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.

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) [1] and CAMDEX [2] 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 [3] organic diagnosis as criterion.

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.

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.

insonism has been reported; that patient also had pyramidal signs.4A further patient exhibited dopa-responsive tremor and facial impassivity during recovery from a more typical presentation of pontine myelinolysis with stupor, abnormal eye movements and tetraparesis.'Pathological changes in the basal ganglia have been well documented in typical cases of pontine myelinolysis,6 and it has been suggested that the pontine lesion masks the extra-pontine clinical features.In our case the large lesion in the pons was clinically silent.MRI is clearly the investigation of choice in patients presenting with neurological syndromes associated with hyponatraemia; subclinical or clinically atypical pontine myelinolysis may be more common than is currently realised.

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.

A subsample (N=204) of a consecutive series of 378 general practice patients aged 70+, previously given the Mental Function Test (MFT) and reported to show a prevalence of dementia of 0.8% (Jachuck et al., 1986), was followed and survivors retested three years later. Dementia was categorized as definite, probable, possible or absent, based on AGECAT and on clinical diagnoses using ICD ‐10 criteria. The diagnoses were checked against patients' scores on the CAMCOG, MMSE, AMT, CAPE and Blessed Dementia Scale, and test‐retest differences on the MFT were noted. Patients who could not be interviewed were reassessed from their first MFT scores and the practice's research records. The MFT's performance and ability to predict death or dementia were examined. The prevalence of definite/probable dementia in the original sample is retrospectively reevaluated as about 11%. The rate in the general population aged 70+ is tentatively estimated after age adjustment to be approximately 9%, similar to that reported earlier (Kay et al., 1970). The age‐specific rates approximate to those derived from analysis of published data (Jorm et al., 1987). It is concluded that the original estimate was too low. The prevalence of dementia among the Newcastle elderly does not appear to have fallen.

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.

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.

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.