of probands with early onset CAD prior to 60 years of age. PV and SC WML volumes were directly measured using 3T cranial MRI. The location and volume of lesions were characterized using standard automated software. Maximum-likelihood estimates of polygenic heritability were performed on the unadjusted and adjusted transformed WML traits with the use of variance components models in the ASSOC subroutine of SAGE.

Results: Heritability was analyzed in 359 EA from 122 pedigrees as well as in 220 AA from 75 pedigrees. Participants were 58% women, 37% AA; mean age 51.5±11 (range of 29-74 years). Adjusting for age, sex, systolic blood pressure, and intracranial volume we determined the heritability for total WML volumes in EA’s (h2=0.62, SE 0.135, p<0.00001), and AA (h2=0.16, SE 0.24, p=0.25); for PV WML in EA’s (h2=0.31, SE 0.145, p=0.00167) in AA’s (h2=0.037, SE 0.165, p=0.4118); and for SC WML in EA’s (h2=0.581, SE 0.166, p=0.0002) and AA’s (h2=0.582, SE 0.182, p=0.0007).

Conclusions: Total WML volumes were highly heritable in EA, as were both PV, and SC WML volumes. In AA, only SC WML volumes were significantly heritable. In general, heritability estimates where greater for the SC than for the PV WML volumes. These findings suggest a heritable precursor state of stroke-related small vessel cerebrovascular disease in EA, generally greater for the subcortical region where subsequent strokes are more likely to occur, and a similar state only in the SC region in AA high risk healthy family members with susceptibility to vascular disease.

Presence of haptoglobin-2 allele is associated with worse functional outcomes after spontaneous intracerebral hemorrhage

OBJECTIVE

To determine if the haptoglobin (Hp) phenotype, which has been shown to be a predictor of clinical outcomes in cerebrovascular disorders, particularly subarachnoid hemorrhage, was predictive of functional outcomes after spontaneous intracerebral hemorrhage (ICH).

METHODS

Patients admitted with a diagnosis of ICH were prospectively included and divided into 3 groups based on their genetically determined Hp phenotype: 1-1, 2-1, and 2-2. Outcome measures included mortality and 30-day modified Rankin Scale scores. Demographics and outcomes were compared for each phenotype using multivariate linear regression analysis.

RESULTS

The study included 94 patients. The distribution of Hp phenotype was Hp 1-1, 12 (13%); Hp 2-1, 46 (49%); and Hp 2-2, 36 (38%). The 3 Hp subgroups did not differ in terms of demographic variables, comorbidities, or ICH characteristics. There was a nonsignificant trend toward increased mortality in Hp 2-1 and Hp 2-2 compared with Hp 1-1, with mortality of 8% in Hp 1-1, 17% in Hp 2-1, and 25% in Hp 2-2 (P = 0.408). In the regression model adjusted for confounders, Hp 2-1 (odds ratio = 0.05, 95% confidence interval = 0.01-0.47, P < 0.001) and Hp 2-2 phenotypes (odds ratio = 0.14, 95% confidence interval = 0.02-0.86, P = 0.045) had significantly lower odds of modified Rankin Scale scores 0-2 compared with Hp 1-1.

CONCLUSIONS

After ICH, individuals with the Hp-2 allele (2-1 and 2-2) had worse functional outcomes than individuals with the Hp-1 allele (Hp 1-1). There was a nonsignificant association between Hp phenotype and mortality. Larger prospective studies with better surrogates of ICH outcomes are warranted.

Extreme deep white matter hyperintensity volumes are associated with African American race

BACKGROUND

African Americans (AAs) have a higher prevalence of extreme ischemic white matter hyperintensities (WMHs) on magnetic resonance imaging (MRI) than do European Americans (EAs) based on the Cardiovascular Health Study (CHS) score. Ischemic white matter disease, limited to the deep white matter, may be biologically distinct from disease in other regions and may reflect a previously observed trend toward an increased risk of subcortical lacunar infarcts in AAs. We hypothesized that extreme deep WMH volume (DWMV) or periventricular volume (PV) may also have a higher prevalence in AAs. Thus, we studied extreme CHS scores and extreme DWMV and PV in a healthy population enriched for cardiovascular disease risk factors.

METHODS

We imaged the brains of 593 subjects who were first-degree relatives of probands with early onset coronary disease prior to 60 years of age. WMHs were manually delineated on 3-tesla cranial MRI by a trained radiology reader; the location and volume of lesions were characterized using automated software. DWMV and PV were measured directly with automated software, and the CHS score was determined by a neuroradiologist. Volumes were characterized as being in the upper 25% versus lower 75% of total lesion volume. Volumes in the upper versus the remaining quartiles were examined for AA versus EA race using multiple logistic regression (generalized estimating equations adjusted for family relatedness) and adjusted for major vascular disease risk factors including age ≥55 years versus <55, sex, current smoking, obesity, hypertension, diabetes and low-density lipoprotein >160 mg/dl.

RESULTS

Participants were 58% women and 37% AAs, with a mean age of 51.5 ± 11.0 years (range, 29-74 years). AAs had significantly higher odds of having extreme DWMVs (odds ratio, OR, 1.8; 95% confidence interval, CI, 1.2-2.9; p = 0.0076) independently of age, sex, hypertension and all other risk factors. AAs also had significantly higher odds of having extreme CHS scores ≥3 (OR, 1.3; 95% CI, 1.1-3.6; p = 0.025). Extreme PV was not significantly associated with AA race (OR, 1.3; 95% CI, 0.81-2.1; p = 0.26).

CONCLUSIONS

AAs from families with early-onset cardiovascular disease are more likely to have extreme DWMVs (a subclinical form of cerebrovascular disease) and an extreme CHS score, but not extreme PV, independently of age and other cardiovascular disease risk factors. These findings suggest that this AA population is at an increased risk for DWMV and may be at an increased risk for future subcortical stroke. Longitudinal studies are required to see if DWMV is predictive of symptomatic subcortical strokes in this population.

Abstract 43: Increased Activation of Inflammatory Genes in Monocytes of Healthy People with Ischemic White Matter Disease

Introduction: White matter hyperintensities (WMH) on MRI represent small vessel ischemic cerebrovascular disease. Greater WMH burden is associated with higher levels of circulating inflammatory cytokines in persons > 65 years with dementia, suggesting a pro-inflammatory vascular process. We hypothesized that middle-aged, asymptomatic, apparently healthy high risk people with high WMH burden would demonstrate increased inflammatory gene expression in monocytes analyzed with microarray.

Methods: Subjects (N=70) were identified from a larger MRI study in 593 healthy family members of persons with early-onset CAD (< 60 years). We obtained monocytes and examined gene expression in all subjects (mean age 58.1 ± 10 years, range 30-73; 55% female; 36% African American). These included 35 subjects with the greatest WMH burden using volumetric methods in the larger study, and 35 unrelated age-sex-race matched controls with the lowest WMH burden. Monocyte mRNA was analyzed on Illumina Human HT12 v4 microarrays. We performed unsupervised principal component analysis (PCA) followed by ANOVA between high and low WMH groups. Genes with 2 SD differences in expression between groups were included for Gene Ontology permutation analysis using 1000 permutations within “GoMiner”. Only genes with the lowest false discovery rate (FDR) were summarized.

Results: PCA identified no significant clustering. A total of 1,315 genes were included in gene ontology analysis and resulted in 10 ontological categories with an FDR<0.01%. This included 164 genes all showing greater expression in the high WMH group. These were key inflammatory genes, such as tumor necrosis factor (TNF), interleukin-6 (IL-6), interleukin-8 (IL-8), toll like receptor 5 and 7 (TLR5, TLR7) and integrin alpha 5 and M (ITGA5, ITGAM).

Conclusions: Gene microarray ontological analysis of monocytes in healthy middle aged high risk people with greater WMH burden shows increased activation of genes of known innate inflammatory pathways. These findings likely reflect greater pro-inflammatory processes in persons with greater WMH, consistent with the presence of inflammation-mediated occult small vessel cerebrovascular disease in a healthy middle-aged population at increased risk for vascular diseases.

Abstract 109: Manipulative Dexterity is Associated with Occult White Matter Ischemic Lesions in Healthy Asymptomatic Persons at Increased Risk for Cardiovascular Disease

Introduction: Persons with a family history of early-onset coronary artery disease (CAD) have an excess risk of stroke and CAD. White matter lesions (WML) on MRI represent small vessel ischemic cerebrovascular disease and are associated with incident stroke and neurocognitive decline with age. We hypothesized manipulative manual dexterity, an integration of fine motor, visual spatial, and cognition function, may be affected by increased WML burden in task-relevant brain regions across age ranges in persons at risk for pre-clinical occult vascular disease. We tested this in a large population with a family history of early CAD.

Methods: Healthy 29-74 year old subjects (N=714; mean age 51± 11 years; mean education 14 ± 3 years; 42% male, 38% Black) were identified from probands with CAD <60 years. WML location and volumes were measured on 3T FLAIR MRI. Manipulative manual dexterity was measured with standardized timed grooved pegboard test. Left and right pegboard scores were averaged.

Results: WML were observed in all age groups; mean overall pegboard scores were 108±18, and were within reference norms. In unadjusted analysis, pegboard scores were highly correlated in the expected direction with total WML volumes, r=0.34, p=<.0001; subcortical volumes r=0.30, <.0001 periventricular volumes r=0.31, <.0001; and with most regional WML volumes; frontal 0.34, <.0001; insula r=0.31, p<.0001, parietal r=0.31, p<.0001, and temporal volumes r=0.17, p <.0001. In separate multivariate regression analyses predicting (log) pegboard score adjusted for age, sex, race, education and nonindependence of families (GEE), total WML volume became more statistically significant ( p=5.79E-05) while other regions retained statistical significance, p< 0.01.

Conclusions: Our findings in a large population-based sample with a family history of early CAD confirm that greater WML volumes in multiple brain locations are associated with higher pegboard scores (worse performance) independent of age, sex, race, and education. This suggests that small vessel cerebrovascular disease is present in an early preclinical state and that WML volumes impact manipulative manual dexterity in healthy middle-aged and younger individuals with excess risk for clinical vascular disease.

Management of intracerebral pressure in the neurosciences critical care unit

Management of intracranial pressure in neurocritical care remains a potentially valuable target for improvements in therapy and patient outcomes. Surrogate markers of increased intracranial pressure, invasive monitors, and standard therapy, as well as promising new approaches to improve cerebral compliance are discussed, and a current review of the literature addressing this metric in neuroscience critical care is provided.

Strategies for the use of mechanical ventilation in the neurologic intensive care unit

Mechanical ventilation in neurologically injured patients presents unique challenges. Patients with acute neurologic injuries may require mechanical ventilation for reasons beyond respiratory failure. There is also a subset of pulmonary pathologic abnormality directly associated with neurologic injuries. Balancing the need to maintain brain oxygenation, cerebral perfusion, and control of intracranial pressure can be in conflict with concurrent ventilator strategies aimed at lung protection. Weaning and liberation from mechanical ventilation also require special considerations. These issues are examined in the ventilator management of the neurologically injured patient.

AUTOMATED ANATOMICAL LABELING OF THE CEREBRAL ARTERIES USING BELIEF PROPAGATION

Labeling of cerebral vasculature is important for characterization of anatomical variation, quantification of brain morphology with respect to specific vessels, and inter-subject comparisons of vessel properties and abnormalities. We propose an automated method to label the anterior portion of cerebral arteries using a statistical inference method on the Bayesian network representation of the vessel tree. Our approach combines the likelihoods obtained from a random forest classifier trained using vessel centerline features with a belief propagation method integrating the connection probabilities of the cerebral artery network. We evaluate our method on 30 subjects using a leave-one-out validation, and show that it achieves an average correct vessel labeling rate of over 92%.

Protein biomarkers in patients with subarachnoid hemorrhage, vasospasm, and delayed ischemic neurological deficits

Aneurysmal subarachnoid hemorrhage (aSAH) is a devastating neurological disease. It has many sequelae, including vasospasm and delayed ischemic neurological deficits (DINDs). We explored the blood proteome in patients with aSAH using transcranial Doppler (TCD) velocity as a guide to patients who are at risk for symptomatic vasospasm and DIND. Blood was drawn on all days that patients were observed in the neurocritical care unit (NCCU) after aSAH. A team of neurologists and neurosurgeons identified patients with clinical evidence of vasospasm and DIND. Serum was fractionated using protein chips and surface-enhanced laser desorption and ionization time-of-flight mass spectrometry (SELDI-TOF MS). We detected a pattern of protein expression associated with those at risk for elevated TCD velocities by day 8, compared with blood collected in the presymptomatic stage (days 1-3). We further analyzed serum using pooled samples from study entry to the time of elevated TCD velocities using a protein microarray that analyzed 500 human proteins thematically oriented toward inflammation. After identifying several candidates with elevated concentrations in the pooled samples, we then used reverse protein arrays to quantitate the concentration of potential candidate proteins in the individual samples. Proteins with significantly elevated concentrations included apolipoprotein-E, apolipoprotein-A, serum amyloid protein-4, and serum amyloid protein-P. Future studies in larger sample populations are needed to evaluate these biomarkers further as representative of biosystems involved in vasospasm and DIND or as potential biomarkers predictive of risk associated with disease.

The role of neurocritical care: a brief report on the survey results of neurosciences and critical care specialists

BACKGROUND

Neurocritical care is a new subspecialty field in medicine that intersects with many of the neuroscience and critical care specialties, and continues to evolve in its scope of practice and practitioners. The objective of this study was to assess the perceived need for and roles of neurocritical care intensivists and neurointensive care units among physicians involved with intensive care and the neurosciences.

METHODS

An online survey of physicians practicing critical care medicine, and neurology was performed during the 2008 Leapfrog initiative to formally recognize neurocritical care training.

RESULTS

The survey closed in July 2009 and achieved a 13% response rate (980/7524 physicians surveyed). Survey respondents (mostly from North America) included 362 (41.4%) neurologists, 164 (18.8%) internists, 104 (11.9%) pediatric intensivists, 82 (9.4%) anesthesiologists, and 162 (18.5%) from other specialties. Over 70% of respondents reported that the availability of neurocritical care units staffed with neurointensivists would improve the quality of care of critically ill neurological/neurosurgical patients. Neurologists were reported as the most appropriate specialty for training in neurointensive care by 53.3%, and 57% of respondents responded positively that neurology residency programs should offer a separate training track for those interested in neurocritical care.

CONCLUSION

Broad level of support exists among the survey respondents (mostly neurologists and intensivists) for the establishment of neurological critical care units. Since neurology remains the predominant career path from which to draw neurointensivists, there may be a role for more comprehensive neurointensive care training within neurology residencies or an alternative training track for interested residents.

Biomarker discovery in serum from patients with carotid atherosclerosis

BACKGROUND

Blood-based biomarkers of atherosclerosis have been used to identify patients at high risk for developing stroke. We hypothesized that patients with carotid artery disease would have a distinctive proteomic signature in blood as compared to a healthy control population without carotid artery disease. In order to discover protein biomarkers associated with increased atherosclerotic risk, we used two different strategies to identify biomarkers from patients with clinically defined atherosclerosis who were undergoing endarterectomy for atherosclerotic carotid artery disease. These patients were compared with healthy matched controls.

METHODS

Serum was obtained from patients undergoing endarterectomy (EA; n = 38) and compared to a group of age-matched healthy controls (n = 40). Serum was fractionated using anion exchange chromatography and three different surface-enhanced laser desorption/ionization (SELDI) chip surfaces and then evaluated with mass spectrometry (MS) and two-dimensional difference gel electrophoresis (2D-DIGE).

RESULTS

A random forest (RF) analysis of the SELDI-MS protein peak data distinguished these two groups with 69.2% sensitivity and 73.2% specificity. Four unique SELDI peaks (4.2, 4.4, 16.7 and 28 kDa, all p< 0.01) showed the greatest influence in the RF model. The EA patients with a history of prior clinical atherosclerotic plaque rupture manifested as either stroke or transient ischemic attack (symptomatic; n = 16) were compared to patients with carotid atherosclerosis but no clinical evidence of plaque rupture (asymptomatic; n = 22). Analysis of the SELDI spectra did not separate these two patient subgroups. A subgroup analysis using 2D-DIGE images obtained from albumin-depleted serum comparing symptomatic (n = 10) to asymptomatic EA patients (n = 10) found 4 proteins that were differentially expressed (p < 0.01) in the symptomatic patients. These proteins were identified as α(1)-antitrypsin, haptoglobin and vitamin D binding protein that were downregulated and α(2)-glycoprotein precursor that was upregulated in the symptomatic EA group.

CONCLUSIONS

SELDI-MS data analysis of fractionated serum suggests that a distinct protein signature exists in patients with carotid atherosclerosis compared to age-matched healthy controls. Identification of 4 proteins in a subset of patients with symptomatic and asymptomatic carotid atherosclerosis suggests that these and other protein biomarkers may assist in identifying high-risk patients with carotid atherosclerosis.