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Biomedical subjects

G W Fenton

Publications and source records attributed to G W Fenton.

At least 37 records · Page 2Linked to original sources
PubMed1992

Anticholinergic drug effects on quantitative electroencephalogram, visual evoked potential, and verbal memory.

Electroencephalographic (EEG) power and coherence spectrum and visual evoked potential (VEP) recordings were made in a group of control subjects on two occasions, a week apart, before and after the subcutaneous administration of either 0.6 mg scopolamine (hyoscine-hydrobromide), a centrally acting anticholinergic drug, or 0.5 mg methscopolamine nitrate, a peripherally acting anticholinergic drug. After scopolamine administration, the EEG power spectrum significantly slowed and EEG coherence at the alpha and beta frequencies decreased. Left interhemispheric coherence increased at 1 Hz and 3-7 Hz. Methscopolamine had no significant effect on the quantitative EEG. The latency of the major positive components of the VEPs, to both flash and pattern stimuli, were not significantly affected by either drug. Verbal memory was significantly reduced after scopolamine. The results suggest that previous reports of scopolamine-induced changes in the EEG power spectrum and in verbal memory can be attributed to the central action of the drug rather than to peripheral side effects.

Adult↗
PubMed1991

The psychobiology of minor head injury.

Twenty-six consecutive admissions to an accident and emergency unit with minor head injury were examined. This was defined as a head injury warranting brief in-patient overnight stay but with a post-traumatic amnesia of less than 12 hours. Each patient had a neurological examination, a post-traumatic symptom check list completed, EEG power spectra analysis and auditory brain stem-evoked potential recordings, and a four-choice reaction-time measurement. These assessments were repeated six weeks later. Six months after the head injury a symptom check list was completed and four-choice reaction time measured again. Post-traumatic symptoms are persistent in half of all patients at six weeks and six months follow-up. The EEG power spectra showed a significant change in theta power between the first recording and the second one at six weeks, with relative reduction being noted. Approximately half of all patients had significant delays in brain stem conduction time at day 0. There was a trend towards a decrease in brain stem conduction time at six weeks, though in almost half the brain stem conduction time still remained abnormal at six weeks. Head-injured patients had prolonged choice reaction times at day 0 with serial improvement between then and six months, though the values at six weeks were still significantly longer than healthy controls. It is suggested that these findings reflect both cortical and brain stem damage following minor head injury, the brain stem damage being more persistent. There appear to be three patterns of recovery, half recovering within six weeks, a minority persisting over six months with persisting brain stem dysfunction and less than a third showing an exacerbation of symptoms with no evidence of brain stem dysfunction, the exacerbation being possibly a consequence of psychological and social factors.

Adolescent↗
PubMed1990

Assisted natural recovery from alcohol problems: effects of a self-help manual with and without supplementary telephone contact.

One hundred and seven problem drinkers responding to a newspaper advertisement were randomly assigned to groups receiving: (1) a general advice and information booklet; (2) a behaviourally-based self-help manual; (3) in addition to the manual, an opportunity to make progress reports to a telephone answering service; and (4) in addition to the manual, an opportunity to make telephoned progress reports to an interviewer. Eighty-seven (81.3%) respondents were successfully followed-up and collateral information was available for 54 (61.1%) of these. Results showed a higher proportion drinking above recommended limits at six months follow-up in the control group (78%) than in the groups receiving the manual (53%). There were no significant differences due to presence or type of telephone contact and poor use was made of the opportunity for telephone contact. Findings justify the widespread promotion of self-help materials as a means of assisting the natural recovery process among problem drinkers.

Adolescent↗
PubMed1990

A quantitative histological study of early clinical and preclinical Alzheimer's disease.

Brains from 70 unselected general hospital necropsy cases aged 60-95 years were surveyed histologically for changes of Alzheimer's disease using Congo Red-Gallocyanin preparations. Counts were made of neurofibrillary tangles in two areas of the neocortex, the hippocampal formation and the substantia innominata. Neurons were counted in the subiculum of the hippocampus, the substantia innominata and the locus coeruleus. In addition, a retrospective enquiry was made concerning the mental health of the patients in the study; cognitive performance was graded on the Global Deterioration Scale (GDS 1-7). Four cases (5.7%) had clinical and pathological changes amounting to early Alzheimer's disease. Tangles were very numerous in all areas and there was a 30% deficit or more of neurons in at least two of the structures counted. Although the diagnosis of Alzheimer's disease was not recorded during life, all had shown signs of early cognitive decline (GDS grades 3-6). A further six cases (8.6%) showed excessive tangle accumulation which may represent preclinical Alzheimer's disease. Tangles were present in the temporal neocortex (Brodmann area 22), whereas they were absent in the remainder of the survey. Tangle density in the hippocampal formation (greater than 50 tangles in a 10 microns section) was also above the baseline level of the majority of cases. However, neuron loss was not widespread in these cases and none had shown evidence of cognitive impairment. The findings confirm that the early stages of Alzheimer's disease commonly occur amongst general hospital necropsies. The emergence of clinical signs of dementia appears to be related to the loss of a critical volume of neurons and not to tangle accumulation alone.

Aged↗
PubMed1989

Musical hallucinations in a deaf elderly woman.

Musical hallucinations had caused an 86-year-old deaf woman to become anxious and depressed. She was admitted, and tranquilizing and hypnotic drugs afforded some slight improvement. The use of her hearing aid to increase ambient noise levels reduced the intensity of the hallucinations, and the patient improved.

Aged↗
PubMed1987

Anticonvulsant medication in a mental handicap hospital: 1972-1982.

The prescription sheets for all patients in a mental handicap hospital on one day in 1972 and on the same date in 1982 were examined to identify trends in anticonvulsant medication over a 10-year period. There was a reduction in size of the hospital population associated with fewer very young and milder handicapped persons. Prescription of anticonvulsants fell slightly during the decade under study with a dramatic fall in the use of phenobarbitone, and a parallel increase in the prescription of carbamazepine. Other changes included the use of sodium valproate in a significant minority of patients and the occasional use of clonazepam in 1982, while phenytoin remained a first-rank anticonvulsant throughout the period under review. The proportions of patients on polytherapy did not change over the 10-year period, though the contribution of phenobarbitone to the combined drug regimes was significantly reduced.

Anticonvulsants↗
PubMed1986

The contingent negative variation (CNV) to fear-related stimuli in acquisition and extinction.

Contingent Negative Variation (CNV) in anticipation of phobic and neutral slide material was recorded in Acquisition of a learned association between tone pitch and slide type, and in Extinction (following removal of slide presentation). In phobic volunteers, no clear CNV differentiation between 'phobic' and control condition was apparent in either Acquisition or Extinction. For Control subjects, a different pattern entirely has been demonstrated, with anticipation of the neutral condition giving rise to a larger CNV than anticipation of the 'phobic' condition (in Acquisition). In addition, Extinction led to a reversal of this CNV amplitude relationship, with the tone previously associated with the phobic slide producing a DC-shift which was larger than that following the tone previously paired with the neutral slide. The results are compatible with a dynamic model of CNV generation according to which CNV amplitude is positively related to an expectancy for reward or non-punishment but inversely related to an expectancy for punishment or non-reward.

Adult↗
PubMed1984

Assessment of clinical psychiatric skills in final-year medical students: the use of videotape.

Sixty final-year medical students had their clinical performance in psychiatry assessed by the following three methods: a multiple choice questionnaire based on a series of short videotaped interviews with psychiatric patients; the examination of a traditional long 'case' with presentation of the history, mental state findings and formulation about diagnosis and management to a panel of three examiners; and a conventional oral examination about the principles and practice of psychiatry with a different trio of examiners. The total mark on the videotape session correlated significantly with the combined clinical and oral marks. There was also a significant positive correlation between the total video marks and the individual clinical marks, but none between the marks obtained during the video and oral components of the examination. However, the significant positive correlations between the video marks and those of the clinical examination were modest and only accounted for not more than 14% of the variance. Inspection of the distribution of correct answers to the videotape questions shows that students do best in identifying mental state symptoms and signs and in choosing the correct diagnosis. They do less well in the areas of aetiology and treatment. Indeed, optimal performance in the latter distinguishes those who do well in the clinical/oral examination from those whose performance is mediocre. The significance of these findings to the teaching and assessment of psychiatric skills in medical students is discussed.

Education, Medical, Undergraduate↗
PubMed1984

Measurement of reaction time following minor head injury.

A four-choice reaction time test was carried out on 45 minor head injury cases, 24 hours after the injury and 6 weeks later. Twenty-eight subjects were re-tested after a six month interval. Reaction time measures were also obtained in a matched, general practice control group. The concussion cases displayed significantly poorer performances than the matched controls in four measures, at day 0 and at 6 weeks. The patients also showed serial improvement in these measures up to six months after the injury, when their scores excelled those of the matched controls.

Adolescent↗
PubMed1984

The contingent negative variation, personality and antisocial behaviour.

Using a classical click/flash paradigm the contingent negative variation (CNV) was recorded from 60 consecutive male admissions to Broadmoor Hospital. Clinical and psychometric Minnesota Multiphasic Personality Inventory (MMPI) assessments were made independently of the electroencephalography (EEG) data. A trend for higher amplitude CNV's to be recorded from patients with a clinical diagnosis of antisocial (psychopathic) personality was observed. Patients with a Mental Health Act diagnosis of psychopathic disorder had significantly higher voltage CNV's than those in the mental illness category. These CNV differences were only found in the primary (non-anxious, sociable) psychopaths. Secondary (neurotic, unsociable) psychopaths did not differ from staff controls. A positive association between CNV voltage and the personality factor of sociability(sociable-shy dimension) was observed. A weak, negative correlation between CNV amplitude and impulsivity (impulsive-controlled dimension) was also apparent. All subjects showed an habituation effect across trials. No difference in response variability between successive series of trials was apparent in any of the patient groups.

Antisocial Personality Disorder↗
PubMed1984

The electroencephalogram in psychiatry: clinical and research applications.

The main clinical value of the EEG in psychiatry is as a non-invasive tool for the investigation of organic mental syndromes and epilepsy. Predictions that CT scanning would make the EEG redundant have not been fulfilled. Indeed, the 2 instruments complement each other, the EEG being a measure of function and the CT scan a reflection of brain structure. Both are proving useful in the investigation of dementia, providing different but complementary information about the extent and progress of the disease. Quantitative methods of EEG analysis using laboratory computers are now readily available. Significant changes in both the EEG background activity and event related potentials have been clearly demonstrated in the functional psychoses. These are not specific for any diagnostic condition. This implies that they reflect changes caused by the impact of the psychotic mental state on the individual's cognitive processes and level of arousal. The challenge for the future is to develop models of the relationship between the electrical events and underlying cognitive processes. Some progress has been made concerning the ERP changes in selective attention and in phobic disorder. The computerized EEG has a clearly established place in the investigation of drug action, by-passing the blood brain barrier and providing direct access to brain activity. Clearly this work may prove useful in the study of the effects of drug induced change on neurotransmitter systems. The EEG study of all night sleep in patients with functional psychiatric disorders has not lived up to the early expectations of workers in the field. Nevertheless the studies of insomnia and hypnotic drug effects have had valuable practical implications.

Adolescent↗
PubMed1980

EEG spectral analysis in schizophrenia.

Four channels of EEG (T4-T6, P4-02, T3-T5, P3-01) were recorded from several groups of control subjects and schizophrenia patients on analogue tape. They were later digitized and analysed by computer; power spectra were computed for 30 second epochs of EEG per channel; eyes closed, eyes open. No difference between normal controls and neurotic in-patients was apparent. An acute schizophrenic group had less alpha power, this change being confined largely to the temporal areas. A chronic outpatient sample showed less alpha and beta power, while chronic long-stay schizophrenic patients had an excess of delta power. The changes in both chronic patient groups were diffuse rather than local.

Acute Disease↗
PubMed1978

The contingent negative variation in antisocial behaviour: a pilot study of Broadmoor patients.

Using a classical click/flash paradigm, the CNV was recorded from the following three groups of subjects at Broadmoor Hospital: (1) 14 'psychopathic' patients selected by use of the 4/9 MMPI profile and confirmed by independent clinical diagnosis; (2) 15 'non psychopathic' patients, all psychotic and mainly schizophrenic; (3) 14 healthy staff control subjects. All three groups were matched for age and sex; the two patients groups were also matched for length of stay. Two series of 32 paired stimuli were used, separated by an interval of 30 minutes. The mean CNV voltage was significantly lower in the 'non-psychopathic' patients. The amplitude of the 'psychopath's' CNV response did not differ significantly from that of the staff controls, but the response variability between the first and second series of trials was much greater in the 'psychopathic' patients than in the other two subject groups. The 'psychopathic' subjects tended to show more rapid initial development of the CNV.

Adult↗