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Biomedical subjects

I McKeith

Publications and source records attributed to I McKeith.

At least 37 records · Page 2Linked to original sources
PubMed1999

Frequency of HLA-A and B alleles in early and late-onset Alzheimer's disease.

The frequency of various allele types of the class I Major Histocompatibility Complex (MHC) genes HLA-A and HLA-B were compared between pathologically confirmed groups of late and early-onset Alzheimer's disease (AD) and a control group. DNA was extracted from frozen brain tissue and the highly polymorphic second and third exons of the HLA-A and HLA-B genes were independently PCR amplified using specific primers. Individual allele types were identified using sequence-specific oligonucleotide probes. The results showed that the main frequency differences occurred between the late-onset AD and the control group however none of these reached statistical significance.

Adult↗
PubMed1999

Dementia with Lewy bodies.

OBJECTIVE: The aim of this paper is to summarise recent clinical and research findings with regard to dementia with Lewy bodies (DLB). METHOD: A literature review (Medline) was carried out, as well as a review of reports of recent DLB symposia of international meetings and of other relevant papers and data known to the authors. RESULTS: Dementia with Lewy bodies, as the disorder should be known, is the second commonest form of degenerative dementia, accounting for up to 20% cases in the elderly. It is characterised by fluctuating cognitive impairment, spontaneous parkinsonism and recurrent visual hallucinations. Consensus clinical and neuropathological criteria have been published. The clinical criteria have been shown to have high specificity, but may still lack sensitivity. Recognition of DLB is clinically important in view of the high incidence (60%) of adverse and life-threatening reaction to antipsychotics, the difference in prognosis and, possibly, the differential treatment response to cholinergic therapy. Neuroimaging changes have not been well described in DLB but some show promise as potential markers to differentiate DLB from AD. These include relative preservation of temporal lobe structures on magnetic resonance imaging and loss of pre- and postsynaptic dopaminergic markers on single photon emission tomography. CONCLUSIONS: Dementia with Lewy bodies is a common cause of cognitive impairment in late life which appears to be clinically and neuropathologically distinct from AD. All clinicians should be aware of the typical triad of clinical features (fluctuating cognitive impairment, visual hallucinations and parkinsonism) which characterise the disorder and either avoid antipsychotics or prescribe them with extreme caution in such patients. Further research is likely to result in advances in diagnostic methods and therapeutics in the near future.

Aged↗
PubMed1999

Neuronal nicotinic receptors in dementia with Lewy bodies and schizophrenia: alpha-bungarotoxin and nicotine binding in the thalamus.

Neuronal nicotinic receptors have been implicated in schizophrenia on the basis of the high incidence of tobacco smoking in patients, abnormalities in cytisine and alpha-bungarotoxin (alphaBGT) binding in the hippocampus, and linkage between auditory P50 deficits and the region of chromosome 15 coding the alpha7 subunit. In another disease associated with psychosis, dementia with Lewy bodies (DLB), in which visual hallucinations predominate, reductions in nicotine binding have been identified in various cortical and subcortical regions. We investigated both alphaBGT and nicotine binding autoradiographically in different thalamic nuclei in autopsy brain tissue from patients with schizophrenia and DLB. AlphaBGT binding in the reticular nucleus was moderately reduced (25%) in schizophrenia and more extensively reduced (50%) in DLB. There were no significant alterations in nicotine binding in schizophrenia, and in DLB, a trend towards moderate reductions in most nuclei reached significance in the lateral dorsal nucleus. It is concluded that widespread abnormalities of thalamic nicotine are not implicated in schizophrenia or DLB, but that reticular alphaBGT binding may be involved to a lesser and greater extent in the pathophysiology or psychopathology of both disorders.

Aged↗
PubMed1999

White matter lesions on magnetic resonance imaging in dementia with Lewy bodies, Alzheimer's disease, vascular dementia, and normal aging.

OBJECTIVES: Alzheimer's disease and vascular dementia are associated with an increase in changes in white matter on MRI. The aims were to investigate whether white matter changes also occur in dementia with Lewy bodies and to examine the relation between white matter lesions and the cognitive and non-cognitive features of dementia with Lewy bodies, Alzheimer's disease, and vascular dementia. METHODS: Proton density and T2 weighted images were obtained on a 1.0 Tesla MRI scanner in patients with dementia with Lewy bodies (consensus criteria; n=27, mean age=75.9 years), Alzheimer's disease (NINCDS/ADRDA; n=28, mean age=77.4 years), vascular dementia (NINDS/AIREN; n=25, mean age=76.8 years), and normal controls (n=26, mean age=76.2 years). Cognitive function, depressive symptoms, and psychotic features were assessed using a standardised protocol. Periventricular hyperintensities (PVHs), white matter hyperintensities (WMHs) and basal ganglia hyperintensities (BGHs) were visually rated blind to diagnosis using a semiquantitative scale. RESULTS: Periventricular hyperintensities were positively correlated with age and were more severe in all dementia groups than controls. Total deep hyperintensities scores (WMHs plus BGHs) were significantly higher in all dementia groups than controls and higher in patients with vascular dementia than those with dementia with Lewy bodies or Alzheimer's disease. In all patients with dementia, frontal WMHs were associated with higher depression scores and occipital WMHs were associated with an absence of visual hallucinations and delusions. CONCLUSION: In common with Alzheimer's disease and vascular dementia, PVHs and WMHs were significantly more extensive in dementia with Lewy bodies than in controls. This overlap between different dementias may reflect shared pathological mechanisms. The link between frontal WMHs and depression and the absence of occipital WMHs and psychotic symptoms has important implications for understanding the neurobiological basis of these symptoms.

Aged↗
PubMed1999

Association among visual hallucinations, visual acuity, and specific eye pathologies in Alzheimer's disease: treatment implications.

OBJECTIVE: Studies suggest a link between visual acuity and visual hallucinations in dementia, but links with specific eye pathologies have not been evaluated. METHOD: Fifty patients (20 with visual hallucinations, 30 without) with probable Alzheimer's disease had an evaluation of psychotic symptoms. Visual acuity was measured before and after refractions, and ophthalmological examinations included standardized assessments for cataracts and macular degeneration. RESULTS: Impaired visual acuity and the severity of cognitive impairments were significantly associated with visual hallucinations. No patients with normal acuity (6/5 or 6/6 on the Snellen chart) experienced these symptoms. Impaired acuity improved with refraction in 60% (N = 12) of the patients with visual hallucinations. Of specific eye pathologies, only cataracts were significantly associated with visual hallucinations. Descriptive follow-up information suggests that an optician's assessment for glasses improves outcome. CONCLUSIONS: Glasses and cataract surgery need evaluation as prophylactic or adjunctive treatments for visual hallucinations in patients with probable Alzheimer's disease.

Aged↗
PubMed1999

Psychiatric morbidity in dementia with Lewy bodies: a prospective clinical and neuropathological comparative study with Alzheimer's disease.

OBJECTIVE: The literature reports considerable variation in the rates of psychiatric morbidity for patients with dementia with Lewy bodies. The authors intended to clarify the frequency of psychiatric morbidity in dementia with Lewy bodies and how it differs from probable Alzheimer's disease. METHOD: The study incorporated two groups--a clinical case register cohort (98 with dementia with Lewy bodies; 92 with Alzheimer's disease) and 80 (40 with dementia with Lewy bodies: 40 with Alzheimer's disease) prospectively studied, neuropathologically confirmed cases. Diagnoses were made by using the McKeith et al. consensus criteria for dementia with Lewy bodies and the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association criteria for Alzheimer's disease. Neuropathological diagnoses were made by using the consensus criteria for dementia with Lewy bodies and the Mirra et al. protocol for Alzheimer's disease. RESULTS: The occurrence of psychiatric symptoms was reported over 1 month. Hallucinations, depression, delusions, and delusional misidentification were all significantly higher for patients with dementia with Lewy bodies. The differences in frequency between dementia with Lewy bodies and Alzheimer's disease for auditory and visual hallucinations were especially pronounced for patients with mild cognitive impairment. The presence of psychiatric symptoms at presentation was a better discriminator between dementia with Lewy bodies and Alzheimer's disease than occurrence over the course of dementia. CONCLUSIONS: Delusional misidentification and hallucinations in the early stages of dementia may improve differentiation between patients with dementia with Lewy bodies and those with Alzheimer's disease and have important treatment implications.

Aged↗
PubMed1999

A multicentre, randomized, double-blind, placebo-controlled study to evaluate the efficacy, tolerability and safety of two doses of metrifonate in patients with mild-to-moderate Alzheimer's disease: the MALT study.

BACKGROUND: Metrifonate is a long-lasting acetylcholinesterase inhibitor being developed for the symptomatic treatment of Alzheimer's disease (AD). OBJECTIVES: This study compared the efficacy, tolerability and safety of two doses of metrifonate in patients with mild-to-moderate AD, over a 26-week treatment period. METHODS: Six hundred and five patients were randomized to placebo (n=208), a 40/50 mg dose (40 or 50 mg by weight; n=200) or a 60/80 mg dose (60 or 80 mg by weight; n=197) metrifonate. Patients randomized to receive metrifonate were administered a once-daily loading dose of 80 or 120 mg based on weight for 2 weeks, followed by the relevant maintenance dose for 24 weeks. Four main clinical domains of AD were assessed: cognition (ADAS-cog and MMSE), psychiatric and behavioural symptoms (ADAS-noncog and NPI), instrumental and basic activities of daily living (DAD) and global functioning (CIBIC-plus, CIBIS-plus and GDS). RESULTS: ADAS-cog performance was significantly improved in the 60/80 mg and 40/50 mg dose groups, compared with placebo, in the intention-to-treat (ITT) population. In addition, statistically significant treatment differences were demonstrated between the 60/80 mg dose group and placebo on MMSE, ADAS-noncog, the NPI subitems of hallucinations and apathy, DAD, CIBIC-plus, CIBIS-plus and the GDS. The performance of the 40/50 mg dose group was also significantly superior to placebo on the CIBIS-plus and the NPI subitem aberrant motor behaviour. CONCLUSIONS: Metrifonate significantly improved a wide range of symptoms across all four clinical domains of AD in a dose-dependent manner, and was safe and well tolerated at both doses studied.

Activities of Daily Living↗
PubMed1998

Clinical neurochemistry: developments in dementia research based on brain bank material.

Brain tissue obtained at autopsy continues to provide unique opportunities in current dementia research. Not only is tissue analysis still essential for diagnosis, but investigation of neurochemical pathology, at a level of resolution beyond current in vivo imaging, continues to provide new insights into the involvement of neurotransmitter signalling systems. These are relevant to therapy which, with respect to symptoms such as cognitive impairment, psychosis and depression, is currently targeted to specific transmitter (cholinergic, dopaminergic and serotonergic) systems. This paper focuses on dopaminergic, cholinergic and histaminergic parameters in Alzheimer's disease (AD), Dementia with Lewy bodies (DLB) and Parkinson's disease (PD). In the normal striatum the dopamine transporter and D2 receptor exhibit distinct rostral-caudal distributions and D2 binding is affected by genetic polymorphism at the Taq 1A locus. The transporter is reduced in both DLB and PD but not AD, correlating with severity of extrapyramidal dysfunction, and receptor abnormalities are apparent in DLB patients responding adversely to neuroleptics. Striatal nicotine receptors are lost in all 3 disorders, further reduced as a result of neuroleptic medication, and elevated as a result of tobacco use. In the thalamus there are selective reductions in presynaptic cholinergic activity in DLB in the reticular nucleus which relate to symptoms of hallucinations and fluctuating consciousness prevalent in this disorder. In the hippocampus coupling of muscarinic M1 receptors, relevant to response to cholinergic therapy, is impaired in areas most affected by beta-amyloid plaques and intact in less affected areas. Analysis of histamine H2 receptors indicates that, despite presynaptic histamine abnormalities in AD, receptor numbers are normal. Such clinically and therapeutically relevant observations on human brain neurochemistry provide a basis for improving therapeutic strategies and prospects of diagnostic in vivo chemical imaging.

Brain↗
PubMed1998

High prevalence of neurovascular instability in neurodegenerative dementias.

Orthostatic hypotension and carotid sinus hypersensitivity were assessed in patients meeting clinical criteria for dementia with Lewy bodies (DLB; n=30) and AD (n=35). Cardioinhibitory carotid sinus hypersensitivity (CI) was the most common sign (AD patients, 28%; DLB patients, 41%). Preliminary data from a secondary analysis excluding patients with hypertension or EKG evidence of ischemia suggested that CI may be significantly more common in DLB. Larger studies are needed to evaluate the implications for treatment and to explore the underlying mechanisms.

Aged↗
PubMed1997

HLA-DR antigens associated with major genetic risk for late-onset Alzheimer's disease.

Hla-dr antigen types were determined from DNA isolated from post-mortem brain tissue of age-matched groups of 78 patients with pathologically confirmed late-onset Alzheimer's disease (AD) and 50 controls. The results suggest that for individuals with no apolipoprotein E epsilon 4 alleles the presence of either DR1, 2 or 3 antigens is associated with a significantly increased risk for development of late-onset AD. Conversely the DR4 or 6 antigens are associated with a decreased risk of similar magnitude. This DR effect, rather than prolonged use of non-steroidal anti-inflammatory drugs, could be responsible for the reported lower prevalence of AD in rheumatoid arthritis (a condition associated with an increased frequency of DR-4).

Age of Onset↗
PubMed1997

Lewy body dementia--clinical, pathological and neurochemical interconnections.

Senile dementia of Lewy body type or Lewy body dementia (SDLT or LBD) is defined as a Lewy body associated disease presenting in the elderly primarily with dementia with variable extrapyramidal disorder. Characteristic clinical symptoms include fluctuating cognitive impairment, psychotic features such as hallucinations and a particular sensitivity to neuroleptic medication. Although apolipoprotein e4 allele is increased 2-3 fold in SDLT (as in Alzheimer's disease) and beta-amyloidosis occurs in most cases, the most robust neurobiological correlate of the dementia so far identified appears to be extensive cholinergic deficits in the neocortex. This is consistent with previously reported correlations between cortical cholinergic activity and dementia in Parkinson's disease (PD) and Alzheimer's disease. There is also a significant interaction between the density of limbic cortical Lewy bodies and dementia in both SDLT and PD, although the cortical neuronal population affected remains to be identified. Cortical Lewy body density is positively correlated with the age of disease onset in PD and SDLT. This may account for the increased incidence of psychiatric syndromes, as opposed to extrapyramidal disorder in Lewy body disease with advancing age as may age-related loss of cholinergic activity in cortical areas such as the hippocampus.

Aged↗
PubMed1997

A detailed phenomenological comparison of complex visual hallucinations in dementia with Lewy bodies and Alzheimer's disease.

Visual hallucinations (VH) are a core feature of dementia with Lewy bodies (DLB), but little is known about their phenomenology. A total of 73 dementia patients (42 DLB, 30 Alzheimer's disease [AD], 1 undiagnosed) in contact with clinical services were assessed with a detailed standardized inventory. DLB was diagnosed according to the criteria of McKeith and colleagues, AD was diagnosed using the NINCDS-ADRDA criteria. Autopsy confirmation has been obtained when possible. VH were defined using the definition of Burns and colleagues. Detailed descriptions of hallucinatory experiences were recorded. Annual follow-up interviews were undertaken. The clinical diagnosis has been confirmed in 18 of the 19 cases that have come to autopsy. A total of 93% of DLB patients and 27% of AD patients experienced VH. DLB patients were significantly more likely to experience multiple VH that persisted over follow-up. They were significantly more likely to hear their VH speak but there were no significant differences in the other phenomenological characteristics including whether the hallucinations moved, the time of day that they were experienced, their size, the degree of insight, and whether they were complete. VH may be more likely to be multiple, to speak, and to be persistent in DLB patients. These characteristics could potentially aid accurate diagnosis.

Aged↗
PubMed1997

The UPDRS scale as a means of identifying extrapyramidal signs in patients suffering from dementia with Lewy bodies.

The study aimed to evaluate the merits of the Unified Parkinson's Disease Rating Scale (UPDRS) in the assessment of parkinsonism in patients suffering from Dementia with Lewy Bodies (DLB). Parkinsonian symptoms were assessed in 73 dementia patients using the UPDRS and staged using the Hoehn & Yahr system. A staging of 1 or greater was taken to indicate significant parkinsonism. DLB (n=42) was diagnosed using the McKeith et al. criteria, Alzheimer's disease (n=30) was diagnosed using the NINCDS ADRDA criteria. The inability of some patients to comply with some of the more complicated tasks meant that the full UPDRS assessment could only be completed in 35 (83%) of the DLB patients, 23 (66%) of whom had significant parkinsonism. Patients with parkinsonism were significantly younger than those without. A Principal Components Analysis derived a sub-scale including the items tremor at rest, action tremor, bradykinesia, facial expression and rigidity. These items had a specificity of 100% and a sensitivity of 85% for significant parkinsonism using a cut-off of 7/8. The brief scale had several advantages over the complete UPDRS. Unlike the full scale it was independent of the severity of cognitive impairment and the 5 key items could be assessed in 41 (98%) of the DLB patients. Autopsies have been completed on 31 patients, with a specificity of greater than 90% for the operationalized clinical diagnosis of DLB. It is suggested that a 5 item subscale of the UPDRS provides a reliable and generally applicable instrument for the assessment of parkinsonism in DLB patients.

Aged↗
PubMed1992

Neuroleptic sensitivity in patients with senile dementia of Lewy body type.

OBJECTIVE: To determine the outcome of administration of neuroleptics to patients with senile dementia of Lewy body type confirmed at necropsy. DESIGN: Retrospective analysis of clinical notes blind to neuropathological diagnosis. SETTING: Specialist psychogeriatric assessment units referring cases for necropsy to a teaching hospital neuropathology service. PATIENTS: 41 elderly patients with diagnosis of either Alzheimer type dementia (n = 21) or Lewy body type dementia (n = 20) confirmed at necropsy. MAIN OUTCOME MEASURES: Clinical state including extrapyramidal features before and after neuroleptic treatment and survival analysis of patients showing severe neuroleptic sensitivity compared with the remainder in the group. RESULTS: 16 (80%) patients with Lewy body type dementia received neuroleptics, 13 (81%) of whom reacted adversely; in seven (54%) the reactions were severe. Survival analysis showed an increased mortality in the year after presentation to psychiatric services compared with patients with mild or no neuroleptic sensitivity (hazard ratio 2.70 (95% confidence interval 2.50-8.99); (chi 2 = 2.68, p = 0.05). By contrast, only one (7%) of 14 patients with Alzheimer type dementia given neuroleptics showed severe neuroleptic sensitivity. CONCLUSIONS: Severe, and often fatal, neuroleptic sensitivity may occur in elderly patients with confusion, dementia, or behavioural disturbance. Its occurrence may indicate senile dementia of Lewy body type and this feature has been included in clinical diagnostic criteria for this type of dementia.

Aged↗
PubMed1991

Topography, extent, and clinical relevance of neurochemical deficits in dementia of Lewy body type, Parkinson's disease, and Alzheimer's disease.

Cholinergic and monoaminergic (dopaminergic and serotonergic) activities have been examined in postmortem brain tissue in senile dementia of Lewy body type, Parkinson's disease, and Alzheimer's disease. Quantitative data suggest that although extrapyramidal symptoms relate to striatal levels of dopamine, cognitive impairment is most closely associated with cholinergic (but not monoaminergic) deficits in temporal and archicortical areas. Hallucinations, which are most frequent in Lewy body dementia, appear to be related to an extensive cholinergic deficit in temporal neocortex and the resulting imbalance between decreased cholinergic and relatively preserved serotonergic activities. Topographic analyses such as these including consideration of quantitative "threshold" effects, may be relevant to the future anatomic focus of neurochemical investigations in dementia and to the development of appropriate experimental models.

Adult↗