Small vessel disease burden and functional brain connectivity in mild cognitive impairment

Background

The role of small vessel disease in the development of dementia is not yet completely understood. Functional brain connectivity has been shown to differ between individuals with and without cerebral small vessel disease. However, a comprehensive measure of small vessel disease quantifying the overall damage on the brain is not consistently used and studies using such measure in mild cognitive impairment individuals are missing.

Method

Functional brain connectivity differences were analyzed between mild cognitive impairment individuals with absent or low (n = 34) and high (n = 34) small vessel disease burden using data from the Parelsnoer Institute, a Dutch multicenter study. Small vessel disease was characterized using an ordinal scale considering: lacunes, microbleeds, perivascular spaces in the basal ganglia, and white matter hyperintensities. Resting state functional MRI data using 3 Tesla scanners was analyzed with group-independent component analysis using the CONN toolbox.

Results

Functional connectivity between areas of the cerebellum and between the cerebellum and the thalamus and caudate nucleus was higher in the absent or low small vessel disease group compared to the high small vessel disease group.

Conclusion

These findings might suggest that functional connectivity of mild cognitive impairment individuals with low or absent small vessel disease burden is more intact than in mild cognitive impairment individuals with high small vessel disease. These brain areas are mainly responsible for motor, attentional and executive functions, domains which in previous studies were found to be mostly associated with small vessel disease markers. Our results support findings on the involvement of the cerebellum in cognitive functioning.

Patterns of Regional Brain Atrophy and Brain Aging in Middle- and Older-Aged Adults With Type 1 Diabetes

Importance

Little is known about structural brain changes in type 1 diabetes (T1D) and whether there are early manifestations of a neurodegenerative condition like Alzheimer disease (AD) or evidence of premature brain aging.

Objective

To evaluate neuroimaging markers of brain age and AD-like atrophy in participants with T1D in the Diabetes Control and Complications Trial (DCCT)/Epidemiology of Diabetes Interventions and Complications (EDIC) study, identify which brain regions are associated with the greatest changes in patients with T1D, and assess the association between cognition and brain aging indices.

Design, Setting, and Participants

This cohort study leveraged data collected during the combined DCCT (randomized clinical trial, 1983-1993) and EDIC (observational study, 1994 to present) studies at 27 clinical centers in the US and Canada. A total of 416 eligible EDIC participants and 99 demographically similar adults without diabetes were enrolled in the magnetic resonance imaging (MRI) ancillary study, which reports cross-sectional data collected in 2018 to 2019 and relates it to factors measured longitudinally in DCCT/EDIC. Data analyses were performed between July 2020 and April 2022.

Exposure

T1D diagnosis.

Main Outcomes and Measures

Psychomotor and mental efficiency were evaluated using verbal fluency, digit symbol substitution test, trail making part B, and the grooved pegboard. Immediate memory scores were derived from the logical memory subtest of the Wechsler memory scale and the Wechsler digit symbol substitution test. MRI and machine learning indices were calculated to predict brain age and quantify AD-like atrophy.

Results

This study included 416 EDIC participants with a median (range) age of 60 (44-74) years (87 of 416 [21%] were older than 65 years) and a median (range) diabetes duration of 37 (30-51) years. EDIC participants had consistently higher brain age values compared with controls without diabetes, indicative of approximately 6 additional years of brain aging (EDIC participants: β, 6.16; SE, 0.71; control participants: β, 1.04; SE, 0.04; P < .001). In contrast, AD regional atrophy was comparable between the 2 groups. Regions with atrophy in EDIC participants vs controls were observed mainly in the bilateral thalamus and putamen. Greater brain age was associated with lower psychomotor and mental efficiency among EDIC participants (β, -0.04; SE, 0.01; P < .001), but not among controls.

Conclusions and Relevance

The findings of this study suggest an increase in brain aging among individuals with T1D without any early signs of AD-related neurodegeneration. These increases were associated with reduced cognitive performance, but overall, the abnormal patterns seen in this sample were modest, even after a mean of 38 years with T1D.

Cardiac dysfunction in relation to vascular brain injury, cognitive impairment and depressive symptoms; The Heart-Brain Connection Study

Introduction

Cardiovascular disease is an independent contributor to cognitive impairment. With an imminent rise in chronic cardiovascular disease, a better understanding of its effects on brain health is warranted. Impaired blood flow to the brain is one of the main hypothesized mechanisms linking cardiovascular disease with abnormal brain aging.

Purpose

To investigate relations between (subclinical) cardiac dysfunction and vascular brain injury, cognitive impairment and depressive symptoms, with a side-by-side comparison of cardiac biomarkers and imaging parameters.

Methods

Multicenter, cross-sectional, observational cohort study among 559 participants: 431 with manifest cardiovascular disease (heart failure [HF], carotid occlusive disease or vascular cognitive impairment) and 128 control participants, all without dementia. Participants underwent 3T heart-brain MRI and cognitive testing. Determinants were cardiac biomarkers (NT-proBNP and high-sensitive Troponin-I) and left ventricular (LV) functional parameters by MRI (LV ejection fraction, cardiac output, LV global function index). Outcome measures were cerebral small vessel disease (CSVD) by MRI (presence of white matter hyperintensities, microbleeds, lacunar infarcts or perivascular spaces), CSVD score (0–4), cognitive impairment in ≥1 domain (memory, language, attention-psychomotor speed and executive functioning) and depressive symptoms (Geriatric Depression Scale-15 score &gt;5). Interaction analyses were used to investigate effect modification by patient group; results are reported pooled or stratified accordingly.

Results

In patients with cardiovascular disease and controls, but not in those with manifest HF, LV functional parameters were associated with CSVD and cognitive impairment, with the following associations: LVEF &lt;50% with CSVD (OR 4.67 [1.37–15.95]) and CSVD score (RR 1.38 [1.06–1.81]); LV global function index with CSVD (OR 0.71 [0.58–0.86]), CSVD score (RR 0.90 [0.84–0.96]) and cognitive impairment (OR 0.84 [0.72–0.97]). LV global function index (OR 0.82 [0.71–0.95]) and cardiac output (OR 0.81 [0.71–0.93]) were also associated with depressive symptoms in all. These relations were independent from age, sex, hypertension, diabetes, waist-hipratio, history of ischemic heart disease, transient ischemic attack or stroke. Cardiac biomarkers were univariably associated with brain outcome measures, but not in multivariable analysis.

Conclusion

This study indicates that subclinical cardiac dysfunction, as assessed by cardiovascular MRI, is independently associated with vascular brain injury, cognitive impairment and depressive symptoms. Of all parameters, LV global function index showed the most robust relations, indicating that global cardiac performance is more closely related to poorer brain outcome than merely LV systolic function. In those with clinically manifest HF, the severity of cardiac dysfunction was related to depressive symptoms but not to other brain outcome measures.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): The Netherlands CardioVascular Research Initiative; The Dutch Heart Foundation

Cerebral hemodynamics during atrial fibrillation: computational fluid dynamics (CFD) analysis of lenticulostriate arteries using 7T high-resolution magnetic resonance imaging

Background

Lenticulostriate arteries (LSAs) are small perforating arteries (0.1–1 mm diameter), perpendicularly departing from middle cerebral artery (MCA) and supplying blood flow to important cerebral subcortical and basal ganglia areas. LSAs are involved in silent strokes and cerebral small vessel disease, potentially leading to cognitive decline and vascular dementia. There is growing evidence that atrial fibrillation (AF), the most common cardiac arrhythmia, increases the risk of dementia even in the absence of clinical strokes. AF also increase the risk of small vessel disease. AF may alter deep cerebral hemodynamics per se, however no data exists regarding a possible impact of AF on MCA-LSA branching sites hemodynamics.

Purpose

To use computational fluid dynamics (CFD) analysis to study the hemodynamics of LSAs-MCA branching sites.

Methods

7T high-resolution magnetic resonance imaging (HR-MRI) brain scans (Figure 1, panel a) were used to derive detailed geometrical models of LSAs-MCA branching sites. CFD analysis was then conducted, simulating AF conditions as well as sinus rhythm (SR), at different ventricular rates (from 50 to 130 bpm).

Results

Geometrical models were retrieved from HR-MRI scans of 7 patients. By means of the most significant metrics, such as wall shear stress (WSS; Figure 1, panel b), wall shear stress gradient (WSSG), and flow velocity (FV), a comparison between SR and AF was performed.

Conclusion

CFD analysis of LSAs-MCA branching sites using geometrical models derived from HR-MRI brain scans was feasible and allows to quantify the impact of AF on these critical ramifications of the MCA.

Funding Acknowledgement

Type of funding sources: None.

Brain Structure Among Middle-aged and Older Adults With Long-standing Type 1 Diabetes in the DCCT/EDIC Study

OBJECTIVE

Individuals with type 1 diabetes mellitus (T1DM) are living to ages when neuropathological changes are increasingly evident. We hypothesized that middle-aged and older adults with long-standing T1DM will show abnormal brain structure in comparison with control subjects without diabetes.

RESEARCH DESIGN AND METHODS

MRI was used to compare brain structure among 416 T1DM participants in the Epidemiology of Diabetes Interventions and Complications (EDIC) study with that of 99 demographically similar control subjects without diabetes at 26 U.S. and Canadian sites. Assessments included total brain (TBV) (primary outcome), gray matter (GMV), white matter (WMV), ventricle, and white matter hyperintensity (WMH) volumes and total white matter mean fractional anisotropy (FA). Biomedical assessments included HbA1c and lipid levels, blood pressure, and cognitive assessments of memory and psychomotor and mental efficiency (PME). Among EDIC participants, HbA1c, severe hypoglycemia history, and vascular complications were measured longitudinally.

RESULTS

Mean age of EDIC participants and control subjects was 60 years. T1DM participants showed significantly smaller TBV (least squares mean ± SE 1,206 ± 1.7 vs. 1,229 ± 3.5 cm3, P < 0.0001), GMV, and WMV and greater ventricle and WMH volumes but no differences in total white matter mean FA versus control subjects. Structural MRI measures in T1DM were equivalent to those of control subjects who were 4-9 years older. Lower PME scores were associated with altered brain structure on all MRI measures in T1DM participants.

CONCLUSIONS

Middle-aged and older adults with T1DM showed brain volume loss and increased vascular injury in comparison with control subjects without diabetes, equivalent to 4-9 years of brain aging.

Cerebral Blood Flow in Patients with Severe Aortic Valve Stenosis Undergoing Transcatheter Aortic Valve Implantation

BACKGROUND

Transcatheter aortic valve implantation (TAVI) is a minimally invasive, life‐saving treatment for patients with severe aortic valve stenosis that improves quality of life. We examined cardiac output and cerebral blood flow in patients undergoing TAVI to test the hypothesis that improved cardiac output after TAVI is associated with an increase in cerebral blood flow.

DESIGN

Prospective cohort study.

SETTING

European high‐volume tertiary multidisciplinary cardiac care.

PARTICIPANTS

Thirty‐one patients (78.3 ± 4.6 years; 61% female) with severe symptomatic aortic valve stenosis.

MEASUREMENTS

Noninvasive prospective assessment of cardiac output (L/min) by inert gas rebreathing and cerebral blood flow of the total gray matter (mL/100 g per min) using arterial spin labeling magnetic resonance imaging in resting state less than 24 hours before TAVI and at 3‐month follow‐up. Cerebral blood flow change was defined as the difference relative to baseline.

RESULTS

On average, cardiac output in patients with severe aortic valve stenosis increased from 4.0 ± 1.1 to 5.4 ± 2.4 L/min after TAVI (P = .003). The increase in cerebral blood flow after TAVI strongly varied between patients (7% ± 24%; P = .41) and related to the increase in cardiac output, with an 8.2% (standard error = 2.3%; P = .003) increase in cerebral blood flow per every additional liter of cardiac output following the TAVI procedure.

CONCLUSION

Following TAVI, there was an association of increase in cardiac output with increase in cerebral blood flow. These findings encourage future larger studies to determine the influence of TAVI on cerebral blood flow and cognitive function.

Microbleeds colocalize with enlarged juxtacortical perivascular spaces in amnestic mild cognitive impairment and early Alzheimer's disease: A 7 Tesla MRI study

MRI-visible perivascular spaces (PVS) in the semioval centre are associated with cerebral amyloid angiopathy (CAA), but it is unknown if PVS co-localize with MRI markers of CAA. To examine this, we assessed the topographical association between cortical cerebral microbleeds (CMBs) - as an indirect marker of CAA - and dilatation of juxtacortical perivascular spaces (jPVS) in 46 patients with amnestic mild cognitive impairment (aMCI) or early Alzheimer's disease (eAD). The degree of dilatation of jPVS <1 cm around each cortical CMBs was compared with a similar reference site (no CMB) in the contralateral hemisphere, using a 4-point scale. Also, jPVS dilatation was compared between patients with and without cortical CMBs. Eleven patients (24%) had cortical CMBs [total=35, median=1, range=1-14] of whom five had >1 cortical CMBs. The degree of jPVS dilatation was higher around CMBs than at the reference sites [Wilcoxon signed rank test, Z = 2.2, p = 0.03]. Patients with >1 cortical CMBs had a higher degree of jPVS dilation [median=2.2, IQR = 1.8-2.3] than patients without cortical CMBs [median=1.4, IQR = 1.0-1.8], p = 0.02. We found a topographical association between a high degree of jPVS dilatation and cortical CMBs, supporting a common underlying pathophysiology - most likely CAA.

Cortical cerebral microinfarcts predict cognitive decline in memory clinic patients

Cortical cerebral microinfarcts (CMIs) - a novel MRI marker of cerebral vascular pathology have been linked with dementia and impaired cognition in cross-sectional studies. However, it is unknown if cortical CMIs are an indicator of further cognitive decline. We sought to examine whether baseline cortical CMIs predict cognitive decline in a prospective memory-clinic setting. A total of 313 patients with baseline 3T MRI scans and at least two neuropsychological assessments obtained a minimum of one year apart were recruited. Cortical CMIs were graded on baseline MRI according to a validated protocol. The Montreal Cognitive Assessment (MoCA) and a detailed neuropsychological battery were used to assess cognition. Patients with increased cortical CMIs showed greater decline in MoCA and global cognition per year. Patients with > 2 cortical CMIs decline on average by 2 scores on MoCA and 0.5 on global cognition at year two which corresponds to 109.8% and 184.5% greater decline when compared to those without CMIs. Furthermore, cortical CMIs at baseline were associated with accelerated decline in memory and language domains. Similar associations were observed when analysis was restricted to demented patients. Cortical CMIs together with other cerebrovascular disease markers can be used to design clinical trials in vascular cognitive impairment.

Cognitive dysfunction in diabetes: how to implement emerging guidelines

Cognitive dysfunction, including mild cognitive impairment and dementia, is increasingly recognised as an important comorbidity and complication of diabetes that affects an individual's well-being and diabetes management, and is associated with diabetes treatment-related complications. Recent guidelines therefore recommend screening for cognitive impairment in older individuals with diabetes. In addition, these guidelines suggest that glucose-lowering treatment should be tailored in those diagnosed with cognitive impairment, to reduce the risk of hypoglycaemia and improve treatment adherence. This review gives an overview of cognitive dysfunction in people with diabetes, briefly describing the clinical features of different stages of cognitive dysfunction and their epidemiology. In particular, it addresses essential additional steps that need to be taken to fully implement the emerging guidelines on screening and management of cognitive dysfunction in diabetes into daily practice.

P3714Cerebral blood flow and cognitive functioning in the heart-brain axis

Background

Recent studies suggest that cardiovascular disease and dementia are closely related, which led to the concept of a “heart-brain axis”. Dysfunction in any component of the heart-brain axis could be a risk factor for the development of brain damage and consequently to the development of cognitive impairment. In the Heart-Brain study, we focus on vascular cognitive impairment (VCI), symptomatic carotid occlusive disease (COD) and heart failure (HF) as three extreme phenotypes of haemodynamic dysfunction in different components of the heart-brain axis (i.e. heart – carotids – brain). We compared values of cerebral blood flow (CBF), measured with arterial spin labeling (ASL) between patients with HF, COD and VCI and investigated the association between CBF and cognitive functioning.

Methods

We included 442 participants (129 VCI; 75 COD; 124 HF; and 114 controls) from the Heart-Brain Study (67±9 yrs; 38% F; MMSE 28±2). We used 3T pseudo-continuous ASL to estimate whole-brain and regional partial volume-corrected CBF. Using a standardized neuropsychological assessment, we measured global cognitive functioning and four cognitive domains. Compound z-scores were constructed for each cognitive domain. We investigated associations using linear regression analyses, adjusted for age, sex, education, center and diagnosis. Subsequently, we stratified for diagnosis.

Results

Whole-brain and regional CBF values were lowest in patients with COD, followed by VCI and HF, compared to controls. Global cognitive functioning was lowest in patients with VCI, followed by COD and HF, compared to controls. Overall, we found hardly any association between whole-brain or regional CBF values and cognitive functioning (standardized beta [stb] = 0.00–0.10, p>0.05). Subsequent stratification for diagnosis showed no association between whole-brain or regional CBF and cognitive functioning in any participant group.

Conclusions

Our results suggest that reduced CBF is not the major explanatory factor underlying impaired cognitive functioning in patients with disorders along the heart-brain axis. The predisposition of cognitive impairment in these patients is likely to be driven by other (haemodynamic) mechanisms than CBF.

Acknowledgement/Funding

We acknowledge the support of the Netherlands CardioVascular Research Initiative: the Dutch Heart Foundation (CVON 2012-06 Heart Brain Connection), Du

6071Extent of hypertensive exposure in relation to vascular brain injury and cognitive impairment using heart-brain magnetic resonance imaging; The Heart-Brain Connection Study

Background

Preserving brain health into advanced age has become one of the great challenges of modern medicine. Hypertension is highly prevalent and considered an independent contributor to cognitive impairment. Vascular brain injury, induced by exposure of the cerebral microcirculation to increased pressure and pulsatility, is the hypothesized link between hypertension and cognitive impairment. Hypertensive exposure can be assessed by cardiovascular magnetic resonance imaging markers, e.g. aortic stiffness by pulse wave velocity (PWV), left ventricular mass index (LVMi) and left ventricular (LV) concentricity by mass-to-volume ratio.

Purpose

To investigate the extent of hypertensive exposure in relation to cerebral small vessel disease (CSVD) and cognitive impairment, using heart-brain magnetic resonance imaging.

Methods

We included 559 participants aged 68±9 years from the Heart-Brain Connection study, consisting of three patient groups (i.e. heart failure, vascular cognitive impairment and carotid occlusive disease) and controls. LVMi, LV mass-to-volume ratio, aortic PWV and CSVD were assessed by 3.0 T heart-brain magnetic resonance imaging. Impairment in ≥1 major cognitive domain was assessed by comprehensive neuropsychological testing. Effect modification for patient groups was investigated by interaction terms; results are reported pooled or stratified accordingly.

Results

Overall prevalence of CSVD was 68.7% and prevalence of cognitive impairment was 26.9%. Figure 1 provides a visual overview of hypertensive exposure markers in relation to brain outcome. Aortic PWV (odds ratio [OR] 1.17, p=0.003 in patient groups only), LVMi (OR in carotid occlusive disease 5.69, p=0.006; OR in other groups 1.30, p=0.017) and LV mass-to-volume ratio (OR 1.81, p<0.001) were all associated with CSVD. Both aortic PWV (OR 1.07, p=0.009) and LV mass-to-volume ratio (OR 1.27, p=0.007) were also associated with cognitive impairment. Relations were independent of sociodemographics and cardiac index, and mostly persisted after correction for systolic blood pressure or medical history of hypertension. The relations of hypertensive exposure markers with cognitive impairment were attenuated when presence of CSVD was added as co-variate, (indirectly) supporting the hypothesis that CSVD is the link between hypertension and cognitive impairment.

Figure 1

Conclusion

Hypertensive exposure markers were independently associated with CSVD and cognitive impairment. Our findings indicate that hypertensive exposure markers relate to brain structure and function beyond clinical blood pressure or medical history.

Acknowledgement/Funding

Netherlands Cardiovascular Research Initiative; Dutch Heart Foundation; NFU; ZonMW; KNAW

Strategic infarct location for post-stroke cognitive impairment: A multivariate lesion-symptom mapping study

Lesion location is an important determinant for post-stroke cognitive impairment. Although several 'strategic' brain regions have previously been identified, a comprehensive map of strategic brain regions for post-stroke cognitive impairment is lacking due to limitations in sample size and methodology. We aimed to determine strategic brain regions for post-stroke cognitive impairment by applying multivariate lesion-symptom mapping in a large cohort of 410 acute ischemic stroke patients. Montreal Cognitive Assessment at three to six months after stroke was used to assess global cognitive functioning and cognitive domains (memory, language, attention, executive and visuospatial function). The relation between infarct location and cognition was assessed in multivariate analyses at the voxel-level and the level of regions of interest using support vector regression. These two assumption-free analyses consistently identified the left angular gyrus, left basal ganglia structures and the white matter around the left basal ganglia as strategic structures for global cognitive impairment after stroke. A strategic network involving several overlapping and domain-specific cortical and subcortical structures was identified for each of the cognitive domains. Future studies should aim to develop even more comprehensive infarct location-based models for post-stroke cognitive impairment through multicenter studies including thousands of patients.

Abstract TP417: Cortical Microinfarcts on 3T MRI in Cerebral Amyloid Angiopathy: Associations With MRI Burden and Cognitive Dysfunction

Background: Cerebral amyloid angiopathy (CAA) causes vascular cognitive impairment, possibly due to ischemic lesions that are caused by impaired cerebral blood flow. Cerebral microinfarcts (CMIs) are small ischemic lesions that are found in CAA patients at autopsy.

Hypothesis: Cortical CMIs can be detected on in vivo 3T MR images in CAA and will correlate with markers of CAA-related vascular brain injury and cognitive function.

Methods: We analysed data from CAA cases and neurologically healthy controls participating in the Functional Assessment of Vascular Reactivity (FAVR) study. All participants underwent a standardized clinical, neuropsychological and 3T MR assessment. Cortical CMIs were rated according to standardized criteria, by a single rater blinded to clinical information.

Results: There were 36 CAA patients (mean age 73.0±9.0 years) and 22 healthy controls (69.0±8.3 years). Cortical CMIs were found in significantly more patients with CAA (50%) (median number: 1, range: 1-9) than in healthy controls (18%) ( p =0.02). In CAA, patients with cortical CMIs had higher white matter hyperintensity volumes (median 29.5 mL vs 13.0 mL, p =0.04) and cerebral microbleed counts (median 28 vs 5.5, p =0.049). CAA patients with cortical CMIs also showed lower occipital fMRI activation (median BOLD change 1.97% vs 2.57%, r =0.24, p =0.15) and worse memory performance (mean z -score -0.60 vs -0.05, p =0.12), although both effects were non-significant. No significant association of cortical CMIs with age, sex or vascular risk factors was found.

Conclusions: Cortical CMIs are frequently detected on 3T MRI in CAA. They relate to well-established ischemic and hemorrhagic MRI markers of CAA. Therefore in vivo cortical CMIs can be regarded as a new marker of CAA disease severity. Additional, larger studies are needed to determine the relationship between CMI and clinical outcomes in CAA.

[Risk of vitamin K antagonists in cases of cerebral microbleeds]

- Cerebral microbleeds are associated with a higher risk of intracerebral hemorrhage.- When microbleeds are detected, the possible underlying pathology should be considered; this includes cerebral amyloid angiopathy and other factors that increase the risk of haemorrhage, particularly hypertension. - No randomised trials have yet been conducted into haemorrhagic complications and cerebral infarctions in patients with microbleeds who take vitamin K antagonists. This means that it is not clear whether the intended prevention of cerebral infarctions outweighs the increased risk of haemorrhage associated with use of vitamin K antagonists by these patients.- When deciding whether or not an older patient should be given anticoagulants the following should be taken into consideration as well: comorbidities, polypharmacy, the risk of falls and the probability that the patient can be optimally titrated to vitamin K antagonists. - If there is an increased risk of intracerebral haemorrhage but anticoagulants are indicated, direct oral anticoagulants (DOACs) might be preferable to vitamin K antagonists in patients with a history of cerebral microbleeds.

Design of the ExCersion-VCI study: The effect of aerobic exercise on cerebral perfusion in patients with vascular cognitive impairment

There is evidence for a beneficial effect of aerobic exercise on cognition, but underlying mechanisms are unclear. In this study, we test the hypothesis that aerobic exercise increases cerebral blood flow (CBF) in patients with vascular cognitive impairment (VCI). This study is a multicenter single-blind randomized controlled trial among 80 patients with VCI. Most important inclusion criteria are a diagnosis of VCI with Mini-Mental State Examination ≥22 and Clinical Dementia Rating ≤0.5. Participants are randomized into an aerobic exercise group or a control group. The aerobic exercise program aims to improve cardiorespiratory fitness and takes 14 weeks, with a frequency of three times a week. Participants are provided with a bicycle ergometer at home. The control group receives two information meetings. Primary outcome measure is change in CBF. We expect this study to provide insight into the potential mechanism by which aerobic exercise improves hemodynamic status.

Hippocampal volume and the course of depressive symptoms over eight years of follow-up

OBJECTIVE

To estimate the association between hippocampal and total brain volume and the course of depressive symptoms over eight years of follow-up in patients with a history of vascular disease.

METHOD

Within the SMART-Medea study, 636 participants (62 ± 10 years) had a 1.5-tesla brain MRI obtaining hippocampal and total brain volumes. Depressive symptoms were assessed with the Patient Health Questionnaire-9 biannually during eight-year follow-up. Generalized estimating equation models with robust standard errors were used to assess the associations of hippocampal and total brain volumes with depressive symptoms during follow-up adjusting for age, sex, education, and intracranial volume. An interaction term between volume and time (6-month intervals) was included to examine whether the course of depressive symptoms differed according to hippocampal and total brain volume.

RESULTS

The mean PHQ-9 score was 2.8 ± 3.5. Smaller hippocampal volumes were associated with an increasing course of depressive symptom levels, while larger volumes were associated with decreasing levels (P-value interaction = 0.07). Smaller total brain volume was associated with consistently higher levels of depressive symptoms, but not with change in course of depressive symptoms (P-value interaction = 0.45).

CONCLUSION

Smaller hippocampal volume but not total brain volume is associated with poorer course of depressive symptoms over eight years of follow-up.

Temporal profile of body temperature in acute ischemic stroke: relation to infarct size and outcome

Background

High body temperatures after ischemic stroke have been associated with larger infarct size, but the temporal profile of this relation is unknown. We assess the relation between temporal profile of body temperature and infarct size and functional outcome in patients with acute ischemic stroke.

Methods

In 419 patients with acute ischemic stroke we assessed the relation between body temperature on admission and during the first 3 days with both infarct size and functional outcome. Infarct size was measured in milliliters on CT or MRI after 3 days. Poor functional outcome was defined as a modified Rankin Scale score ≥3 at 3 months.

Results

Body temperature on admission was not associated with infarct size or poor outcome in adjusted analyses. By contrast, each additional 1.0 °C in body temperature on day 1 was associated with 0.31 ml larger infarct size (95% confidence interval (CI) 0.04–0.59), on day 2 with 1.13 ml larger infarct size(95% CI, 0.83–1.43), and on day 3 with 0.80 ml larger infarct size (95% CI, 0.48–1.12), in adjusted linear regression analyses. Higher peak body temperatures on days two and three were also associated with poor outcome (adjusted relative risks per additional 1.0 °C in body temperature, 1.52 (95% CI, 1.17–1.99) and 1.47 (95% CI, 1.22–1.77), respectively).

Conclusions

Higher peak body temperatures during the first days after ischemic stroke, rather than on admission, are associated with larger infarct size and poor functional outcome. This suggests that prevention of high temperatures may improve outcome if continued for at least 3 days.

Assessment of blood flow velocity and pulsatility in cerebral perforating arteries with 7-T quantitative flow MRI

Thus far, blood flow velocity measurements with MRI have only been feasible in large cerebral blood vessels. High-field-strength MRI may now permit velocity measurements in much smaller arteries. The aim of this proof of principle study was to measure the blood flow velocity and pulsatility of cerebral perforating arteries with 7-T MRI. A two-dimensional (2D), single-slice quantitative flow (Qflow) sequence was used to measure blood flow velocities during the cardiac cycle in perforating arteries in the basal ganglia (BG) and semioval centre (CSO), from which a mean normalised pulsatility index (PI) per region was calculated (n = 6 human subjects, aged 23-29 years). The precision of the measurements was determined by repeated imaging and performance of a Bland-Altman analysis, and confounding effects of partial volume and noise on the measurements were simulated. The median number of arteries included was 14 in CSO and 19 in BG. In CSO, the average velocity per volunteer was in the range 0.5-1.0 cm/s and PI was 0.24-0.39. In BG, the average velocity was in the range 3.9-5.1 cm/s and PI was 0.51-0.62. Between repeated scans, the precision of the average, maximum and minimum velocity per vessel decreased with the size of the arteries, and was relatively low in CSO and BG compared with the M1 segment of the middle cerebral artery. The precision of PI per region was comparable with that of M1. The simulations proved that velocities can be measured in vessels with a diameter of more than 80 µm, but are underestimated as a result of partial volume effects, whilst pulsatility is overestimated. Blood flow velocity and pulsatility in cerebral perforating arteries have been measured directly in vivo for the first time, with moderate to good precision. This may be an interesting metric for the study of haemodynamic changes in aging and cerebral small vessel disease. © 2015 The Authors NMR in Biomedicine Published by John Wiley & Sons Ltd.

Relations between location and type of intracranial atherosclerosis and parenchymal damage

The aim of this study was to assess the relation between location and type of intracranial atherosclerosis (ICAS) and cortical microinfarcts (CMIs) and macroinfarcts in 18 patients presenting with ischemic stroke (n = 12) or transient ischemic attack (TIA) (n = 6) using 7 tesla MR imaging. The protocol included: 3D T2-weighted FLAIR and 3D T1-weighted Magnetization-Preparation Inversion Recovery Turbo Spin Echo sequence. ICAS lesions and infarcts were scored by two raters. The relation between ICAS lesions, calculated ratios of ICAS lesion characteristics, location, and infarcts were examined using linear regression analyses. A total number of 75 ICAS lesions (all patients), 101 CMIs (78% of patients), and 31 macroinfarcts (67% of patients) were found. Seventy-six and sixty-five percent of the CMIs and macroinfarcts, respectively, were found in the same vascular territory as the ICAS lesions (p = 0.977, p = 0.167, respectively). A positive correlation existed between the number of macroinfarcts and CMIs (p < 0.05). In patients with macroinfarcts, we found more concentric (p < 0.01) and diffuse (p < 0.05) type of ICAS lesions. A high prevalence of brain tissue lesions, both macroinfarcts and CMIs, were found in patients with ICAS. Macroinfarcts were found to be related to specific ICAS lesion types. The type of ICAS lesion seems to be promising as a marker for ICAS patients at higher risk of future infarcts.

Case-finding for cognitive impairment among people with Type 2 diabetes in primary care using the Test Your Memory and Self-Administered Gerocognitive Examination questionnaires: the Cog-ID study

AIM

To evaluate two cognitive tests for case-finding for cognitive impairment in older patients with Type 2 diabetes.

METHODS

Of 1243 invited patients with Type 2 diabetes, aged ≥70 years, 228 participated in a prospective cohort study. Exclusion criteria were: diagnosis of dementia; previous investigation at a memory clinic; and inability to write or read. Patients first filled out two self-administered cognitive tests (Test Your Memory and Self-Administered Gerocognitive Examination). Secondly, a general practitioner, blinded to Test Your Memory and Self-Administered Gerocognitive Examination scores, performed a structured evaluation using the Mini-Mental State Examination. Subsequently, patients suspected of cognitive impairment (on either the cognitive tests or general practitioner evaluation) and a random sample of 30% of patients not suspected of cognitive impairment were evaluated at a memory clinic. Diagnostic accuracy and area under the curve were determined for the Test Your Memory, Self-Administered Gerocognitive Examination and general practitioner evaluation compared with a memory clinic evaluation to detect cognitive impairment (mild cognitive impairment or dementia).

RESULTS

A total of 44 participants were diagnosed with cognitive impairment. The Test Your Memory and Self-Administered Gerocognitive Examination questionnaires had negative predictive values of 81 and 85%, respectively. Positive predictive values were 39 and 40%, respectively. The general practitioner evaluation had a negative predictive value of 83% and positive predictive value of 64%. The area under the curve was ~0.70 for all tests.

CONCLUSIONS

Both the tests evaluated in the present study can easily be used in case-finding strategies for cognitive impairment in patients with Type 2 diabetes in primary care. The Self-Administered Gerocognitive Examination had the best diagnostic accuracy and therefore we would have a slight preference for this test. Applying the Self-Administered Gerocognitive Examination would considerably reduce the number of patients in whom the general practitioner needs to evaluate cognitive functioning to tailor diabetes treatment.

Cerebrospinal fluid volumetric MRI mapping as a simple measurement for evaluating brain atrophy

Objectives

To assess whether volumetric cerebrospinal fluid (CSF) MRI can be used as a surrogate for brain atrophy assessment and to evaluate how the T₂ of the CSF relates to brain atrophy.

Methods

Twenty-eight subjects [mean age 64 (sd 2) years] were included; T₁-weighted and CSF MRI were performed. The first echo data of the CSF MRI sequence was used to obtain intracranial volume, CSF partial volume was measured voxel-wise to obtain CSF volume (V_CSF) and the T₂ of CSF (T_2,CSF) was calculated. The correlation between V_CSF / T_2,CSF and brain atrophy scores [global cortical atrophy (GCA) and medial temporal lobe atrophy (MTA)] was evaluated.

Results

Relative total, peripheral subarachnoidal, and ventricular V_CSF increased significantly with increased scores on the GCA and MTA (R = 0.83, 0.78 and 0.78 and R = 0.72, 0.62 and 0.86). Total, peripheral subarachnoidal, and ventricular T₂ of the CSF increased significantly with higher scores on the GCA and MTA (R = 0.72, 0.70 and 0.49 and R = 0.60, 0.57 and 0.41).

Conclusion

A fast, fully automated CSF MRI volumetric sequence is an alternative for qualitative atrophy scales. The T₂ of the CSF is related to brain atrophy and could thus be a marker of neurodegenerative disease.

Key points

• A 1:11 min CSF MRI volumetric sequence can evaluate brain atrophy.

• CSF MRI provides accurate atrophy assessment without partial volume effects.

• CSF MRI data can be processed quickly without user interaction.

• The measured T₂of the CSF is related to brain atrophy.

Electronic supplementary material

The online version of this article (doi:10.1007/s00330-015-3932-8) contains supplementary material, which is available to authorized users.

Cognitive performance and the course of depressive symptoms over 7 years of follow-up: the SMART-MR study

BACKGROUND

Depressive symptoms and cognitive impairment often co-occur, but their interactive relationship is complex and the direction of causation is still a topic of research. We examined the influence of cognitive performance on the course of depressive symptoms during 7 years of follow-up in patients with vascular disease.

METHOD

Within the SMART-MR study, 736 patients (mean age 62 ± 10 years) had neuropsychological assessment on four cognitive domains at baseline [memory (MEM), working memory (WMEM), executive functioning (EXEC), and information processing speed (SPEED)]. Depressive symptoms were assessed with the Patient Health Questionnaire-9 (PHQ-9) at baseline and every 6 months during 7 years of follow-up. Generalized Estimating Equation (GEE) models were used to assess the association between cognitive performance with depressive symptoms at multiple time points during follow-up. Interaction terms between the respective cognitive domains and time was included to examine if the course of depressive symptoms differed according to baseline cognitive performance.

RESULTS

The GEE analyses showed no significant interactions between the respective cognitive domains and time indicating no different course of depressive symptoms according to baseline cognitive performance. Lower MEM, EXEC or SPEED, but not WMEM performance, was significantly associated with more depressive symptoms during follow-up per z score decrease: MEM [B = 0.70, 95% confidence interval (CI) 0.35-1.05]; EXEC (B = 0.88, 95% CI 0.41-1.36), and SPEED (B = 0.57, 95% CI 0.21-0.92).

CONCLUSIONS

Poorer cognitive performance on the domains MEM, EXEC and SPEED, but not WMEM, was associated with higher levels of depressive symptoms over 7 years of follow-up, but not with a different course of depressive symptoms over time.

Phenotyping animal models of diabetic neuropathy: a consensus statement of the diabetic neuropathy study group of the EASD (Neurodiab)

NIDDK, JDRF, and the Diabetic Neuropathy Study Group of EASD sponsored a meeting to explore the current status of animal models of diabetic peripheral neuropathy. The goal of the workshop was to develop a set of consensus criteria for the phenotyping of rodent models of diabetic neuropathy. The discussion was divided into five areas: (1) status of commonly used rodent models of diabetes, (2) nerve structure, (3) electrophysiological assessments of nerve function, (4) behavioral assessments of nerve function, and (5) the role of biomarkers in disease phenotyping. Participants discussed the current understanding of each area, gold standards (if applicable) for assessments of function, improvements of existing techniques, and utility of known and exploratory biomarkers. The research opportunities in each area were outlined, providing a possible roadmap for future studies. The meeting concluded with a discussion on the merits and limitations of a unified approach to phenotyping rodent models of diabetic neuropathy and a consensus formed on the definition of the minimum criteria required for establishing the presence of the disease. A neuropathy phenotype in rodents was defined as the presence of statistically different values between diabetic and control animals in 2 of 3 assessments (nocifensive behavior, nerve conduction velocities, or nerve structure). The participants propose that this framework would allow different research groups to compare and share data, with an emphasis on data targeted toward the therapeutic efficacy of drug interventions.

Major depressive episodes over the course of 7 years and hippocampal subfield volumes at 7 tesla MRI: the PREDICT-MR study

INTRODUCTION

Smaller hippocampal volumes have been associated with major depressive disorder (MDD). The hippocampus consists of several subfields that may be differentially related to MDD. We investigated the association of occurrence of major depressive episodes (MDEs), assessed five times over seven years, with hippocampal subfield and entorhinal cortex volumes at 7 tesla MRI.

METHODS

In this prospective study of randomly selected general practice attendees, MDEs according to DSM-IV-R criteria were assessed at baseline and after 6, 12, 39 and 84 months follow-up. At the last follow-up, a T2 (0.7 mm(3)) 7 tesla MRI scan was obtained in 47 participants (60±10 years). The subiculum, cornu ammonis (CA) 1 to 3, dentate gyrus&CA4 and entorhinal cortex volumes were manually segmented according a published protocol.

RESULTS

Of the 47 participants, 13 had one MDE and 5 had multiple MDEs. ANCOVAs, adjusted for age, sex, education and intracranial volume, revealed no significant differences in hippocampal subfield or entorhinal cortex volumes between participants with and without an MDE in the preceding 84 months. Multiple episodes were associated with smaller subiculum volumes (B=-0.03 mL/episode; 95% CI -0.06; -0.003), but not with the other hippocampal subfield volumes, entorhinal cortex, or total hippocampal volume.

LIMITATIONS

A limitation of this study is the small sample size which makes replication necessary.

CONCLUSIONS

In this exploratory study, we found that an increasing number of major depressive episodes was associated with smaller subiculum volumes in middle-aged and older persons, but not with smaller volumes in other hippocampal subfields or the entorhinal cortex.

Methodological considerations on tract-based spatial statistics (TBSS)

Having gained a tremendous amount of popularity since its introduction in 2006, tract-based spatial statistics (TBSS) can now be considered as the standard approach for voxel-based analysis (VBA) of diffusion tensor imaging (DTI) data. Aiming to improve the sensitivity, objectivity, and interpretability of multi-subject DTI studies, TBSS includes a skeletonization step that alleviates residual image misalignment and obviates the need for data smoothing. Although TBSS represents an elegant and user-friendly framework that tackles numerous concerns existing in conventional VBA methods, it has limitations of its own, some of which have already been detailed in recent literature. In this work, we present general methodological considerations on TBSS and report on pitfalls that have not been described previously. In particular, we have identified specific assumptions of TBSS that may not be satisfied under typical conditions. Moreover, we demonstrate that the existence of such violations can severely affect the reliability of TBSS results. With TBSS being used increasingly, it is of paramount importance to acquaint TBSS users with these concerns, such that a well-informed decision can be made as to whether and how to pursue a TBSS analysis. Finally, in addition to raising awareness by providing our new insights, we provide constructive suggestions that could improve the validity and increase the impact of TBSS drastically.

Markers of low-grade inflammation and endothelial dysfunction are related to reduced information processing speed and executive functioning in an older population - the Hoorn Study

Low-grade inflammation and endothelial dysfunction are related to cognitive decline and dementia, in a complex interplay with vascular factors and aging. We investigated, in an older population, low-grade inflammation and endothelial dysfunction in relation to detailed assessment of cognitive functioning. Furthermore, we explored this association within the context of vascular factors. 377 participants (73 ± 6 years) of the population-based Hoorn Study were included. In plasma samples of 2000-2001 (n=363) and/or 2005-2008 (n=323), biomarkers were determined of low-grade inflammation (CRP, TNF-alpha, IL-6, IL-8, SAA, MPO, and sICAM-1) and endothelial dysfunction (vWF, sICAM-1, sVCAM-1, sTM, sE-selectin). In 2005-2008, all participants underwent neuropsychological examination. Composite z-scores were computed for low-grade inflammation and endothelial dysfunction at both time points, and for six domains of cognitive functioning (abstract reasoning, memory, information processing speed, attention and executive functioning, visuoconstruction, and language). The association between low-grade inflammation and endothelial dysfunction, and cognitive functioning was evaluated with linear regression analysis. In secondary analyses, we explored the relation with vascular risk factors and cardiovascular disease. Low-grade inflammation and endothelial dysfunction were associated with worse performance on information processing speed and attention and executive functioning, in prospective and cross-sectional analyses (standardized betas ranging from -0.20 to -0.10). No significant relation with other cognitive domains was observed. Adjusting for vascular factors slightly attenuated the associations. Low-grade inflammation and endothelial dysfunction accounted for only 2.6% explained variance in cognitive functioning, on top of related vascular risk factors and cardiovascular disease. Bootstrapping analyses show that low-grade inflammation and endothelial dysfunction mediate the relation between vascular risk factors and cognitive functioning. This study shows that low-grade inflammation and endothelial dysfunction contribute to reduced information processing speed and executive functioning in an older population.

Predictive value of thrombus attenuation on thin-slice non-contrast CT for persistent occlusion after intravenous thrombolysis

BACKGROUND

In stroke erythrocyte-rich thrombi are more sensitive to intravenous thrombolysis with recombinant tissue plasminogen activator (IV-rtPA) and have higher density on non-contrast CT (NCCT). We investigated the relationship between thrombus density and recanalization and whether persistent occlusions can be predicted by Hounsfield unit (HU) measurements.

METHODS

In 88 IV-rtPA-treated patients with intracranial ICA or MCA occluding thrombus and follow-up imaging, thrombus and contralateral vessel attenuation measurements were performed on thin-slice NCCT. Mean absolute and relative HU were compared between patients with persistent occlusion (modified Thrombolysis in Cerebral Infarction system, grade 0/1/2a) and recanalization (grade 2b/3). Univariate and multivariate (adjusted for stroke subtype, clot burden score, occlusion site and time to thrombolysis) odds ratios for persistent occlusion were calculated. Additional prognostic value for persistent occlusion was estimated by adding HU measurements to the area under the curve (AUC) of known determinants and calculating optimal cut-off values.

RESULTS

Patients with persistent occlusion (n = 19) had significant lower mean HU (absolute 52.2 ± 9.5, relative 1.29 ± 0.20) compared to recanalization (absolute 63.1 ± 10.7, relative 1.54 ± 0.23, both p < 0.0001). Odds ratios for persistent occlusion were 3.1 (95% confidence interval, CI 1.6-6.0) univariate and 3.1 (95% CI 1.7-5.7) multivariate per 10 absolute HU decrease and 3.2 (95% CI 1.6-6.5) univariate and 4.1 (95% CI 1.8-9.1) multivariate per 0.20 relative HU decrease. Attenuation measurements significantly increased the AUC (0.67) of the known determinants to 0.84 (absolute HU) and 0.86 (relative HU). Cut-off values of <56.5 absolute HU and <1.38 relative HU showed optimal predictive values for persistent occlusion.

CONCLUSIONS

Thrombus density is related to recanalization rate. Lower absolute and relative HU are independently related to persistent occlusion and HU measurements significantly increase discriminative performances of known recanalization determinants.

Neuroimaging standards for research into small vessel disease and its contribution to ageing and neurodegeneration

Cerebral small vessel disease (SVD) is a common accompaniment of ageing. Features seen on neuroimaging include recent small subcortical infarcts, lacunes, white matter hyperintensities, perivascular spaces, microbleeds, and brain atrophy. SVD can present as a stroke or cognitive decline, or can have few or no symptoms. SVD frequently coexists with neurodegenerative disease, and can exacerbate cognitive deficits, physical disabilities, and other symptoms of neurodegeneration. Terminology and definitions for imaging the features of SVD vary widely, which is also true for protocols for image acquisition and image analysis. This lack of consistency hampers progress in identifying the contribution of SVD to the pathophysiology and clinical features of common neurodegenerative diseases. We are an international working group from the Centres of Excellence in Neurodegeneration. We completed a structured process to develop definitions and imaging standards for markers and consequences of SVD. We aimed to achieve the following: first, to provide a common advisory about terms and definitions for features visible on MRI; second, to suggest minimum standards for image acquisition and analysis; third, to agree on standards for scientific reporting of changes related to SVD on neuroimaging; and fourth, to review emerging imaging methods for detection and quantification of preclinical manifestations of SVD. Our findings and recommendations apply to research studies, and can be used in the clinical setting to standardise image interpretation, acquisition, and reporting. This Position Paper summarises the main outcomes of this international effort to provide the STandards for ReportIng Vascular changes on nEuroimaging (STRIVE).

Effect of exercise training on acute (crush lesion) and chronic (diabetes mellitus) peripheral neuropathy in the rat

The effect of moderate exercise training on acute and chronic neuropathy in two separate experiments was examined. Acute nerve dysfunction was induced by sciatic nerve crush lesion and chronic neuropathy by streptozotocin-induced diabetes mellitus (experimental diabetic neuropathy; EDN). Moderate exercise training was achieved by placing food and water, separately, at either end of a U-shaped tubular home cage (8 m). Recovery from the crush lesion and the development of EDN were monitored by evaluating the free walking pattern and nerve conduction velocity (NCV), respectively. In the acute neuropathy model, 24 days of exercise after the crush lesion resulted in an enhanced return of motor function in the early phase of recovery (P < 0.01) and an increased sensory NCV after 250 days in the late phase (P < 0.001). Diabetic rats benefited from this exercise training by showing fewer signs of EDN, as evidenced by a superior motor function (toespreading, calculated from the free walking pattern; P < 0.05) and an improvement in both motor and sensory NCV (both P < 0.05). We conclude that moderate exercise training is effective in enhancing recovery from acute peripheral neuropathy and in ameliorating the consequences of experimental chronic neuropathy in diabetic rats.

An update on type 2 diabetes, vascular dementia and Alzheimer's disease

The risk of dementia is increased in people with type 2 diabetes mellitus (T2DM). This review gives an update on the relation between T2DM and specific dementia subtypes - i.e. Alzheimer's disease and vascular dementia - and underlying pathologies. We will show that while epidemiological studies link T2DM to Alzheimer's disease as well as vascular dementia, neuropathological studies attribute the increased dementia risk in T2DM patients primarily to vascular lesions in the brain. Risk factors for dementia among patients with T2DM are also addressed. Currently, there is evidence that microvascular complications, atherosclerosis and severe hypoglycemic events increase dementia risk. However, for a more complete understanding of risk factors for dementia in T2DM a life time perspective is needed. This should identify which individuals are at increased risk, what are vulnerable periods in life, and what are windows of opportunity for treatment. Currently, there are no DM specific treatments for dementia, but we will review observations from clinical trials that tried to prevent cognitive decline through intensified glycemic control and address other clinical implications of the association between T2DM and dementia.

Albuminuria and cognitive functioning in an older population: the Hoorn study

BACKGROUND/AIMS

Markers of vascular disease elsewhere in the body may reflect vascular abnormalities in the brain relevant to age-related cognitive decline and dementia. We examined the association between albuminuria, as a marker of microvascular damage, and cognition in older individuals.

METHODS

380 individuals (age 73 ± 6 years), participating in the population-based Hoorn Study, underwent extensive neuropsychological examination in 2005-2008, and urinary albumin-to-creatinine ratios measurements in 2000-2001 (n = 378) and/or 2005-2008 (n = 346). Cognition was expressed in z-scores on 6 domains.

RESULTS

In 2000-2001, 42 participants were with and 336 without albuminuria, and in 2005-2008 51 were with and 295 were without. In age-, sex- and premorbid IQ-adjusted analyses, participants with albuminuria 5-7 years earlier had slightly lower z-scores for the domains attention and executive functioning [mean difference: -0.21 (95% CI -0.40 to -0.02)] and language [-0.36 (95% CI -0.63 to -0.09)]. No statistically significant differences in cognition were found between participants with and without albuminuria at the time of neuropsychological testing.

CONCLUSION

Albuminuria predicts future modest cognitive decrements, but concurrent albuminuria is unrelated to cognitive functioning. The link between albuminuria and cognitive dysfunction may convey an etiological message, but because effect sizes were modest its value in prognostic models for cognitive decline may be limited.

Visual cerebral microbleed detection on 7T MR imaging: reliability and effects of image processing

SUMMARY

MR imaging at 7T has a high sensitivity for cerebral microbleed detection. We identified mIP processing conditions with an optimal balance between the number of visually detected microbleeds and the number of sections on 7T MR imaging. Even with optimal mIP processing, the limited size of some of the microbleeds and the susceptibility effects of other adjacent structures were a challenge for visual detection, which led to a modest inter-rater agreement, mainly due to missed microbleeds. Automated lesion-detection techniques may be required to optimally benefit from the increased spatial resolution offered by 7T MR imaging.

Dementia risk score predicts cognitive impairment after a period of 15 years in a nondemented population

BACKGROUND/AIM

Cardiovascular risk factors play an important role in the development of cognitive impairment and dementia. We examined whether a previously designed dementia risk score based on midlife vascular risk profiles also predicts cognitive impairment 15 years later.

METHODS

322 individuals without dementia from the population-based Hoorn study (aged 50-64 years) underwent a medical examination at baseline and a detailed cognitive assessment 15 years later. The relation between the risk score and late-life cognitive impairment in each of 6 domains was analyzed with logistic regression analysis.

RESULTS

The risk score was significantly related to impairment on the domains information-processing speed (p = 0.04), visuoconstruction (p = 0.04) and abstract reasoning (p = 0.02). Participants with a risk score of 9 points or more had a markedly increased risk of late-life impairment in the domains information-processing speed (OR 3.07, 95% CI 1.37-6.90; p = 0.007) and abstract reasoning (OR 3.97, 95% CI 1.07-14.71; p = 0.04).

CONCLUSION

A previously designed risk score for dementia also predicts late-life cognitive impairment. Because such impairment can lead to complaints and functional consequences, also in individuals who do not progress to dementia, identification of individuals at risk is important and can help to target preventive strategies.

Beta-cell dysfunction and insulin resistance after subarachnoid haemorrhage

BACKGROUND

Hyperglycaemia is a common finding and an independent risk factor for increased morbidity and mortality in aneurysmal subarachnoid haemorrhage (SAH). Although in these patients hyperglycaemia is commonly ascribed to insulin resistance, there is little understanding of underlying mechanisms.

AIMS

To prospectively study temporal disturbances of glucose metabolism after aneurysmal SAH in patients without known abnormalities of glucose metabolism and to explore possible correlations with markers of stress.

METHODS

In consecutive aneurysmal SAH patients not subjected to insulin therapy, in-hospital and follow-up oral glucose tolerance tests (OGTTs) and assessments of insulin resistance, pancreatic β-cell function, free fatty acids (FFA) and cortisol were performed and compared with reference values.

RESULTS

We included 13 patients. In the first 2 weeks of admission, median fasting glucose and FFA levels were elevated while insulin levels were not. OGTTs were indicative of glucose intolerance in all patients at days 3 and 7, while on follow-up 1 patient had glucose intolerance and all patients had normal fasting glucose levels. Pancreatic β-cell function was impaired throughout the first week and insulin resistance from day 4 to 10. Levels of cortisol correlated with higher fasting glucose and increased FFA. FFA in turn correlated with pancreatic β-cell dysfunction.

CONCLUSIONS

Aneurysmal SAH patients have transient abnormalities of glucose metabolism. During the first week, it appears to result predominantly from transient pancreatic β-cell dysfunction, in combination with insulin resistance.

A 4 year follow-up study of cognitive functioning in patients with type 2 diabetes mellitus

AIMS/HYPOTHESIS

Type 2 diabetes mellitus is associated with moderate decrements in cognitive functioning, mainly in verbal memory, information-processing speed and executive functions. How this cognitive profile evolves over time is uncertain. The present study aims to provide detailed information on the evolution of cognitive decrements in type 2 diabetes over time.

METHODS

Sixty-eight patients with type 2 diabetes and 38 controls matched for age, sex and estimated IQ performed an elaborate neuropsychological examination in 2002-2004 and again in 2006-2008, including 11 tasks covering five cognitive domains. Vascular and metabolic determinants were recorded. Data were analysed with repeated measures analysis of variance, including main effects for group, time and the group x time interaction.

RESULTS

Patients with type 2 diabetes showed moderate decrements in information-processing speed (mean difference in z scores [95% CI] -0.37 [-0.69, -0.05]) and attention and executive functions (-0.25 [-0.49, -0.01]) compared with controls at both the baseline and the 4 year follow-up examination. After 4 years both groups showed a decline in abstract reasoning (-0.16 [-0.30, -0.02]) and attention and executive functioning (-0.29 [-0.40, -0.17]), but there was no evidence for accelerated cognitive decline in the patients with type 2 diabetes as compared with controls (all p > 0.05).

CONCLUSIONS/INTERPRETATION

In non-demented patients with type 2 diabetes, cognitive decrements are moderate in size and cognitive decline over 4 years is largely within the range of what can be viewed in normal ageing. Apparently, diabetes-related cognitive changes develop slowly over a prolonged period of time.

Acute myocardial infarction complicating subarachnoid haemorrhage

An acute myocardial infarction is a rare complication of a subarachnoid haemorrhage. The combination of these two conditions imposes important treatment dilemmas. We describe two patients with this combination of life-threatening conditions. Patient 1 was treated with emergency percutaneous coronary intervention followed by clipping of the anterior communicating artery aneurysm. Six months after discharge the patient's memory and orientation had almost completely recovered. Patient 2 was treated with aspirin until coiling of the aneurysm could be performed. After successful coiling low-molecular-weight heparin was added. One week later the patient died due to a free wall rupture. (Neth Heart J 2009;17:284-7.).

Efficacy and safety of two 5 day insulin dosing regimens to achieve strict glycaemic control in patients with acute ischaemic stroke

BACKGROUND

In patients with acute ischaemic stroke and hyperglycaemia, prolonged strict glycaemic control may improve clinical outcome. The question is how to achieve this prolonged strict glycaemic control. In this study, the efficacy and safety of two regimens with different basal to meal related insulin ratio are described.

METHODS

33 patients with ischaemic stroke and hyperglycaemia at admission were randomised in an open design to receive: (1) conventional glucose lowering therapy, (2) strict glucose control with predominantly basal insulin using intravenous insulin or (3) strict glucose control with predominantly meal related insulin using subcutaneous insulin in the first 5 days after stroke. The target range of glucose control for the last two groups was 4.4-6.1 mmol/l. 16 consecutive patients without hyperglycaemia at admission were included to serve as normoglycaemic controls.

RESULTS

The median area under the curve (AUC) in the meal related insulin group was 386 mmol/l x 58 h (range 286-662) for days 2-5, and did not differ from the hyperglycaemic control group (median AUC 444 mmol/l x 58 h; range 388-620). There was also no difference in median AUC of the basal insulin group (453 mmol/l x 58 h, range 347-629) and the hyperglycaemic control group on days 2-5. In the first 12 hours, glucose profiles were lower in the groups treated with strict glucose control; median AUC was 90 mmol/l x 12 h (range 77-189) for the hyperglycaemic control group versus 81 mmol/l x 12 h (range 60-118) for the meal related insulin group (p = 0.03) and 74 mmol/l x 12 h (range 52-97) for the basal insulin group (p = 0.008).

CONCLUSION

In intermittently fed ischaemic stroke patients, strict glycaemic control between day 2 and day 5 with two different basal bolus regimens did not result in lower glucose profiles due to postprandial hyperglycaemia. Continuous enteral feeding may therefore be needed to achieve prolonged strict glycaemic control in acute stroke patients.

High mean fasting glucose levels independently predict poor outcome and delayed cerebral ischaemia after aneurysmal subarachnoid haemorrhage

BACKGROUND

Hyperglycaemia has been related to poor outcome and delayed cerebral ischaemia (DCI) after aneurysmal subarachnoid haemorrhage (aSAH).

OBJECTIVE

This study aimed to assess whether in patients with aSAH, levels of mean fasting glucose within the first week predict poor outcome and DCI better than single admission glucose levels alone.

METHODS

Data on non-diabetic patients admitted within 48 h after aSAH with at least two fasting glucose assessments in the first week were retrieved from a prospective database (n = 265). The association of admission glucose or mean fasting glucose, dichotomised at the median levels, with outcome was assessed using logistic regression, and for DCI using Cox regression. To explore whether the association between glucose levels and outcome was mediated by DCI, we adjusted for DCI.

RESULTS

The crude and multivariable adjusted odds ratios and 95% confidence intervals for poor outcome were 1.9 (1.1 to 3.2) and 1.6 (0.9 to 2.7) for high admission glucose and 3.5 (2.0 to 6.1) and 2.5 (1.4 to 4.6) for high mean fasting glucose. The crude and adjusted hazard ratios for DCI were 1.7 (1.1 to 2.5) and 1.4 (0.9 to 2.1) for high admission glucose and 2.0 (1.3 to 3.0) and 1.7 (1.1 to 2.7) for high mean fasting glucose. After adjusting for DCI, the odds ratios on poor outcome for high mean fasting glucose decreased only marginally.

CONCLUSIONS

Compared with high admission glucose, high mean fasting glucose, representing impaired glucose metabolism, is a better and independent predictor of poor outcome and DCI. DCI is not the key determinant in the relationship between high fasting glucose and poor outcome.

Cerebral perfusion in relation to cognitive function and type 2 diabetes

AIM/HYPOTHESIS

Underlying mechanisms for decreased cognitive functioning in patients with type 2 diabetes are unclear. In the general population, cerebral hypoperfusion is a risk factor for cognitive dysfunction and dementia. Reduced cerebral perfusion may account for cognitive impairments in diabetic patients relative to controls.

METHODS

A total of 98 patients with type 2 diabetes and 47 control participants underwent neuropsychological evaluation. Total cerebral blood flow (CBF) was assessed non-invasively by measuring the volume flow in the internal carotid arteries and basilar artery with two-dimensional phase-contrast magnetic resonance angiography. Relative total CBF, a measure of mean total cerebral perfusion, was obtained by expressing total CBF per 100 ml brain parenchyma volume.

RESULTS

Patients with type 2 diabetes performed worse on neuropsychological tests (p < 0.05). Total CBF per 100 ml brain parenchyma volume did not differ between participants with and without diabetes (difference -2.3 ml min(-1) 100 ml(-1); 95% CI -6.0, 1.3). In the entire group, total CBF per 100 ml brain parenchyma volume was positively associated with cognitive functioning (0.09 SD increase in composite z score per 10 ml min(-1) 100 ml(-1) increase in relative total CBF). This association was not affected by type 2 diabetes.

CONCLUSIONS/INTERPRETATION

Although total CBF per 100 ml brain parenchyma volume was associated with cognitive functioning, it did not explain cognitive impairments in patients with type 2 diabetes relative to controls.

Peripheral and central neurologic complications in type 2 diabetes mellitus: No association in individual patients

Diabetes mellitus is associated with end-organ complications in the peripheral and central nervous system. It is unknown if these complications share a common aetiology, and if they co-occur in the same patient. The aim of the present study was to relate different measures of peripheral neuropathy in patients with type 2 diabetes mellitus (DM2) to cognition and brain MRI. A standardized neurological examination and questionnaire, neuropsychological examination and brain MRI were performed in 122 patients with DM2 and 56 matched controls. Measures of peripheral neuropathy were vibration threshold, a sensory examination sum score and the Toronto Clinical Neuropathy Scoring System. Neuropsychological test scores were expressed in standardized z-values across five predetermined cognitive domains. White matter lesions and cortical and subcortical atrophy were rated on MRI. Overall 38% of the patients with DM2 and 12% of the controls were classified as having any neuropathy (p<0.001). Patients with DM2 had a lower performance on the neuropsychological tests, more white matter lesions (p<0.01) and more atrophy (p<0.01) than controls. Within the DM2 group none of the measures of peripheral neuropathy was related to MRI abnormalities or cognitive dysfunction (linear regression analyses, adjusted for age, education, sex). We conclude that peripheral neuropathy in patients with DM2 is not related to cognitive dysfunction and brain abnormalities. This indicates that central and peripheral neurological complications of DM2 might have different etiologies.

Metabolic and vascular determinants of impaired cognitive performance and abnormalities on brain magnetic resonance imaging in patients with type 2 diabetes

AIMS/HYPOTHESIS

The determinants of cerebral complications of type 2 diabetes are unclear. The present study aimed to identify metabolic and vascular factors that are associated with impaired cognitive performance and abnormalities on brain MRI in patients with type 2 diabetes.

METHODS

The study included 122 patients and 56 controls. Neuropsychological test scores were divided into five cognitive domains and expressed as standardised z values. Brain MRI scans were rated for white matter lesions (WML), cortical and subcortical atrophy, and infarcts. Data on glucose metabolism, vascular risk factors and micro- and macrovascular disease were collected.

RESULTS

Patients with type 2 diabetes had more cortical (p < 0.001) and subcortical (p < 0.01) atrophy and deep WML (p = 0.02) than the control group and their cognitive performance was worse. In multivariate regression analyses within the type 2 diabetes group, hypertension (p < 0.05) and a history of vascular events (p < 0.01) were associated with worse cognitive performance, while statin use was associated (p < 0.05) with better performance. Retinopathy and brain infarcts on MRI were associated with more severe cortical atrophy (both p < 0.01) and statin use with less atrophy (p < 0.05). Insulin level and brain infarcts were associated with more severe WML and statin use with less severe WML (all p < 0.05).

CONCLUSIONS/INTERPRETATION

Type 2 diabetes is associated with modest impairments in cognition, as well as atrophy and vascular lesions on MRI. This 'diabetic encephalopathy' is a multifactorial condition, for which atherosclerotic (macroangiopathic) vascular disease is an important determinant. Chronic hyperglycaemia, hyperinsulinaemia and hypertension may play additional roles.

The metabolic syndrome is associated with decelerated cognitive decline in the oldest old

BACKGROUND

The metabolic syndrome is a cluster of risk factors including hypertension, obesity, dyslipidemia, and impaired glucose metabolism, associated with cardiovascular disease. The metabolic syndrome also appears to predispose to cognitive dysfunction and dementia. In this study the association between the metabolic syndrome and cognitive function was examined in a population of the oldest old.

METHODS

The Leiden 85-Plus Study is a population-based study of 599 persons from age 85 onward. Cognitive function was assessed annually from age 85 to 90 by means of four neuropsychological tests. The presence (n = 237) or absence (n = 325) of the metabolic syndrome was recorded at baseline. Cross-sectional and prospective associations between the metabolic syndrome and cognitive function were analyzed with linear mixed models, adjusted for sex and level of education.

RESULTS

At age 85 the metabolic syndrome was not associated with lower cognitive performance. The metabolic syndrome was associated with a decelerated cognitive decline from age 85 to 90 on the Mini-Mental State Examination (additional annual effect 0.18 [0.07], p = 0.01), the Stroop Test (-1.49 [0.59], p = 0.01), and the Letter Digit Coding Test (0.26 [0.09], p = 0.005). This effect was mainly attributable to glucose, body mass index, and, to a lesser extent, blood pressure.

CONCLUSION

The association between the metabolic syndrome and accelerated cognitive decline, which has been reported in persons up to age 75, is not evident in a population of the oldest old. The concept of the metabolic syndrome may be less valid in this age group.

Automated measurement of brain and white matter lesion volume in type 2 diabetes mellitus

AIMS/HYPOTHESIS

Type 2 diabetes mellitus has been associated with brain atrophy and cognitive decline, but the association with ischaemic white matter lesions is unclear. Previous neuroimaging studies have mainly used semiquantitative rating scales to measure atrophy and white matter lesions (WMLs). In this study we used an automated segmentation technique to investigate the association of type 2 diabetes, several diabetes-related risk factors and cognition with cerebral tissue and WML volumes.

SUBJECTS AND METHODS

Magnetic resonance images of 99 patients with type 2 diabetes and 46 control participants from a population-based sample were segmented using a k-nearest neighbour classifier trained on ten manually segmented data sets. White matter, grey matter, lateral ventricles, cerebrospinal fluid not including lateral ventricles, and WML volumes were assessed. Analyses were adjusted for age, sex, level of education and intracranial volume.

RESULTS

Type 2 diabetes was associated with a smaller volume of grey matter (-21.8 ml; 95% CI -34.2, -9.4) and with larger lateral ventricle volume (7.1 ml; 95% CI 2.3, 12.0) and with larger white matter lesion volume (56.5%; 95% CI 4.0, 135.8), whereas white matter volume was not affected. In separate analyses for men and women, the effects of diabetes were only significant in women.

CONCLUSIONS/INTERPRETATION

The combination of atrophy with larger WML volume indicates that type 2 diabetes is associated with mixed pathology in the brain. The observed sex differences were unexpected and need to be addressed in further studies.