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S E Black

Publications and source records attributed to S E Black.

At least 19 recordsLinked to original sources
PubMed2006

Anterior-medial thalamic lesions in dementia: frequent, and volume dependently associated with sudden cognitive decline.

BACKGROUND: The anterior-medial thalamus (AMT), which is associated with memory processing, is severely affected by Alzheimer's disease pathology and, when damaged, can be the sole cause of dementia. OBJECTIVE: To assess the frequency of magnetic resonance imaging (MRI) hyperintensities affecting the AMT, and their relationship with sudden cognitive decline. METHODS: 205 consecutive participants from a university cognitive neurology clinic underwent clinical evaluation, neuropsychological testing and quantitative MRI. RESULTS: AMT hyperintensities >5 mm3 occurred in 0 of 34 normal controls but were found in 5 of 30 (17%) participants with cognitive impairment with no dementia (CIND), 9 of 109 (8%) patients with probable Alzheimer's disease, 7 of 17 (41%) with mixed disease and 8 of 15 (53%) with probable vascular dementia (VaD). AMT hyperintensities occurred more often in participants with stepwise decline than in those with slow progression (chi2 = 31.7; p<0.001). Of the 29 people with AMT hyperintensities, those with slow progression had smaller medial temporal width (p<0.001) and smaller anterior-medial thalamic hyperintensities (p<0.001). In a logistic regression model, both variables were significant, and the pattern of decline was correctly classified in 86% of the sample (Cox and Snell R2 = 0.56; p<0.001). Those with AMT hyperintensities >55 mm3 were likely to have stepwise decline in cognitive function regardless of medial temporal lobe width; in contrast, those with smaller AMT hyperintensities showed a stepwise decline only in the absence of medial temporal lobe atrophy. All patients with VaD had left-sided AMT hyperintensities, whereas those with CIND had right-sided AMT hyperintensities. CONCLUSIONS: AMT hyperintensities >55 mm3 probably result in symptomatic decline, whereas smaller lesions may go unrecognised by clinicians and radiologists. Only half of those with AMT hyperintensities had diagnoses of VaD or mixed disease; the other AMT hyperintensities occurred in patients diagnosed with Alzheimer's disease or CIND. These silent hyperintensities may nevertheless contribute to cognitive dysfunction. AMT hyperintensities may represent a major and under-recognised contributor to cognitive impairment.

Adult↗
PubMed2006

Identification of penumbra and infarct in acute ischemic stroke using computed tomography perfusion-derived blood flow and blood volume measurements.

BACKGROUND AND PURPOSE: We investigated whether computed tomography (CT) perfusion-derived cerebral blood flow (CBF) and cerebral blood volume (CBV) could be used to differentiate between penumbra and infarcted gray matter in a limited, exploratory sample of acute stroke patients. METHODS: Thirty patients underwent a noncontrast CT (NCCT), CT angiography (CTA), and CT perfusion (CTP) scan within 7 hours of stroke onset, NCCT and CTA at 24 hours, and NCCT at 5 to 7 days. Twenty-five patients met the criteria for inclusion and were subsequently divided into 2 groups: those with recanalization at 24 hours (n=16) and those without (n=9). Penumbra was operationally defined as tissue with an admission CBF <25 mL x 100 g(-1) x min(-1) that was not infarcted on the 5- to 7-day NCCT. Logistic regression was applied to differentiate between infarct and penumbra data points. RESULTS: For recanalized patients, CBF was significantly lower (P<0.05) for infarct (13.3+/-3.75 mL x 100 g(-1) x min(-1)) than penumbra (25.0+/-3.82 mL x 100 g(-1) x min(-1)). CBV in the penumbra (2.15+/-0.43 mL x 100 g(-1)) was significantly higher than contralateral (1.78+/-0.30 mL x 100 g(-1)) and infarcted tissue (1.12+/-0.37 mL x 100 g(-1)). Logistic regression using an interaction term (CBFxCBV) resulted in sensitivity, specificity, and accuracy of 97.0%, 97.2%, and 97.1%, respectively. The interaction term resulted in a significantly better (P<0.05) fit than CBF or CBV alone, suggesting that the CBV threshold for infarction varies with CBF. For patients without recanalization, CBF and CBV for infarcted regions were 15.1+/-5.67 mL x 100 g(-1) x min(-1) and 1.17+/-0.41 mL x 100 g(-1), respectively. CONCLUSIONS: We have shown in a limited sample of patients that CBF and CBV obtained from CTP can be sensitive and specific for infarction and should be investigated further in a prospective trial to assess their utility for differentiating between infarct and penumbra.

Acute Disease↗
PubMed2006

Characterizing neuropsychiatric symptoms in subjects referred to dementia clinics.

OBJECTIVE: To characterize the neuropsychiatric symptoms (NPS) of subjects classified as not cognitively impaired (NCI), cognitively impaired-not demented (CIND), and dementia. METHODS: A Canadian Cohort Study of Cognitive Impairment and Related Dementias (ACCORD) is a longitudinal investigation of individuals referred to eight Canadian dementia centers for evaluation of cognitive impairment and neurobehavioral symptoms. Of the inception cohort of 804 subjects for whom the informant-based Neuropsychiatric Inventory (NPI) was completed at study entry, 35 were classified as NCI, 193 as CIND, and 576 as dementia. The three diagnostic groups were compared on each of the 12 NPI items. Within each diagnostic group, comparisons were also made between symptomatic (NPS+; total score > 1) and asymptomatic (NPS-; total score = 0) subjects on measures of general cognitive status and functional disability. A subset of the NCI and CIND individuals were also compared on a comprehensive neuropsychological test battery. RESULTS: There was at least one NPI item reported in 60% of subjects with NCI, 74% with CIND, and 89% with dementia. The item scores for delusions, hallucinations, agitation, apathy, disinhibition, aberrant motor behavior, and problems with appetite were greater in dementia subjects than in NCI or CIND. There were no significant differences between subjects with NCI and CIND on any NPI item. For each diagnostic group, NPS+ subjects were more impaired on functional but not neuropsychological measures. CONCLUSIONS: Across all levels of cognition, neuropsychiatric symptoms (NPS) are an important feature in individuals referred to dementia clinics. The current data suggest that NPS may precede cognitive deficits in individuals classified as not cognitively impaired and cognitively impaired-not demented.

Aged↗
PubMed2006

Cholinesterase inhibitors slow decline in executive functions, rather than memory, in Alzheimer's disease: a 1-year observational study in the Sunnybrook dementia cohort.

To determine if there are differential treatment effects of second-generation cholinesterase inhibitors over one year, 130 patients (untreated=65, treated=65) meeting NINCDS-ADRDA criteria for mild or moderate probable AD underwent standardized cognitive testing at baseline and 12 months later at a university memory clinic. Patients were followed either prior to or after the availability of treatment and were matched on education and baseline Mini Mental State Examination (MMSE). A detailed medical history evaluation was conducted. In this well matched longitudinal observational cohort study, there were no differences in the prevalence of comorbid illnesses, concomitant medication use or vascular risk factors except for a greater number of treated patients with a previous history of smoking. Separate repeated measures MANCOVAs on the MMSE, Mattis Dementia Rating Scale (DRS), and its 5 subscores (attention, initiation/perseveration, conceptualization, construction and memory) (Bonferroni corrected), after covarying for the effects of smoking, and SSRI use, showed less decline over one year in the treated group in overall cognition and in all subscores of the DRS except for memory (effect sizes 0.5-0.7). Less decline was also seen in the treated group in function and in instrumental and basic activities of daily living as measured with the Disability Assessment for Dementia Scale (DAD) (effect sizes 0.4-0.8). Executive, language and visuospatial functions, rather than memory, appeared to be more amenable to stabilization over one year by cholinesterase inhibitors in AD.

Aged↗
PubMed2005

The behavioural neurology assessment.

BACKGROUND: We present information regarding the standardization, reliability and clinical validity of two versions of the Behavioural Neurology Assessment (BNA). The BNA-Long Form consists of 24 subtests within separate domains: Attention, Memory, Language, Visuospatial Function, Executive Function, and Praxis. The BNA-Short Form consists of 13 subtests within the domains of Attention, Memory, Naming, Visuospatial Function and Executive Function. In addition to individual domain indices, a Grand Total score was calculated for both BNA versions. OBJECTIVE: To standardize the administration and scoring and validate the BNA for detection of dementia. METHODS: Standardized normative data were obtained on 115 healthy subjects ranging in age from 50 to 95. Test-retest stability was obtained on 19 subjects and clinical validity was investigated by administering the BNA and Mini-Mental Status Examination (MMSE) to 29 patients with dementia and 29 age-matched healthy subjects (controls). RESULTS: Age had a significant effect on all but the Visuospatial and Praxis indices of the BNA-Long Form and an effect on Naming and Grand Total score of the Short-Form. Internal consistency (Cronbach's coefficient alpha) was .87 and .67 for the Long and Short Forms (.95 and .96 for dementia and control groups combined). Test-retest stability was acceptable. Grand Total indices of both BNA versions showed significant, positive correlations with the MMSE. Both BNA versions had superior sensitivity to dementia relative to the MMSE (.93 versus .79). Specificity was equivalent to the MMSE (.93 versus .97). CONCLUSIONS: Positive predictive values of the BNA and MMSE are equivalent but the BNA provides superior negative predictive value.

Age Factors↗
PubMed2004

Diagnostic utility of abbreviated fluency measures in Alzheimer disease and vascular dementia.

BACKGROUND: Several studies indicate semantic fluency more sensitively discriminates patients with Alzheimer disease (AD) from normal elderly persons, with disproportionate impairment of semantic over phonemic fluency. OBJECTIVE: To determine the ability of abbreviated fluency measures in the clinic setting (1-minute letter F and animal fluency tests) to detect AD, and to assess whether difference scores between these measures discriminate patients with AD and vascular dementia (VaD) from normal elderly persons. METHODS: The authors studied patients with AD (n = 98) meeting National Institute of Neurological Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria, VaD patients (n = 18) meeting National Institute of Neurological Disorders and Stroke-Association Internationale pour la Recherche et l'Enseignement en Neurosciences criteria, cognitively impaired but not demented patients (CIND; n = 25), vascular CIND patients (VCIND; n = 24), and normal control subjects (NCs; n = 46). RESULTS: Analysis of covariance controlling for age, education, and overall impairment indicated all groups generated fewer animal names compared with NCs, whereas only VaD patients generated fewer letter F words compared with NCs. On standardized scores, patients with AD and CIND, unlike those with VCIND and VaD, scored significantly worse on the animal fluency test than on the letter F fluency test. The animal fluency test was superior in discriminating all patient groups from NCs. Positive likelihood ratios (PLRs) revealed animal fluency scores <15 were 20 times more likely in a patient with AD than in an NC (sensitivity = 0.88; specificity = 0.96). Letter F scores <4 discriminated VaD from AD patients (PLR = 4.0; sensitivity = 0.44; specificity = 0.90). Difference scores <0 (i.e., fewer animal than letter F words) discriminated patients with VCIND from those with CIND (PLR = 2.5; sensitivity = 0.32; specificity = 1.00). CONCLUSIONS: A 1-minute semantic fluency test can assist in early detection of dementia in the memory clinic setting.

Aged↗
PubMed2004

Semiautomatic brain region extraction: a method of parcellating brain regions from structural magnetic resonance images.

Structural MR imaging has become essential to the evaluation of regional brain changes in both healthy aging and disease-related processes. Several methods have been developed to measure structure size and regional brain volumes, but many of these methods involve substantial manual tracing and/or landmark identification. We present a new technique, semiautomatic brain region extraction (SABRE), for the rapid and reliable parcellation of cortical and subcortical brain regions. We combine the SABRE parcellation with tissue compartment segmentation [NeuroImage 17 (2002) 1087] to produce measures of gray matter (GM), white matter (WM), ventricular CSF, and sulcal CSF for 26 brain regions. Because SABRE restricts user input to a few easily identified landmarks, inter-rater reliability is high for all volumes, with all coefficients between 0.91 and 0.99. To assess construct validity, we contrasted SABRE-derived volumetric data from healthy young and older adults. Results from the SABRE parcellation and tissue segmentation showed significant differences in multiple brain regions in keeping with regional atrophy described in the literature by researchers using lengthy manual tracing methods. Our findings show that SABRE is a reliable semiautomatic method for assessing regional tissue volumes that provides significant timesavings over purely manual methods, yet maintains information about individual cortical landmarks.

Adult↗
PubMed2004

Linear width of the medial temporal lobe can discriminate Alzheimer's disease from normal aging: the Sunnybrook dementia study.

To discriminate Alzheimer's disease (AD) from healthy controls, the thinnest medial temporal lobe (tMTL) width on 3D-MRI was measured according to a newly developed method at the inter-collicular sulcus (ICS) level with scans aligned to the long axis of the hippocampus in 22 mild, 27 moderate probable AD patients and 41 healthy controls. For comparison, MTL width replicating the technique of Jobst et al. (jMTL) as well as hippocampal and parahippocampal volumes, were also measured. Using logistic regression taking into account age, sex, and education, tMTL width classified mild AD from controls with a sensitivity of 86%, specificity of 95% and accuracy of 92%. Similar values were obtained for moderate or total AD group versus controls. By comparison, jMTL width was only useful in distinguishing moderate AD from controls, and volumetric measures were equally sensitive in classifying mild and moderate AD in our sample. This quick, reliable, and standardized measurement of tMTL can be helpful in differentiating even mild AD from controls with reasonable accuracy.

Aged↗
PubMed2002

A robust method for extraction and automatic segmentation of brain images.

A new protocol is introduced for brain extraction and automatic tissue segmentation of MR images. For the brain extraction algorithm, proton density and T2-weighted images are used to generate a brain mask encompassing the full intracranial cavity. Segmentation of brain tissues into gray matter (GM), white matter (WM), and cerebral spinal fluid (CSF) is accomplished on a T1-weighted image after applying the brain mask. The fully automatic segmentation algorithm is histogram-based and uses the Expectation Maximization algorithm to model a four-Gaussian mixture for both global and local histograms. The means of the local Gaussians for GM, WM, and CSF are used to set local thresholds for tissue classification. Reproducibility of the extraction procedure was excellent, with average variation in intracranial capacity (TIC) of 0.13 and 0.66% TIC in 12 healthy normal and 33 Alzheimer brains, respectively. Repeatability of the segmentation algorithm, tested on healthy normal images, indicated scan-rescan differences in global tissue volumes of less than 0.30% TIC. Reproducibility at the regional level was established by comparing segmentation results within the 12 major Talairach subdivisions. Accuracy of the algorithm was tested on a digital brain phantom, and errors were less than 1% of the phantom volume. Maximal Type I and Type II classification errors were low, ranging between 2.2 and 4.3% of phantom volume. The algorithm was also insensitive to variation in parameter initialization values. The protocol is robust, fast, and its success in segmenting normal as well as diseased brains makes it an attractive clinical application.

Adult↗
PubMed2002

Oculographic analysis of word reading in hemispatial neglect.

Neglect dyslexia is a disorder in which individuals misread text appearing on the contralateral side of space following an acquired lesion, usually to the right parietal lobe. This disorder is generally attributed to an impairment in representing spatial information. To determine whether the spatial representations underlying reading differ from those mediating other forms of visual behavior, we investigated the co-occurrence of neglect dyslexia with that of neglect, which manifests on tasks such as line bisection or line cancellation. We also examined the correlation between neglect dyslexia, when present, and eye movements in order to characterize the neglect dyslexia disorder further. Whereas there is no clear relationship between the reading disorder and other symptoms of visuospatial neglect, suggesting segregated spatial representations, there is a direct correspondence between the oculomotor performance of patients with neglect dyslexia and their reading behavior. This latter result suggests that the reading deficit may well arise from the failure to register and perceive the contralesional information.

Adult↗
PubMed2002

Functional reorganisation of memory after traumatic brain injury: a study with H(2)(15)0 positron emission tomography.

OBJECTIVE: To study the effects of moderate to severe traumatic brain injury (TBI) on the functional neuroanatomy supporting memory retrieval. METHODS: Subjects were six patients who had sustained a moderate to severe TBI about four years before scanning and had since made a good recovery. Eleven healthy young adults matched to the patients for age and education served as controls. An established H(2)(15)0 positron emission tomography paradigm was used to elicit brain activations in response to memory retrieval. TBI patients' patterns of brain activation were compared statistically with those of control subjects. Both group and individual case data were analysed. RESULTS: Both TBI patients and controls engaged frontal, temporal, and parietal regions known to be involved in memory retrieval, yet the TBI patients showed relative increases in frontal, anterior cingulate, and occipital activity. The hemispheric asymmetry characteristic of controls was attenuated in patients with TBI. Reduced activation was noted in the right dorsomedial thalamus. Although local aspects of this pattern were affected by the presence of focal lesions and performance differences, the overall pattern was reliable across patients and comparable to functional neuroimaging results reported for normal aging, Alzheimer's disease, and other patients with TBI. CONCLUSIONS: The TBI patients performed memory tasks using altered functional neuroanatomical networks. These changes are probably the result of diffuse axonal injury and may reflect either cortical disinhibition attributable to disconnection or compensation for inefficient mnemonic processes.

Adult↗
PubMed2002

Cognitive impairment in dementia: correlations with atrophy and cerebrovascular disease quantified by magnetic resonance imaging.

This project assessed the contributions of atrophy and cerebrovascular disease (CVD) to cognitive impairment in dementia. Ten individuals with clinically diagnosed pure VaD were age-, sex-, and education-matched to individuals with AD. All participants underwent neuropsychological testing and MRI which were processed to generate quantitative indices of atrophy and CVD. A linear regression, including thalamic lesion and vCSF volumes, predicted cognitive status (R2 = .74; p < .0005). Three VaD subgroups were identified: thalamic lesion (n = 4), hippocampal infarcts (n = 3), and other (n = 3). In participants without thalamic lesion, vCSF predicted general cognition (R2 = .48), hippocampal atrophy predicted memory impairment (R2 = .33), and white matter lesions predicted executive dysfunction (R2 = .48). Both atrophy and CVD burden correlated highly with cognitive impairment and should be simultaneously assessed in studies of brain-behaviour relations in dementia.

Alzheimer Disease↗
PubMed2001

Beyond the hippocampus: MRI volumetry confirms widespread limbic atrophy in AD.

OBJECTIVE: To examine volumetric changes in limbic structures in patients with probable AD using planimetric measures on MRI. METHOD: Limbic structures (i.e., hippocampus, amygdala, anterior thalamus, hypothalamus, mamillary bodies, basal forebrain, septal area, fornix, and cingulate, orbitofrontal, and parahippocampal cortices) were traced on 3D T1-weighted MR images of 40 patients with mild to moderate AD and 40 age-, sex-, and education-matched normal control subjects. Limbic volumes were compared between groups and the predictive ability was assessed. RESULTS: Overall, limbic structures showed significant atrophy in AD patients compared with normal control subjects. Differences (p < 0.05) were found in all limbic regions except the anterior cingulate cortex. The greatest percentage volumetric losses occurred in the septal area (34%), hippocampus (28%), amygdala (21%), parahippocampal cortex (21%), and posterior cingulate cortex (20%). Combining volumetric measures of amygdala and septal area distinguished patients with AD from normal control subjects with 93% accuracy. CONCLUSIONS: These results verify that system-wide limbic degeneration occurs in patients with AD. In addition, atrophy in selected limbic structures was used to distinguish patients with AD from normal elderly individuals with over 90% accuracy in this select clinical sample. The measures require further exploration in samples more representative of those seen by primary care physicians before their utility can be accurately assessed.

Aged↗
PubMed2001

Update on intravenous tissue plasminogen activator for acute stroke: from clinical trials to clinical practice.

Tissue plasminogen activator (tPA) injected intravenously within 3 hours of symptom onset has emerged as a treatment option for acute ischemic stroke. Although controversial and not universally accepted, its use in carefully selected patients is supported by evidence from randomized controlled trials and by mounting community experience. In this paper we review the literature published in the past 5 years regarding the safety, clinical trial efficacy and real-world effectiveness of intravenous tPA for stroke. First we review data from the phase III clinical trials on which approval for tPA is based. Then we summarize a growing literature of postmarketing phase IV studies and discuss the limitations and challenges that lie ahead. Our aim is to provide clinicians with an overview of this evolving therapy.

Acute Disease↗
PubMed2001

Bilateral movement enhances ipsilesional cortical activity in acute stroke: a pilot functional MRI study.

Functional MRI was performed in two acute stroke patients and six control subjects performing unilateral and bilateral repetitive gripping tasks. Patients were tested at three time points during recovery. Initially, bilateral movement enhanced activation in the primary motor cortex (M1) of the affected hemisphere compared with unilateral paretic hand movement. With recovery, activation of M1 in the affected hemisphere did not differ between unilateral paretic hand and bilateral movement. These preliminary data may have potential implications for acute stroke motor rehabilitation.

Acute Disease↗