Biomedical subjects

R Meares

Publications and source records attributed to R Meares.

At least 55 records · Page 3Linked to original sources

PubMed1989

Regional cerebral blood flow measurements in the diagnosis of dementia.

The Xenon-133 regional cerebral blood flow technique (rCBF) was used to assess cortical perfusion in a group of 15 elderly patients (mean age = 79.1, SD = 8.7) with a probable diagnosis of Dementia of the Alzheimer type (DAT). Nine had mild DAT and six were in the moderate stages of DAT. These patients were compared with 15 age and sex matched normal elderly controls (mean age = 75.1, SD = 5.6). RCBF was measured in each patient and control at rest with eyes closed. The DAT patients had significantly lower mean global CBF than normal controls (t = -4.63, p less than 0.0001). In addition, a further 15 normal elderly subjects aged 60 to 92 were assessed and combined with the original 15 to allow calculation of a normal range of rCBF for elderly individuals. Seventy-three per cent of the DAT patients fell below the lower limit of the normal range (39.3 - 59.3 ISI units). These results show the possible usefulness of rCBF as an aid in the diagnosis of early DAT.

Aged↗

PubMed1989

The P300 event-related potential and regional cerebral blood flow in patients with Alzheimer's disease.

A number of studies have reported that an abnormal delay in the latency of the P300 event-related potential (ERP) is characteristic of the majority of patients with a dementing process. Another body of research suggests regional cerebral blood flow (rCBF) is significantly reduced in Alzheimer's disease (AD). No previous study has compared the effectiveness of these 2 measures in identifying the same patients with AD. Furthermore, most of the studies on which the above findings are based examined patients in the moderate to severe stages of the disorder. In this study we examined P300 latency and rCBF in 10 patients with mild to moderate Alzheimer's disease, and compared their responses with those of normal subjects of similar age. The P300 component was not evident in 2 of the patients: the remaining 8 had a latency within normal limits for their age. On the other hand, 8 of the patients had abnormally reduced rCBF. These results suggest rCBF measures may be useful for identifying AD in its early stages.

Aged↗

PubMed1989

The relationship between reaction time and latency of the P300 event-related potential in normal subjects and Alzheimer's disease.

The latency of the P300 event-related potential is though to reflect the time it takes to conclude that a task-relevant stimulus has been presented, i.e. it is an index of cognitive processing time. Reaction time (RT) also reflects cognitive processing time, but additionally reflects the time taken physically to respond to the stimulus. If serial models of information processing are correct, then the P300 latency must be less than RT, and a positive correlation between the 2 measures is to be expected. We examined these hypotheses in 100 normal subjects aged from 18 to 92 years. The P300 component elicited via a 2-tone discrimination task, and RT to the task-relevant tones was measured simultaneously. The resulting correlation between these measures was weak (r = 0.26, p greater than 0.05), and there were instances in which RT preceded the P300 latency. These results are consistent with parallel rather than serial models of information processing. Fifteen patients with Alzheimer's disease were also examined. Three had an abnormally delayed P300 latency, and 7 had abnormally delayed RTs compared with age-matched controls. Simultaneous measurement of the P300 latency and RT may thus help resolve whether dysfunction is evident in neuronal networks concerned with stimulus evaluation or in those concerned with response execution.

Adult↗

PubMed1988

The P300 event related potential component in the diagnosis of dementia.

Several studies have suggested that delays in the latency of the P300 ERP component are highly sensitive and specific to dementia and that ERP measurements may become a useful clinical tool in aiding diagnosis. This study examines the sensitivity of P300 measurements to dementia and addresses several methodological issues that limit previous research. Twenty-four patients with dementia diagnosed according to ICD-10 criteria were compared with 100 normal controls, 31 of whom were older than 60. An auditory oddball paradigm was employed to elicit the P300. Mean P300 latency did not differ significantly between the two groups. When individual subjects were examined only 13% of patients with dementia fell outside the two standard error band of the regression of P300 latency on age derived from controls. Thus, this study has not demonstrated clinically useful abnormalities of the P300 component in dementia.

Adolescent↗

PubMed1988

On self-boundary: a study of the development of the concept of secrecy.

The child's developing concept of a 'boundary' between an inner world of 'self' and an outer world 'non-self' is central to a number of systems of psychodynamic theory. The notion of boundary is also essential to Piaget. Despite the evident importance of the subject, there have been few attempts to discover the age at which this concept emerges. This study of 40 urban Australian children uses the development of the concept of secrecy as a marker. Most children attained this concept during the fifth year of life.

Australia↗

PubMed1987

An investigation of patients presenting with multiple physical complaints using the illness behaviour questionnaire.

The Illness Behaviour Questionnaire was used to determine whether three groups of patients who had presented with multiple symptoms in different treatment settings (Briquet's syndrome, post-viral fatigue syndrome, and a heterogeneous general practice group) could be differentiated from one another and from a mixed group of psychiatric patients on the basis of their abnormal illness behaviour. All groups completed a version of the Perley and Guze diagnostic criteria for Briquet's syndrome. The three groups presenting with multiple symptoms were more similar to each other than to the psychiatric patients. The results suggest that patients presenting with multiple symptoms include similar populations of patients who are poorly distinguished using current schemes of classification.

Adult↗

PubMed1987

Evoked response potentials and regional cerebral blood flow in somatization disorder.

Somatization disorder (SMD) is a chronic condition characterized by multiple complaints which are not due to any apparent organic illness but frequently involve pain. This study employs computer-aided imaging technologies to examine brain function in thousandths of a second (event-related brain potentials) and over a number of minutes (regional cerebral blood flow). Fourteen patients with SMD and 14 normal controls were investigated. Results from both studies suggest that patients with SMD have a dysfunction in the processes of attention, compared to normal controls.

Adult↗

PubMed1987

The secret and the self: on a new direction in psychotherapy.

This paper briefly describes some principles of a self-psychology, this term being used in a broad sense. As a heuristic device, the theme of evolution of self is woven about the formation of its boundary. Boundary formation is seen to be fostered by therapeutic responses that 'match' inner states. This notion is linked to other means of enhancing a sense of 'innerness'. They include a respect for the distinction between the realms of public and private, a potentiation of the 'ownership' of experience and the use of certain forms of language. Through a consideration of the concept of 'the secret', self-psychology is contrasted with the traditional or ego psychologies. What emerges is a therapeutic approach to personality disorder that resembles important aspects of the work of Kohut and Winnicott, the major contributors to this developing body of theory.

Ego↗

PubMed1987

Magnetoencephalography: locating the source of P300 via magnetic field recording.

A description is given of the theory and instrumentation involved in measuring magnetic fields of the brain. The magnetic counterpart of event-related potentials are capable of locating more accurately the generators of these electrical signals. Preliminary results of the first application of magnetoencephalography in Australia are presented. These localize the generator of the auditory P300 event-related potential component to the temporal cortex.

Adult↗

PubMed1986

The differential diagnosis of dementia using P300 latency.

The P300 component was elicited by an auditory oddball paradigm in 55 normal adults from a wide age range: 19 patients with dementia, 17 patients with depression, and 15 patients with schizophrenia. Normal P300 latency at a given age was predicted by using an age regression equation that had been calculated on the basis of the entire normal sample. Using this procedure, an abnormal delay in latency (greater than 2 SD) was found in approximately 80% of the dementia patients. However, when normal latency was predicted with a slightly greater degree of reliability according to separate equations for adults younger and older than 63 years, an abnormal delay in P300 was found to be less sensitive and specific to dementia. Suggestions for enhancing the diagnostic utility of the P300 component are proposed.

Adolescent↗

PubMed1986

Auditory evoked response potentials in somatization disorder.

Event related potentials to frequently and infrequently occurring tones were recorded from 15 patients with somatization disorder, 10 patients with anxiety disorders and 15 normals. P3 component responses were of normal latency and amplitude in the somatizers, which suggests they had no apparent difficulty with certain aspects of processing novel, task-relevant stimuli. However, their N1 component responses to the frequent tones, which subjects had been instructed to ignore, were enhanced relative to each of the other groups. Moreover, there was no difference in N1 amplitude to the two types of tones among the somatizers, whereas each of the other groups had significantly larger N1 amplitudes to the infrequent tones. These preliminary results may suggest that somatization disorder is associated with an impaired ability to filter out and not respond to relatively meaningless afferent stimuli.

Adult↗

PubMed1986

The prediction of normal P3 latency and the diagnosis of dementia.

The relationship between age and the latency of the P3 (auditory evoked response potential) component was best described in 55 normals aged 15-89 by separate linear regression equations for those younger and those older than 63. Twelve out of 19 patients with dementia had P3 latencies at FZ and CZ which were delayed by more than two standard errors from the normal latency for their age predicted using the above equations, and were thus correctly identified. However, an equation calculated across the entire adult age range provided a better patient identification rate. The potential usefulness of P3 measures in clarifying the nature of cognitive impairment in dementia is discussed.

Adolescent↗

PubMed1986

On the ownership of thought: an approach to the origins of separation anxiety.

Separation anxiety is of major clinical significance, particularly in the management of personality disorder. Despite important advances, the origins of the phenomenon remain unclear. The hypothesis put forward here is that it is a manifestation of incomplete self-boundary formation. An elaboration of this idea, which has a Piagetian basis, provides an organizing framework for a therapeutic approach which is consistent with the empathic stance of the Kohutians and the recommendations of Winnicott.

Anxiety↗

PubMed1986

P300 and the effects of aging: relevance to the diagnosis of dementia.

A tone discrimination task was used to elicit the P300 component of event related potentials in 55 normal subjects aged between 15 and 89 years. The age/latency relationship in the total sample was significant, but contrary to the reports of some others was statistically better described at CZ by a linear and not a curvilinear age regression function. Adults over 45 had steeper age regression slopes and larger age/latency correlations frontally and centrally than younger adults, but there was no difference in amplitude between these groups. The effect of age on latency seemed slightly more pronounced frontally in older adults, and there was significantly more latency variability in this group. Overall, the age/latency relationship in adults was statistically best described by separate linear age regression functions for adults less than or equal to 45 and greater than 45. It is suggested that latency variability may account for some of the discrepancy in the age/P300 literature, and the clinical implications of this are discussed.

Adolescent↗

PubMed1986

Psychometrics and event-related potentials in the diagnosis of dementia.

This study attempted to increase the reliability of predicting the normal latency of the P3 component in elderly adults. It was hypothesized this would allow a more accurate distinction to be made between normal adults (n = 20) and patients with dementia (n = 19) on the basis of observed P3 latencies. Two models for predicting latency were assessed. The first, which used age alone as a predictor, explained 18% of the normal variation in latency and misclassified 40% of the patients. The second model, which incorporated scores on psychometric tests, explained 74% of latency variation and misclassified 20% of the patients. Scores on the Similarities subtest of the WAIS and the Rey Auditory Verbal Learning Test, however, correctly identified 92% of the patients. This finding casts doubt on the justification of the P3 latency measures to diagnose dementia.

Age Factors↗

PubMed1985

Whose hysteria: Briquet's, Janet's or Freud's?

Somatisation disorder (Briquet's syndrome) is a recent addition to psychiatric nosology. It represents an attempt to describe a syndrome of 'hysteria', the term initially applied to this polysymptomatic disorder by Guze and his colleagues. The manner of identification of this syndrome, however, has been the subject of criticism. This brief review suggests that the ideas of Janet, who worked at Salpetriere 30 to 40 years after Briquet, may provide a more precise approach to diagnosis. Furthermore, his hypotheses about predisposition to this disorder are seen to offer a preliminary way towards its understanding. Recent experimental evidence lends some support to Janet's hypotheses.

Conversion Disorder↗

PubMed1984

Inner space: its constriction in anxiety states and narcissistic personality.

Our sense of existence has a spatial component ( Heidegger 1962, p. 123). For example, descriptions of affect depend upon words such as "high" and "low." Moreover, one's sense of the volume of inner space is mutable. Although experiences of inner space are with us all the time, they are relatively neglected from a theoretical and therapeutic point of view. This paper concerns the possibility that the perceived dimensions of inner space vary with one's mode of thought, which, in turn, changes according to one's relationship with the sensory environment. The most important elements of this environment are clearly social. Constriction of personal space seems to be characteristic of anxiety states and of the narcissistic personality. Some therapeutic implications of this idea are discussed.

Adult↗

PubMed1983

The type A behaviour pattern and physique.

This study examines the possibility that Type A behaviour is related to physique, and thus, is secondary to physique as a risk factor for coronary heart disease (CHD). Scores on a modified version of the 1966 Jenkins Activity Survey were correlated with a number of physical parameters. Age was found to have the highest correlation of -0.177. When the effects of age were adjusted for, only 7.1% of variation in JAS scores was explained by the body measurements used to define physique. In addition, when high and low scorers on the JAS were compared, no significant differences were found between the groups on any of the body measurements. Since this study found no significant relationship between JAS scores and physique, the results do not controvert the supposition that Type A behaviour is an independent risk factor for CHD.

Adult↗