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W J Muir

Publications and source records attributed to W J Muir.

67 records · Page 4Linked to original sources
PubMed1991

Magnetic resonance imaging in schizophrenia: altered brain morphology associated with P300 abnormalities and eye tracking dysfunction.

This study was designed to investigate whether auditory P300 event-related potential and smooth pursuit eye-movement abnormalities in schizophrenia are associated with brain structural changes measured using magnetic resonance imaging (MRI). Serial coronal MRI scans obtained from 31 schizophrenic subjects and 33 volunteer controls were analysed by a rater who had no knowledge of the subjects' diagnoses. The brain areas measured bilaterally were the temporal lobe, hippocampus, amygdala, parahippocampal gyrus, head of caudate, cingulate cortex, frontal cortex, and the lateral ventricles. The area of the third ventricle, the thickness of the corpus callosum, and the intracranial area were also measured. Auditory P300 and eye tracking performance were recorded on all subjects. There was a significant increase in the latency and a reduction in amplitude of the P300 in the schizophrenic group. Only in the schizophrenic group was P300 latency correlated negatively with the area of the right and left cingulate cortex and positively with the difference in size between the right and left amygdala. In the subgroup of schizophrenic subjects whose P300 latency was greater than 2 standard deviations above the control mean, the area of the left cingulate cortex was significantly smaller than in controls, and the absolute right-left difference in the area of the amygdala was significantly increased. Eye tracking dysfunction in schizophrenia was not related to changes in the amygdala or cingulate cortex but was significantly correlated with enlargement of the lateral ventricles. Schizophrenic subjects with poor eye tracking had significantly larger lateral ventricles than controls. Eye tracking dysfunction, but not P300 abnormality, was correlated with the severity of both positive and negative symptom of schizophrenia. These findings demonstrate that psychophysiological abnormalities are associated with altered brain structure in schizophrenia.

Arousal↗
PubMed1991

Auditory P300 and eye tracking dysfunction in schizophrenic pedigrees.

Several psychophysiological abnormalities associated with schizophrenia have been proposed as genetic trait markers of vulnerability to the disorder. Smooth pursuit eye tracking dysfunction and abnormal long latency event-related potentials are the most promising candidates. Both are independent of the effects of psychotropic medication or mental state at the time of testing, and twin studies demonstrate that each has a high level of heritability. Having recorded smooth pursuit eye tracking and event-related potentials in 20 high-density schizophrenic families, we find abnormalities in one or both measures in most of the families studied. The abnormalities, when present, occur in the family members with schizophrenia and other forms of functional psychosis, and they have a bimodal distribution with approximately half the nonschizophrenic relatives also showing eye tracking dysfunction and/or abnormal event-related potentials. Some of these relatives had psychiatric symptoms; others were normal. Our results suggest that psychophysiological examination can help to clarify the boundaries of schizophrenia spectrum disorder. By helping to decide the phenotypic status of nonschizophrenic family members, this should increase the power of DNA linkage studies.

Acoustic Stimulation↗
PubMed1991

Long-latency auditory event-related potentials in schizophrenia and in bipolar and unipolar affective disorder.

Long-latency auditory event-related potentials were examined in 96 subjects with schizophrenia, 99 with bipolar affective disorder and 48 with major depressive (unipolar) disorder, and compared with 32 in-patient and 213 normal controls. The latency of the P3 component was significantly greater in the schizophrenic and bipolar subjects compared to other groups. The difference was stable with respect to clinical state at the time of testing and was not due to age differences or the effect of psychotropic medications. The results support the clinical distinction between bipolar and unipolar affective disorders, but also show that P3 change is not specific to schizophrenia and found in bipolar but not unipolar affective disorder.

Adolescent↗
PubMed1990

Perceptual and physiological dysfunction in depression.

P300 responses to emotive words of different hedonic tones were assessed in depressed patients (unipolar major), patients recovered from the same type of depression and normal controls. Depressed patients showed a smaller amplitude of P300 in response to negatively toned words than to positive words; normal controls showed the opposite pattern and recovered patients showed a pattern of response which resembled that of depressed patients. The experimental trials comparing responses to negative and positive stimuli in relation to neutral words showed significant differences for negative as compared with neutral stimuli, but not for positive as compared with neutral stimuli. Latencies of P300 did not differentiate depressed patients from normal controls. The results are discussed within the context of the 'expectancy' theory of information processing.

Adult↗
PubMed1989

Auditory P300 does not differentiate borderline personality disorder from schizotypal personality disorder.

The P300 response to an auditory two-tone discrimination task has previously been reported to have prolonged latency and reduced amplitude in schizophrenia and borderline personality disorder. In this study, P300 was recorded from 23 subjects with borderline personality disorder, 12 subjects fulfilling criteria for both borderline and schizotypal personality, and 11 subjects with schizotypal personality. The mean P300 latency was similar in each of these groups and was significantly longer than in 32 patients with neuroses and other personality disorders and 74 nonpatient controls. These findings suggest that borderline and schizotypal patients share a similar abnormality in auditory stimulus evaluation and question whether or not these disorders are separate.

Adolescent↗
PubMed1988

The development of Alzheimer's disease in Down's syndrome assessed by auditory event-related potentials.

Several studies have reported changes in auditory event-related potentials in patients with Alzheimer's type dementia. These include an increase in latency and a reduction in amplitude of the P300 (P3) response, a late positive component generated about 300 ms after an unexpected stimulus. Alzheimer's type dementia is an almost invariable acompaniment of ageing in Down's syndrome. This study was designed to assess the usefulness of the auditory P300 response as a measure of the onset of dementia in Down's subjects, who because of poor language development may be difficult to assess by psychological tests. Auditory event-related potentials were recorded from 89 Down's subjects, aged 16-66 years. A control group of 29 mentally retarded subjects with fragile-X syndrome and 83 normal volunteer controls were also tested. Clinical psychological testing found evidence of dementia in 16 Down's subjects and none with fragile-X. Furthermore, in the Down's population but not the fragile-X or control groups, there was a marked increase in P300 latency with age starting around 37 years. In controls, the effect of age on P300 latency became significant some 17 years later around the age of 54 years. The premature effect of age on P300 in Down's syndrome was due to the prolonged P300 latency in the 16 subjects showing signs of dementia. It was confirmed that P300 latency increase reflects the development of Alzheimer's dementia in Down's subjects.

Adolescent↗
PubMed1988

Auditory P300 response in the assessment of Alzheimer's disease in Down's syndrome: a 2-year follow-up study.

Sixty-five subjects with Down's syndrome were followed up and retested 2 years after the initial recording of auditory P300 (P3) event-related potential described in a companion paper (Blackwood et al., 1988). The number of subjects showing clinical evidence for Alzheimer's type dementia had increased by a further 14%. In subjects showing clinical deterioration over a period of 2 years, 78% (7/9) had an increase in P3 latency which was three standard deviations or greater than the group mean. None of the 20 fragile-X group retested showed significant change after 2 years. The results suggest that P3 change may be a sensitive index of the onset of Alzheimer's type dementia in Down's syndrome.

Adolescent↗
PubMed1987

Auditory P300 in borderline personality disorder and schizophrenia.

Using three sets of clinical criteria to define borderline personality disorder (BPD), P300 (P3) and other long-latency auditory event-related electroencephalographic potentials were measured in 22 subjects with BPD, 32 subjects with other personality disorders, 29 schizophrenics, 22 depressives, and 74 volunteer controls. The patients with BPD were found to differ from patients with nonborderline personality disorders, having a longer P3 latency and smaller P3 amplitude. Long-latency event-related potentials were similar in the BPD and schizophrenic groups and did not differentiate patients with BPD with a concurrent diagnosis of schizotypal personality disorder from those without schizotypal personality disorder. The P3 latency and amplitude changes distinguished the BPD and schizophrenic groups from normal controls, those with major depressive disorder, and those with nonborderline personality disorders. These findings suggest that though some patients with BPD may have depressive symptomatology, they share with schizophrenics a dysfunction of auditory neurointegration.

Adolescent↗
PubMed1986

A psychiatric study of idiopathic oedema.

Twenty-five women with idiopathic oedema and twenty-five women attending gynaecology clinics were assessed by means of a standardised psychiatric interview, an interview on dietary habits, and a specially designed interview on current health. The patients with idiopathic oedema were significantly more depressed and anxious, with a trend towards widespread neurotic symptoms. There was no evidence that diuretic or laxative abuse is an important aetiological factor. In many patients with idiopathic oedema excessive fluid retention may be related to the neuroendocrine abnormalities associated with psychiatric illness.

Adult↗
PubMedDate not supplied

Mitochondrial sequence variants in patients with schizophrenia.

To investigate whether mitochondrial mutations underly susceptibility to schizophrenia, we sequenced the mtDNAs of two unrelated Swedish patients with schizophrenia and low cytochrome oxidase activity and two maternally related Scottish patients from a family with suspected maternal inheritance of the disease. We found five substitutions in coding regions that have not previously been described as polymorphisms. These new substitutions were studied in 81 schizophrenic patients and five control groups from Sweden and Scotland and found to differ in frequency between populations, emphasizing the importance of using large and well-defined control materials for evaluating the association of mtDNA mutations with disease. The results do not lend strong support to the association of a particular mtDNA substitution with increased risk for schizophrenia. However, the trend towards a higher frequency of substitutions in the patients deserves further attention.

Conserved Sequence↗