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G Blessed

Publications and source records attributed to G Blessed.

At least 19 recordsLinked to original sources
PubMed1996

Cross-national interrater reliability of dementia diagnosis in the elderly and factors associated with disagreement.

Thirteen researchers from five centers in Australia, Germany, the Netherlands, United Kingdom, and United States applied DSM-III-R and Clinical Dementia Rating (CDR) syndrome-level dementia criteria to written vignettes of 100 elderly people identified in clinics or community surveys. Subjects ranged in type from cognitively intact to severely demented and many were also frail, partially sighted, or deaf. This paper concerns reliability within and between centers, and the relationship between reliability and factors such as diagnostic criteria, dementia severity, and respondents' clinical characteristics. Within-center interrater reliability was high, more so for "yes-no" DSM-III-R diagnoses than the multi-level CDR. Between-center rates were lower but still moderate to good. Concordance was lower for intermediate dementia levels than for no dementia and severe dementia. Physical disability made an additional contribution to uncertainty but deafness, poor vision, anxiety, and depression had no discernible effects. Reliability levels are likely to be lower in representative aged populations than in carefully selected clinical groups.

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PubMed1992

Methodological problems with diagnosis of dementia in community surveys: the choice of items to study higher functions.

The 'global' character of dementia distinguishes it from other organic syndromes but in community surveys memory impairment is the predominant early symptom and the aphasia, apraxia and agnosia triad characteristic of dementia of Alzheimer type disease (DAT) may be hard to demonstrate. Both the Mini-Mental State (MMS) and CAMDEX contain appropriate items but information about how elderly persons in general perform on these tests is limited. This paper examines the relative difficulty of the items in a general practice sample and compares their sensitivity and specificity taking AGECAT organic diagnosis as criterion.

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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↗
PubMed1991

The diagnosis of dementia in the elderly. A comparison of CAMCOG (the cognitive section of CAMDEX), the AGECAT program, DSM-III, the Mini-Mental State Examination and some short rating scales.

The performance of CAMCOG, the cognitive section of the CAMDEX, is compared in a non-random sample of 222 elderly people with diagnoses based on AGECAT and on DSM-III criteria, and with the MMSE and some short rating scales. With a cut-off point of 69/70 and AGECAT organic syndrome as the criterion, the sensitivity of CAMCOG was 97% and the specificity 91%. However, 21% of DSM-III diagnoses of dementia scored above this cut-off; these were mostly mild cases. The correlation between CAMCOG and MMSE scores was 0.87, and the advantage of CAMCOG may be more apparent in longitudinal studies. Multivariate analyses showed that CAMCOG scores are affected by age, sociocultural factors and hearing and visual deficits in addition to dementia, but not by depression. There was a suggestion that individual subsections are differentially affected.

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PubMed1990

Senile dementia of Lewy body type. A clinically and neuropathologically distinct form of Lewy body dementia in the elderly.

A dementing syndrome has been identified in a group of psychiatric cases aged 71-90 years, presenting initially with a subacute/acute confusional state, often fluctuating and associated with visual hallucinations and behavioural disturbances. Clinically, these cases did not meet criteria for a diagnosis of Alzheimer's disease, and many were assigned to the multiinfarct dementia group, although no significant ischaemic lesions were evident at autopsy. Mild extrapyramidal features were apparent in a number of cases but the characteristic clinical triad of Parkinson's disease, i.e., tremor, rigidity, and akinesia, was absent. Detailed neuropathological examination revealed Lewy body formation and selective neuronal loss in brain stem and other subcortical nuclei, accompanied by Lewy body formation in neo- and limbic cortex, at densities well below those previously reported in diffuse Lewy body disease. A variable degree of senile degenerative change was present; numerous senile plaques and minimal neurofibrillary tangles in most cases. Neither the clinical nor the neuropathological features of this group are typical of Parkinson's or Alzheimer's disease, but suggest a distinct neurodegenerative disorder, part of the Lewy body disease spectrum, in which mental symptoms predominate over motor disabilities and lead to eventual psychogeriatric hospital admission. In a sequential series of autopsies conducted on clinically assessed demented patients, neuropathological analysis has indicated that such cases may comprise up to 20% of a hospitalized population of demented old people over the age of 70 years, an observation clearly relevant to the diagnosis and management of dementia in the elderly.

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PubMed1990

Prevalence rates of dementia in an ageing population: are low rates due to the use of insensitive instruments?

The varying prevalence rates of dementia reported in elderly populations may be partly due to the use of different diagnostic measures. In a recent study in which diagnosis was based on the CAPE, a 12-item questionnaire, the prevalence rate for severe cognitive impairment for the age group 75 years or over was lower than previously reported. In the present study, the performance of the CAPE was examined in an elderly general-practice sample with a higher than usual risk of dementia. The study diagnosis was based on a combination of the diagnosis made by the computer program AGECAT and a clinical diagnosis made by the interviewing psychiatrist. Forty-five per cent of patients with definite or probable dementia, as defined, and 100% of those with possible dementia had scores above the cut-point on the CAPE. The sensitivity of the CAPE was low compared with that of other rating scales. It is concluded that the low reported rate with the CAPE is probably due to only the more severe cases being identified. For comparative purposes it is important to know the level of dementia that the instruments used are detecting.

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PubMed1990

Cholinergic and dopaminergic activities in senile dementia of Lewy body type.

Analyses of brain tissue in a recently identified group of elderly demented patients suggest a neurochemical basis for some of the clinical features. Senile dementia of the Lewy body type (SDLT) can be distinguished from classical Alzheimer disease (AD) clinically by its acute presentation with confusion frequently accompanied by visual hallucinations, and neuropathologically by the presence of Lewy bodies and senile plaques (but not generally neurofibrillary tangles) in the cerebral cortex. Reductions in the cortical cholinergic enzyme choline acetyltransferase were more pronounced in individuals with (80%) compared to those without (50%) hallucinations and correlated strongly with mental test scores in the group as a whole. In the caudate nucleus, dopamine levels were related to the number of neurons in the substantia nigra, there being a 40-60% loss of both in SDLT--probably accounting for mild extrapyramidal features in some of these cases--compared with an 80% loss in Parkinson disease and no change in AD. The cholinergic correlates of mental impairment in SDLT together with the relative absence of cortical neurofibrillary tangles and evidence for postsynaptic cholinergic receptor compensation raise the question of whether this type of dementia may be more amenable to cholinotherapy than classical AD.

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PubMed1988

Muscarinic cholinergic receptor subtypes in hippocampus in human cognitive disorders.

Total muscarinic receptor levels, the levels of the subtypes exhibiting high and low affinity for pirenzepine, and the high- and low-affinity agonist states of the receptor were investigated in hippocampal tissue obtained at autopsy from mentally normal individuals and the following pathological groups: Alzheimer's disease, Parkinson's disease, Down's syndrome, alcoholic dementia, Huntington's chorea, and motor-neurone disease. A moderate decrease in the density of both high-affinity pirenzepine and high-affinity agonist subtypes was found in Alzheimer's disease, whereas a trend towards an increase in the overall muscarinic receptor density was apparent in the parkinsonian patients without dementia, mainly due to an increase in the low-affinity agonist state; the differences between the Alzheimer's disease and nondemented parkinsonian cases were highly significant. As previously reported, the levels of both choline acetyltransferase and acetylcholinesterase were markedly reduced in both Alzheimer's disease and Parkinson's disease--with a greater loss of both enzymes in the demented subgroup of parkinsonian patients. Activities of the cholinergic enzymes were also extensively reduced in Down's syndrome, accompanied by a loss of high-affinity pirenzepine binding. There were no significant receptor or enzyme alterations in the other groups studied. These observations suggest that in the human brain, extensive degeneration of cholinergic axons to the hippocampus, as indicated by a loss of cholinergic enzymes, is not necessarily accompanied by extensive muscarinic receptor abnormalities (as might be expected if a major subpopulation were presynaptic). Moreover, the opposite changes in muscarinic binding in Parkinson's and Alzheimer's diseases may be related to the greater severity of dementia in the latter disease.

Acetylcholinesterase↗
PubMed1987

Serum creatine kinase-BB levels and cerebral cortical creatine kinase activity in senile dementia of the Alzheimer type.

A rise in serum creatine kinase-BB (CK-BB) levels has been reported previously in cases of dementia. In the present study the levels of serum CK-BB have been measured in patients clinically assessed to have senile dementia of the Alzheimer's type (SDAT) and in cognitively intact individuals, matched for age, by a specific two-site monoclonal immunoradiometric assay. No significant difference was found between the 2 groups. Total creatine kinase activity in temporal cortex (Brodmann area 21 and 22) was also found to be similar in brains from SDAT or control cases, obtained at autopsy. These results suggest no major change in the permeability of the blood-brain barrier to this enzyme in SDAT patients.

Alzheimer Disease↗
PubMed1987

Nicotinic receptor abnormalities in Alzheimer's and Parkinson's diseases.

The status of cholinergic receptors in dementia is related to the question of potential cholinergic therapy. Whilst muscarinic receptor binding is generally reported to be normal or near normal, findings are reported which indicate substantial reductions of hippocampal nicotinic (high affinity nicotine) binding (occurring in conjunction with decreased choline acetyltransferase) in both Alzheimer's and Parkinson's but not Huntington's disease. A further indication that nicotinic receptor function may be abnormal in Alzheimer's disease is the extensive loss of an endogenous compound, detected for the first time in human brain, which inhibits normal nicotinic binding. Both receptor binding and the inhibitor are also substantially decreased with increasing age in the normal hippocampus.

Adult↗
PubMed1987

Correlation between the 37-item mental test score and abbreviated 10-item mental test score by psychogeriatric day patients.

Groups of organically and functionally mentally ill psychogeriatric day patients were assessed by the 37-item Roth-Hopkins test and the abbreviated ten-item Roth-Hopkins test. The scores correlated highly, correlation being equally good for both diagnostic groups. Among the functionally ill and the mild organically ill, scores improved between first and second test. The quicker, better tolerated ten-item test is a useful test of mental impairment for psychogeriatric patients in the community, as well as in institutional care.

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PubMed1986

Aluminosilicates and senile plaque formation in Alzheimer's disease.

Aluminium and silicon were found to be colocalised in the central region of senile plaque cores in studies with energy dispersive X-ray microanalysis. The distribution of these elements was similar in cores isolated from the cerebral cortex of patients with senile dementia of the Alzheimer type and in cores studied in situ from tissue sections from the cerebral cortex of presenile and senile patients with Alzheimer's disease, and elderly, mentally normal patients. High-resolution solid-state nuclear magnetic resonance techniques showed aluminium and silicon to be present as aluminosilicates. The presence of aluminosilicates at the centre of senile plaque cores contrasts with the distribution of other inorganic constituents and suggests that they may be involved in the initiation or early stages of senile plaque formation.

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