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Biomedical subjects

A M Fox

Publications and source records attributed to A M Fox.

At least 37 records · Page 2Linked to original sources
PubMed1993

Allusive thinking in parents of schizophrenics. Meta-analysis.

Romney (J. Nerv. Ment. Dis. 178:481-486, 1990) performed a meta-analysis of studies examining psychometrically assessed "thought disorder" in the relatives of schizophrenics. He concluded that thought disorder was more prevalent in the relatives of schizophrenics than control subjects. The present review focuses on only those studies that measured "allusive thinking" using the Lovibond-Rapaport Object Sorting Test in parents of schizophrenics. Even when the meta-analysis included this more limited number of studies, it demonstrated that the parents of schizophrenics were 2.42 times more likely to obtain high scores on the Object Sorting Test, confirming replication of the original McConaghy (J. Neurol. Neurosurg. Psychiatry 22:243-246, 1959) finding. This effect remained significant when the original study was excluded from the meta-analysis. The predictive strength of parental Object Sorting Test score as a familial risk factor for the development of schizophrenia is discussed.

Family↗
PubMed1993

Risks and benefits of drugs used in the management of the hyperactive child.

Childhood hyperactivity is a common behavioural complaint. The therapeutic options for physicians caring for children with hyperactivity are considerable and varied; current recommendations call for a multidisciplinary approach, including when necessary the use of drug therapy. Central nervous system stimulants are the primary agents used in the therapy of hyperactivity. The majority of children with hyperactivity diagnosed using careful clinical criteria will demonstrate short term benefits in cognitive and behavioural terms, but long term efficacy remains controversial. There appears to be a subset of patients who do not demonstrate a beneficial response to stimulants, although there is controversy as to whether this may be dose dependent. The adverse effects of most concern are suppression of growth, the development of tics and the potential for abuse. Antidepressants and clonidine are useful agents for the therapy of patients resistant to stimulant therapy. Although the most frequent adverse events of antidepressant therapy are associated with the anticholinergic activity of these agents, the most common serious adverse events are associated with antidepressant overdose. Concern has been expressed because of case reports describing an association between antidepressant therapy for hyperactivity and sudden death. A number of other therapies have been used for hyperactivity. Although these therapies may be effective in subsets of patients with hyperactivity, there is little research detailing how to identify patients who might be expected to respond to such treatment.

Antidepressive Agents↗
PubMed1992

Cognitive functioning in excessive drinkers: evidence for dissociable impairments.

This article reviews the evidence for neuropsychological impairments in excessive drinkers. The view that the neuropsychological impairments reflect clinically heterogeneous manifestations of a unitary 'Wernicke-Korsakoff complex' resulting from thiamine deficiency is discounted on the basis of a variety of mediating factors which have been demonstrated to affect the pattern of cognitive abilities and deficits in excessive drinkers. In contrast, this article argues that detailed analysis of the apparent clinical heterogeneity in the cognitive status of these patients may provide a means for determining the most appropriate treatment regime and rehabilitation procedures for an individual. These impairments are applied to a theoretical model of information processing identifying dissociable impairments which have been described as the 'frontal-lobe' and the 'right hemisphere' hypotheses of the effects of alcohol on cognitive functioning. Interpretation of research results in terms of functional characteristics rather than localization characteristics is proposed. Two mediating factors, thiamine deficiency and liver dysfunction, are discussed in relation to their differential involvement in these impairments.

Journal Article↗
PubMed1991

Effects of long-term cannabis use on selective attention: an event-related potential study.

Brain event-related potentials (ERPs) were recorded from nine long-term cannabis users during a complex auditory selective attention task and compared with nine nonuser controls. Stimuli consisted of a random sequence of tones varying in location, pitch and duration. Subjects were instructed to respond to long-duration tones of a particular pitch and location. Cannabis users' task performance was significantly worse than controls. The most striking difference between the ERPs of the two groups was in the greatly enhanced early processing negativity in the user group to short-duration stimuli which matched the target on location only. This is indicative of users engaging in unnecessary pitch processing and thus having difficulty in setting up an accurate focus of attention and in filtering out irrelevant information. The data suggest a dysfunction in the allocation of attentional resources and stimulus evaluation strategies. These results imply that long-term cannabis use may impair the ability to efficiently process information.

Adult↗
PubMed1991

Auditory selective attention and event-related potentials in schizophrenia.

Brain ERPs were recorded in ten unmedicated schizophrenic patients and age- and sex-matched healthy controls during a multidimensional listening task. Patients showed a marked reduction in a long-duration attention-related negative ERP component, termed 'processing negativity' (PN), which was elicited by attended stimuli. The amplitude of PN was significantly correlated with SANS and SAPS scores of schizophrenic symptoms. The P300 component was also reduced in amplitude in patients, and was significantly correlated with SANS ratings of negative thought disorder. These findings provide neurophysiological evidence of impairment in the maintenance of selective attention and the cognitive processes associated with target detection among schizophrenic patients. The reduced PN in schizophrenics implicates frontostriatal pathways in the aetiology of attentional deficits in schizophrenia.

Adult↗
PubMed1990

Event-related potential indices of selective attention and cortical lateralization in schizophrenia.

Auditory event-related potentials (ERPs) from a multidimensional selective attention task were recorded from 10 unmedicated schizophrenic patients and 10 age- and sex-matched healthy controls. Tone pip stimuli varying on the dimensions of pitch (high or low) and location (left or right ear) formed four 'channels' of stimuli: left low, left high, right low, and right high. The pitch difference was considerably more difficult to discriminate than the location difference. Subjects were instructed to pay attention to a designated channel and press a button whenever they detected a long-duration, rare target tone that occurred amongst frequent short-duration standard tones. There were a number of differences between unmedicated schizophrenics and controls in processing negativity elicited by standard tones. There was no evidence of hierarchical processing of stimulus dimensions in the early processing negativity component, and the late frontal component was virtually absent in schizophrenics. Furthermore, there was evidence that in schizophrenics the processing of the location dimension was delayed for standard tones having the same pitch as the target. The P300 component to attended target tones was substantially reduced in schizophrenics over parietal sites but there was no difference between the two groups over frontal sites. The results are interpreted in terms of multiple attentional deficits in schizophrenics that are indicative of a failure in the planning and execution of selective listening strategies. Such a failure may result from a dysfunction in the prefrontal regions of the brain.

Adult↗
PubMed1990

Do joint receptors modulate the motoneuron excitability?

The purpose of this study was to test the effect of joint receptor afferent discharge, during rest and during small excursion movement on kinesthetic sensation and on the excitability of alpha-motoneurons in the ankle joint in normal subjects. Movement kinesthesia was tested using a specially designed test that measured the delay time between the actual and the perceived movement during slow 5 degrees/sec), passive, 20 degrees movement excursion. These data were correlated to a second kinesthetic test using a visual analog scale in which the subject compared movements of the joint being tested and the contralateral control limb joint. The excitability of alpha-motoneurons was tested using soleus H-M recruitment curve with incremented electrical stimuli to the posterior tibial nerve at the back of the knee joint. The H-reflex recovery curve was also tested using double-identical stimuli of increasing interstimulus intervals. Joint receptors were desensitized by iontophoretic application of 3 cc. of 2% xylocaine using 5 mAmp direct current for 30 min, and movement kinesthesia and H-reflexes were tested over time up to 30 min after termination of iontophoresis. Movement kinesthesia was significantly decreased (p less than 0.05) following anesthesia, and the decrease lasted during the time of the experiment. No statistically significant changes were recorded in the H-M recruitment or H-reflex recovery curves. These results indicate that joint receptor afferents may lack the spontaneous activity recorded in other receptors, such as the skin and muscles, and do not provide position sensation at the ankle joint during rest. These results also indicate that joint receptor afferents may inform the central nervous system about movement sensation in the middle range, but this information has minimal effect on the excitability of the motoneurons as measured by H-reflexes.

Adult↗
PubMed1988

Somatosensory evoked potential activity: a measure of interhemispheric transfer in schizophrenia?

Jones and Miller (1981) reported that schizophrenics could be distinguished from healthy controls by latency differences in their ipsilateral and contralateral somatosensory evoked potentials (SEPs), considered a measure of corpus callosum conduction time. Subsequent replication studies failed to follow the method of the original study. The present study represents a precise replication. An additional control for contamination of SEPs by an auditory stimulus generated by the vibrotactile stimulus was used. Ipsilateral SEP activity was identified but poor definition of a positive peak in the range of interest prevented measurement of peak latency. Evidence was advanced to suggest that such ipsilateral potentials result from activity at the vertex. It was concluded that this method is inappropriate for the investigation of interhemispheric transmission.

Adult↗
PubMed1988

Predictors of one-year developmental status in low birth weight infants.

The purpose of the present study was to describe the relations among various perinatal, environmental, and demographic measures in a sample of low birth weight infants and to relate those measures to 1-year developmental status. Perinatal variables included birth weight, gestational age, Apgar scores, and summary measures of respiratory distress and morbidity. Home visits provided ratings of the infants' environment at 7 and 12 months corrected age. The Bayley Scales of Infant Development were given at the 12-month home visit. A principal components factor analysis revealed four factors. The first factor was labeled an immaturity-illness factor, since it was primarily composed of gestational age, birth weight, and the respiratory distress and morbidity summary scores. Ratings of the infant's home environment loaded on the second factor, the demographic variables on the third factor, and the 1- and 5-minute Apgar scores comprised the fourth factor. The four factor scores together with the number of delays on the Denver Developmental Screening Test, given at 7 months corrected age, were entered as independent variables in four multiple regression analyses with the corrected and uncorrected mental development index index (MDI) and psychomotor development index (PDI) Bayley scores as the dependent variables. These regression analyses indicated that 1-year developmental status is a reflection of the infant's immaturity and neonatal morbidity, the quality of his or her home environment, and freedom from sensorimotor delays.

Child Development↗
PubMed1986

Special educational needs of the physically disabled child and adolescent.

Needs of the physically disabled student are reviewed in regard to the components of handicap and the importance of orienting teachers to diminish negative attitudes. The need for modifications of the classroom environment and conventional educational practices and equipment is described. Strategies which allow the student to bypass the disability, often by allowing technological advances to substitute for the consequences of anatomic or physiologic impairment, and the importance of ongoing dialogue between student, parents, and both rehabilitation and educational professionals are stressed.

Adolescent↗
PubMed1985

Drug and alcohol use by disabled and nondisabled persons: a comparative study.

The study is an initial attempt to provide comparative alcohol and drug use data on disabled and nondisabled persons. The lack of useful information on disabled persons is described in the literature review. Sixty-six disabled students and 115 nondisabled students returned questionnaires which examined their alcohol and drug use. The two groups were compared using tests of significance. The data provided in this report tend to confirm the notion that the disabled and nondisabled students use alcohol and drugs in similar ways. Caution is urged against generalization, and the need for additional studies is emphasized.

Adolescent↗
PubMed1984

Head injuries related to the use of baby walkers.

To determine what proportion of head injuries in children under 24 months of age who presented to an emergency department were related to the use of baby walkers, we reviewed the charts of 52 such children. Walkers were involved in 42% of the head injuries in the children under 12 months of age and in none of those in the children aged 12 to 24 months. All walker-related injuries, including skull fractures in three children, involved stairs (p less than 0.001). Questionnaires were also sent to all families with children aged 3 to 18 months attending a private pediatric practice to determine the prevalence of falls involving baby walkers among these children and the factors associated with such falls. Of the 152 responding families 82% reported using or having used a walker. Thirty-six percent of the families reported that their child had a fall while in a walker, with 8.8% of the falls resulting in contact with a doctor. Walker-related falls were directly associated with time spent in the walker (p less than 0.001) and with a previous fall from the walker by an older sibling (p less than 0.03). Since there is no demonstrated benefit of walkers, their use should not be encouraged, and parents should be advised of their potential danger.

Craniocerebral Trauma↗