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Biomedical subjects

J S Snowden

Publications and source records attributed to J S Snowden.

At least 19 recordsLinked to original sources
PubMed2000

Cognitive change in motor neurone disease/amyotrophic lateral sclerosis (MND/ALS).

A motor neuronopathy complicating frontotemporal dementia (FTD) has been recognised and designated FTD/motor neurone disease (MND). FTD is characterised by profound character change and altered social conduct, and executive deficits, reflecting focal degeneration of the frontal and temporal neocortex. The motor neuronopathy comprises bulbar palsy and limb amyotrophy. The major histological change is typically of microvacuolation of the cerebral cortex, with atrophy of the bulbar neurones and anterior horn cells of the spinal cord. Ubiquitinated inclusion bodies occur in large pyramidal cortical neurones and in surviving cranial nerve nuclei and anterior horn cells. Evidence is emerging that some patients with classical MND/amyotrophic lateral sclerosis (ALS), who are thought not to be demented, develop cognitive deficits in the realm of frontal executive functions. Moreover, frontal lobe abnormalities have been demonstrated by neuroimaging. The findings point to a link between FTD/MND and cMND/ALS and suggest that a proportion of patients with cMND/ALS go on to develop FTD. Patients with cMND/ALS may not be equally vulnerable. The hypothesis is that patients who present with bulbar palsy and amyotrophy, rather than corticospinal and corticobulbar features, may be most susceptible to the development of FTD.

Amyotrophic Lateral Sclerosis↗
PubMed2000

The electroencephalogram in dementia with Lewy bodies.

OBJECTIVES: Dementia with Lewy bodies (DLB) is the second commonest neurodegenerative cause of dementia. While there is consensus on the clinical diagnostic criteria for DLB, the use of EEG to increase the diagnostic sensitivity has not been substantiated. MATERIAL AND METHODS: We studied the resting EEG findings in 18 consecutive patients with DLB and compared them with a control group of 20 patients with "probable" Alzheimer's disease (AD). We aimed to evaluate the use of EEG in a representative sample of patients with DLB. RESULTS: All patients with DLB fulfilled accepted clinical criteria for DLB. The DLB group had a more severe dementia than the AD group, as measured by the Mini-Mental State Examination (MMSE) test (DLB mean MMSE 9.4 and AD mean MMSE 17.2) despite a similar duration of overall severity of illness. The EEG was slow in both groups, predominantly in the 4-7 Hz range. Although there was no statistically significant difference in the EEG findings between the DLB and AD groups, there was a correlation between the EEG score and MMSE score (Spearman Rank correlation rs = -0.61, P < 0.001). CONCLUSION: These findings suggest that although patients with DLB have a more aggressive course than AD, EEG abnormalities do not differ in the 2 groups. However, we believe the EEG provides important supporting diagnostic information in DLB.

Aged↗
PubMed1999

Neuropsychiatric aspects of frontotemporal dementias.

Frontotemporal dementia (FTD) is a clinically distinct disorder that is under-recognized. A primary focus of recent research has been to delineate neuropsychiatric features that best discriminate FTD from other dementias, and to identify test instruments that elicit differentiating characteristics most effectively. Additional studies have taken advantage of the clinical and anatomic selectivity that is the hallmark of FTD to explore the functions of different regions of the frontal and temporal lobes. Symptomatic treatments for FTD have shown some promise, raising the potential for improved management in the future.

Dementia↗
PubMed1999

Evaluation of the NINCDS-ADRDA criteria in the differentiation of Alzheimer's disease and frontotemporal dementia.

OBJECTIVES: The diagnosis of Alzheimer's disease (AD) is now reliant on the use of NINCDS-ADRDA criteria. Other diseases causing dementia are being increasingly recognised--for example, frontotemporal dementia (FTD). Historically, these disorders have not been clearly demarcated from AD. This study assesses the capability of the NINCDS-ADRDA criteria to accurately distinguish AD from FTD in a series of pathologically proved cases. METHODS: The case records of 56 patients (30 with AD, 26 with FTD) who had undergone neuropsychological evaluation, brain imaging, and ultimately postmortem, were assessed in terms of whether at initial diagnosis the NINCDS-ADRDA criteria were successful in diagnosing those patients who had AD and excluding those who did not. RESULTS: (1) The overall sensitivity of the NINCDS-ADRDA criteria in diagnosing "probable" AD from 56 patients with cortical dementia (AD and FTD) was 0.93. However, the specificity was only 0.23; most patients with FTD also fulfilled NINCDS-ADRDA criteria for AD. (2) Cognitive deficits in the realms of orientation and praxis significantly increased the odds of a patient having AD compared with FTD, whereas deficits in problem solving significantly decreased the odds. Neuropsychological impairments in the domains of attention, language, perception, and memory as defined in the NINCDS-ADRDA statement did not contribute to the clinical differentiation of AD and FTD. CONCLUSION: NINCDS-ADRDA criteria fail accurately to differentiate AD from FTD. Suggestions to improve the diagnostic specificity of the current criteria are made.

Aged↗
PubMed1999

Semantic dysfunction in frontotemporal lobar degeneration.

Semantic dementia, characterized by loss of word meaning and impaired face and object recognition, is one of the clinical manifestations of frontotemporal lobar degeneration and is associated with atrophy of the inferior and middle temporal gyri. Patients may present predominantly with problems in naming and understanding words, or in face and object recognition, the verbal or nonverbal predominance reflecting the accent of atrophy on the left or right temporal lobe. Behavioural changes may occur, although these have a more obsessional quality than is typically seen in frontotemporal dementia (FTD). However, overlap in clinical symptomatology of semantic dementia and FTD may occur with disease progression reinforcing the link between these clinical syndromes. Semantic dysfunction is poorly recognized and may be mistaken for the amnesia of Alzheimer's disease, yet may be important in explaining some of the behavioural characteristics seen in focal cerebral degeneration.

Dementia↗
PubMed1998

Awareness of involuntary movements in Huntington disease.

OBJECTIVE: To determine why patients with Huntington disease are apparently unaware of their involuntary movements. DESIGN: Correlative study using a subjective report questionnaire of physical symptoms and objective measures of neurologic and cognitive dysfunction. PATIENTS: Forty patients with Huntington disease attending a regional Huntington disease clinic. RESULTS: Patients were poor at reporting experiential symptoms of involuntary movements. There was no relationship between self-report of these symptoms and objective indices of motor dysfunction or severity of cognitive impairment. Patients could, however, report secondary consequences of their movement disorder, which correlated highly with nonchoreic indices of motor dysfunction. CONCLUSIONS: Patients with Huntington disease have impaired subjective experience of chorea. Denial of symptoms is likely to have a physiological basis and is not a secondary consequence of patients' cognitive impairment or a psychological defense against a debilitating disease.

Adaptation, Psychological↗
PubMed1998

A clinical role for 99mTc-HMPAO SPECT in the investigation of dementia?

OBJECTIVES: To provide the clinician with a guide to the clinical utility of 99mTc-HMPAO single photon emission computed tomography (SPECT) and to the interpretation of specific test results in the differential diagnosis of dementia. METHODS: Three hundred and sixty three patients with dementia were studied prospectively for a median three (range 1-6) years and classified into disease groups on the basis of established clinical criteria. The degree to which different patterns of cerebral blood flow (CBF) abnormality found on 99mTc-HMPAO SPECT imaging at the time of initial patient presentation modified clinical diagnoses was determined by calculating the likelihood ratios for pairwise disease group comparisons. The optimal clinical usage of 99mTc-HMPAO SPECT was determined by calculating the percentage of significant test results for each pairwise disease group comparison. RESULTS: Bilateral posterior CBF abnormality was found to significantly increase the odds of a patient having Alzheimer's disease as opposed to vascular dementia or frontotemporal dementia. Bilateral anterior CBF abnormality significantly increased the odds of a patient having frontotemporal dementia as opposed to Alzheimer's disease, vascular dementia, or Lewy body disease. "Patchy" CBF changes significantly increased the odds of a patient having vascular dementia as opposed to Alzheimer's disease. Unilateral anterior, unilateral anterior plus unilateral posterior, and generalised CBF abnormality failed to contribute to the differentiation of any of these forms of dementia. CONCLUSIONS: 99mTc-HMPAO SPECT was found to be most useful in distinguishing Alzheimer's disease from vascular dementia and fronto temporal dementia, and least useful in differentiating between Alzheimer's disease and Lewy body disease, and between vascular dementia, frontotemporal dementia, and progressive aphasia. It is suggested that CBF SPECT should be used selectively and as an adjunct to clinical evaluation and CT.

Aged↗
PubMed1998

Frontotemporal lobar degeneration: a consensus on clinical diagnostic criteria.

OBJECTIVE: To improve clinical recognition and provide research diagnostic criteria for three clinical syndromes associated with frontotemporal lobar degeneration. METHODS: Consensus criteria for the three prototypic syndromes-frontotemporal dementia, progressive nonfluent aphasia, and semantic dementia-were developed by members of an international workshop on frontotemporal lobar degeneration. These criteria build on earlier published clinical diagnostic guidelines for frontotemporal dementia produced by some of the workshop members. RESULTS: The consensus criteria specify core and supportive features for each of the three prototypic clinical syndromes and provide broad inclusion and exclusion criteria for the generic entity of frontotemporal lobar degeneration. The criteria are presented in lists, and operational definitions for features are provided in the text. CONCLUSIONS: The criteria ought to provide the foundation for research work into the neuropsychology, neuropathology, genetics, molecular biology, and epidemiology of these important clinical disorders that account for a substantial proportion of cases of primary degenerative dementia occurring before the age of 65 years.

Dementia↗
PubMed1997

A 99mTc-HMPAO single-photon emission computed tomography study of Lewy body disease.

The purpose of this study was to investigate patterns of 99mTc-HMPAO single-photon emission computed tomography (SPECT) abnormality in Lewy body disease (LBD) and to compare findings with those encountered in Alzheimer's disease (AD). The study group comprised 20 consecutive patient referrals fulfilling clinical criteria for LBD. All patients had fluctuating cognitive impairment and 'subcortical' dysfunction with or without perceptuospatial and/or linguistic impairment. Six patients had asymmetrical signs of parkinsonism (three left-sided and three right-sided), and 14 patients had symmetrical features of extrapyramidal involvement. 99mTc-HMPAO SPECT imaging was performed on LBD patients and findings compared with those of 57 patients with 'probable' AD and 11 normal age-matched controls. Within the LBD and AD groups, patterns of cortical and subcortical blood-flow abnormality were compared with patterns of cognitive and neurological breakdown. LBD was associated with bilateral posterior cortical blood flow abnormality, a pattern strikingly similar to that found in AD. Within the LBD group, cortical blood-flow abnormality was found to reflect patterns of neurological dysfunction (parkinsonism) indicative of subcortical involvement. In contrast, cortical blood-flow changes did not reflect patterns of neuropsychological impairment suggestive of cortical dysfunction. Within the AD group, cortical blood-flow changes were mirrored by the pattern of neuropsychological impairment. Findings support the notion that cortical blood-flow abnormality in LBD might reflect a combination of direct cortical pathology and cortical deafferentation secondary to subcortical Lewy body pathology. It would appear that 99mTc-HMPAO SPECT imaging is of limited value in the clinical differentiation of LBD and AD.

Aged↗
PubMed1996

Atypical amyloid (A beta) deposition in the cerebellum in Alzheimer's disease: an immunohistochemical study using end-specific A beta monoclonal antibodies.

We have used the end-specific monoclonal antibodies to amyloid beta-protein (A beta), BC05 and BA27, to investigate the molecular characteristics of the cored or stellate type of amyloid plaque that is sometimes present, along with the more common diffuse type of plaque, in the cerebellar cortex in (usually younger) cases of Alzheimer's disease. In five such cases of Alzheimer's disease the (many) cored plaques were strongly BA27, but less strongly BC05, immunopositive, indicating the presence of (much) A beta 40 and A beta 42(43), respectively. Diffuse plaques were only BC05 positive, except on rare occasions where a litter BA27 reactivity was present. Cerebellar cored plaques, like the diffuse plaques, were not associated with tau or astrocytic (glial fibrillary acid protein) immunoreactivity, though in contrast to cerebellar diffuse plaques, but like the cored plaques in the cerebral cortex, microglial cells were usually present. The cause of this form of A beta deposition in the cerebellum is not known. Although congophilic angiopathy was severe in two patients, this was only mild in the other. Similar plaques were also seen in the cerebellum of most, but not all, of five other younger patients with chromosome 14-linked Alzheimer's disease and again, although congophilic angiopathy was severe in one such case with many cored plaques, this was not so in the others. At present the relationship (if any) between this pathological change and the possession of the chromosome 14 mutation of Alzheimer's disease or the occurrence of congophilic angiopathy remains uncertain.

Adult↗
PubMed1995

Apolipoprotein E allelic frequencies in patients with lobar atrophy.

Apolipoprotein E (ApoE) genotype was determined by polymerase chain reaction amplification and restriction digestion of DNA extracted from brain tissues of 26 patients with clinically diagnosed and pathologically verified lobar atrophy (LA) and from blood of a further 22 patients with clinical LA. Brain tissue from 50 patients with pathologically confirmed Alzheimer's disease (AD) was also examined. As has been previously reported, the ApoE E4 allele frequency was significantly increased in AD. However, no change in the frequency of ApoE alleles was found in two of the clinical and pathological forms of LA (dementia of frontal type and dementia of frontal type with motor neurone disease) although the ApoE E4 allele frequency was elevated in cases of non-fluent progressive aphasia in accordance with the presence of coincidental Alzheimer-type pathological changes.

Aged↗
PubMed1995

The topographic distribution of brain atrophy in cortical Lewy body disease: comparison with Alzheimer's disease.

The topographic distribution of brain atrophy was quantified by image analysis of fixed coronal brain slices from four patients dying with cortical Lewy body disease (CLBD) all with Alzheimer-type pathology and compared to that in four other patients of similar age and gender dying with Alzheimer's disease (AD) alone. The pattern of atrophy in CLBD (+AD) was broadly similar to that in AD alone, suggesting that tissue loss was due mostly to parallel Alzheimer-type pathological changes and that the presence of Lewy bodies in cortical and subcortical neurons contributed little, if anything, to the overall degree of atrophy.

Aged↗
PubMed1995

The contribution of single photon emission tomography to the clinical differentiation of degenerative cortical brain disorders.

The accurate clinical diagnosis of degenerative cortical brain disorders is a necessary prerequisite for patient management and the critical evaluation of new treatments. This study has evaluated the ability of single photon emission tomography (SPET) to differentiate between Alzheimer's disease (AD) and different forms of non-Alzheimer lobar atrophy (LA), using a multi-purpose system in widespread routine clinical use. 99mTc-HMPAO SPET was carried out in patients with AD and three clinical syndromes associated with LA: frontotemporal dementia (FTD), progressive non-fluent aphasia (PA) and semantic dementia (SD). Principal component (PC) analysis was performed on regional cerebral blood flow (rCBF) data and inter-group comparisons were performed for PC scores using multiple t-tests. Three PCs explained 86.5% of the variation in rCBF values between individual patients and normal controls. The first PC reflected the average rCBF value and separated patient groups from normal controls but failed to distinguish between patient groups. The second PC reflected anterior-posterior asymmetry and separated AD from all three forms of LA. This PC also separated FTD and SD from controls but failed to distinguish between FTD, PA and SD. The third PC reflected left-right asymmetry and separated PA from all other groups. 99mTc-HMPAO SPET is able to differentiate between degenerative cortical brain disorders in a simple and physiological meaningful way, thereby showing considerable potential as a routine tool in the clinical evaluation and differentiation of AD and LA.

Aged↗
PubMed1995

Inter-relation between "classic" motor neuron disease and frontotemporal dementia: neuropsychological and single photon emission computed tomography study.

The purpose of this study was to examine the possible association between "classic" motor neuron disease (cMND) and frontotemporal dementia (FTD), using neuropsychological evaluation and single photon emission computed tomography (SPECT). Psychological tests assessing language, perceptuospatial, memory, and "frontal lobe" functions were given to patients with cMND and test scores were compared with those of normal control subjects. 99mTc-HMPAO SPECT was performed on patients with cMND, FTD and motor neuron disease (FTD/MND), FTD alone, and normal control subjects. Regional cerebral blood flow indices (rCBFi) were determined in 36 cortical regions, and differences between grouped rCBFi data were investigated by canonical discriminant analysis. There were significant group differences in the scores of picture sequencing and token tests in patients with cMND compared with normal controls. Regional CBFi data showed frontal and anterior temporal reductions in patients with cMND compared with normal controls. A similar pattern of SPECT abnormality was seen in patients with FTD/MND and FTD alone, but to a more pronounced degree than in patients with cMND. Neuropsychological and SPECT findings in cMND, FTD/MND, and FTD showed a common pattern of cerebral involvement, most pronounced in the second two conditions. It is suggested that cMND, FTD/MND, and FTD represent a clinical range of a pathological continuum.

Adult↗
PubMed1995

Frontotemporal dementia and Alzheimer's disease: retrospective differentiation using information from informants.

The study examined the feasibility of differentiating frontotemporal dementia from Alzheimer's disease on the basis of retrospective historical information obtained from relatives of patients. A structured questionnaire was devised of patients' symptoms, with emphasis on those cognitive and neuropsychiatric features found in earlier prospective clinical studies to distinguish the two conditions. The questionnaire was given to close relatives of deceased patients in whom the diagnosis of non-Alzheimer's frontotemporal degeneration of Alzheimer's disease had been verified at necropsy. The interviewer had no previous contact or knowledge of those patients, nor clinical experience of patients with frontotemporal dementia. The questionnaire elicited a distinct profile of responses for the two diagnostic groups with emphasis on early personality change, unconcern, and socially inappropriate behaviour in frontotemporal dementia and disturbance in memory and topographical orientation prominent in patients with Alzheimer's disease. A scoring system separated out individual patients with frontotemporal dementia from those with Alzheimer's disease. It is concluded that it is possible to obtain useful information about the precise pattern of dementia from informants even many years after the patient's death. The questionnaire provides the foundation of a diagnostic instrument for use in family history studies of dementia.

Adult↗
PubMed1994

Choice of reference region in the quantification of single-photon emission tomography in primary degenerative dementia.

This study evaluated the effect of using two different reference regions in the quantification of single-photon emission tomography (SPET). SPET scans of 30 patients with Alzheimer's disease (AD) and 30 patients with frontotemporal dementia were compared with the scans of ten age-matched controls. Regions of interest (ROIs) were defined on transaxial slices by a semi-automatic method. Regional cerebral blood flow indices (rCBFi) in each ROI were determined by normalizing the count densities to both cerebellar and occipital cortex reference regions. Mean rCBFi for each ROI were calculated for the patient and control groups and significant group differences determined. The number and topographical distribution of ROIs with significant group differences varied depending upon the choice of reference region. The magnitude of these differences was greatest when the cerebellum was used as the reference region. The disparity between results obtained with the two reference regions was most apparent in the AD group. The reasons for these differences are discussed and we conclude that the cerebellum is the more appropriate choice of reference region in the quantification of SPET in primary degenerative dementia.

Alzheimer Disease↗
PubMed1993

The topographic distribution of brain atrophy in Huntington's disease and progressive supranuclear palsy.

The topographic distribution of brain atrophy was quantified by image analysis of fixed coronal brain slices from 12 patients dying with Huntington's disease (HD) and from 4 other patients dying with progressive supranuclear palsy (PSP). In HD, atrophy was maximal within the caudate nucleus, putamen and globus pallidus. However, the cerebral cortex was also atrophied with reductions in cross-sectional area within frontal, temporal and parietal lobes. In general, more white matter than grey matter was lost leading to an elevation in the grey/white matter ratio. The amygdala and thalamus were reduced in area. In PSP, lesser reductions in cortical area than those of HD were seen, these again being mostly due to a loss of white matter, resulting in an elevation of the grey/white ratio. The globus pallidus and thalamus were decreased in area, but no changes in the caudate nucleus and putamen were measured.

Adult↗