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Biomedical subjects

E F Walker

Publications and source records attributed to E F Walker.

At least 19 recordsLinked to original sources
PubMed1999

Motor dysfunction in schizotypal personality disorder.

Past research has revealed that schizophrenia is associated with voluntary movement abnormalities, as well as higher rates of involuntary movements. On instrumental motor tasks, patients manifest reduced motor stability, excessive force and more contralateral motor overflow (movement in the non-responding hand). In the present study, an instrumental motor task (manual response forced-choice task) was administered to a group of adults with schizotypal personality disorder (SPD) in order to determine whether they show motor deficits similar to those observed in schizophrenia. As predicted, the schizotypal subjects were excessive and more variable in motor force, compared to healthy controls and other personality-disordered subjects. Additionally, the force and variability of the motor responses were positively correlated with ratings of both positive and negative SPD symptoms. Finally, motor overflow and negative symptoms were associated with higher salivary cortisol levels. The pattern of findings is consistent with previous reports linking motor abnormalities and heightened cortisol with schizotypal personality disorder.

Adult↗
PubMed1999

Developmental neuropathology and the precursors of schizophrenia.

Changes in the manifestation of vulnerability to schizophrenia across the lifespan may hold important clues about aetiology. They may also illustrate some general principles about the nature of neurodevelopmental processes. Within the framework of a neural diathesis-stress model, we review findings on the precursors of schizophrenia and schizotypal personality disorder. The findings suggest that there are critical developmental periods for the manifestation of dysfunction and that, within certain domains of behaviour, there is a temporal disjunction between the onset of the neuropathology and its expression. It also appears that the diathesis for schizophrenia involves polymorphic behavioural expression, such that it can be manifested in multiple domains - motoric, cognitive and socio-emotional. Taken together, the data on the longitudinal course of schizophrenia indicate that the expression of the diathesis is moderated by central nervous system maturational processes. One putative moderating system, the hypothalamic-pituitary-adrenal (HPA) axis, is discussed, and implications for preventive intervention are explored.

Age Factors↗
PubMed1997

Neuromotor functioning and behavior problems in children at risk for psychopathology.

Previous studies have found that early neuromotor deficits may be a precursor of later psychopathology. The present study examined the relationship between neuromotor dysfunction and behavioral deviance in children characterized by a variety of risk factors (parental schizophrenia, parental psychiatric disorder other than schizophrenia, and parental maltreatment). The sample consisted of 108 children (average age 9.75 years) who were assessed twice, approximately 1 year apart. It was was found that maltreated children had poorer neuromotor functioning and more behavior problems than children who were not maltreated, regardless of parental psychiatric status. The results also indicated that the relationship between neuromotor functioning and problem behaviors varied as a function of parental psychiatric status. These findings suggest that, although the effects of maltreatment are generalized and pervasive, there are distinctive relationships between neuromotor functioning and behavioral deviance depending on the nature of the risk factors a child has been exposed to.

Adolescent↗
PubMed1997

Schizophrenia: a neural diathesis-stress model.

There is a substantive literature on the behavioral effects of psychosocial stressors on schizophrenia. More recently, research has been conducted on neurohormonal indicators of stress responsivity, particularly cortisol release resulting from activation of the hypothalamic-pituitary-adrenal (HPA) axis. This article integrates the psychosocial and biological literatures on stress in schizophrenia, and it offers specific hypotheses about the neural mechanisms involved in the effects of stressors on the diathesis. Both the behavioral and biological data indicate that stress worsens symptoms and that the diathesis is associated with a heightened response to stressors. A neural mechanism for these phenomena is suggested by the augmenting effect of the HPA axis on dopamine (DA) synthesis and receptors. Assuming the diathesis for schizophrenia involves an abnormality in DA receptors, it is proposed that the HPA axis acts as a potentiating system by means of its effects on DA. At the same time, DA receptor abnormality and hippocampal damage render the patient hypersensitive to stress. This neural diathesis-stress model is consistent with findings on prenatal factors and brain abnormalities in schizophrenia, and it provides a framework for explaining some key features of the developmental course and clinical presentation.

Disease Susceptibility↗
PubMed1996

Childhood behavioral characteristics and adult brain morphology in schizophrenia.

It is well established that many schizophrenia patients manifest behavioral dysfunction long before the onset of clinical symptoms of illness. Some show signs of motor and socioemotional deficit as early as infancy. The present study examines the relations among childhood neuromotor, affective and behavior characteristics, and the association of these factors with adult brain morphology (MRI) in schizophrenia patients. Data on neuromotor functions and negative affect were obtained from coding of childhood films. Parents of patients provided information about six dimensions of childhood behavior problems. Analyses of data from patients and healthy siblings revealed that childhood neuromotor abnormalities and negative affect were associated with some of the behavioral dimensions. Among the patients, early childhood neuromotor deficits and negative affect were linked with greater ventricular enlargement in adulthood. The ratings of the behavior problem dimensions showed a complex relation with adult brain morphology, suggesting that externalized problems are linked with more abnormalities (smaller brain volume and larger ventricles), whereas internalized problems are associated with less abnormality. The findings are discussed in light of their implications for the developmental origins of brain abnormalities in schizophrenia.

Adolescent↗
PubMed1996

Sex differences in neuropsychological functioning among schizophrenic patients.

OBJECTIVE: The view of schizophrenic men as having poorer premorbid development, earlier age at onset, and worse outcome than schizophrenic women predicts greater neuropsychological impairment in the former than the latter. The authors examined in detail neuropsychological functioning in a large group of schizophrenic patients and a healthy comparison group. METHOD: Neuropsychological functioning in 132 male and 63 female patients with schizophrenia or schizoaffective disorder was extensively studied and compared with that of 99 (40 male, 59 female) healthy individuals. RESULTS: As expected, the schizophrenic patients as a group were pervasively and significantly more impaired than the comparison group. Within schizophrenia, in contrast to the prediction, women performed significantly more poorly than men in verbal memory, spatial memory, and visual processing. Female schizophrenic patients also had significantly poorer right than left hemisphere performance, whereas male schizophrenic patients had identical scores for right and left hemisphere impairment. CONCLUSIONS: The findings are consistent with the hypothesis that schizophrenia among women may be partially understood as a right hemisphere dysfunction. Sampling, diagnostic, and epidemiologic factors may have affected the results.

Adult↗
PubMed1995

Childhood behavioral precursors of adult symptom dimensions in schizophrenia.

The present investigation tested the hypothesis that childhood behavioral problems are differentially associated with clinical symptoms in adult-onset schizophrenia. Parents of 29 schizophrenic patients completed questionnaires concerning (1) the childhood behaviors of all their offspring from birth through 15 years of age, and (2) the symptomatology of their schizophrenic offspring. The childhood behavior scale was a modified version of Achenbach's Child Behavior Checklist (1991). Scores were derived for six childhood behavior problem factors: Withdrawal, Anxiety/Depression, Social Problems, Thought Problems, Attention Problems, and Aggression/Delinquency. Ratings of symptoms were based on parental versions of Andreasen's Scale for the Assessment of Positive Symptoms (SAPS; 1983) and Scale for the Assessment of Negative Symptoms (SANS; 1981). Symptomatology scores were computed from the SANS and SAPS following Malla et al.'s (1993) and Liddle's (1987b) tri-dimensional concept of schizophrenia: Reality Distortion, Psychomotor Poverty and Cognitive Disorganization. Regression analyses were conducted to examine the relation between childhood behavior and adult symptomatology in the schizophrenic patients. The results indicated that the Psychomotor Poverty and Cognitive Disorganization dimensions in adult patients are positively associated with Withdrawn behavior and inversely associated with Anxious/Depressed characteristics in childhood. The results are discussed in light of the distinction between primary and secondary negative symptoms, and the three dimension concept of schizophrenia.

Adolescent↗
PubMed1995

Developmental pathways to schizophrenia: behavioral subtypes.

This study examined childhood behavior problems in schizophrenic patients and their healthy siblings. Childhood Behavior Checklist (T. Achenbach, 1991) ratings were obtained from retrospective maternal reports, for 4 age periods: birth to 4 years, 4 to 8 years, 8 to 12 years, and 12 to 16 years. The results indicated that the patients had a variety of childhood behavior problems when compared to their siblings and that the various types of problems differed in their developmental course. Cluster analysis was conducted on the childhood behavior ratings for the schizophrenic patients, and 2 subgroups emerged. Cluster I showed more pronounced behavioral problems than Cluster II, and some of these problems were apparent in early childhood and increased with age. Cluster I also demonstrated greater neuromotor abnormalities in childhood.

Adolescent↗
PubMed1994

Childhood emotional expressions, educational attainment, and age at onset of illness in schizophrenia.

This study examined the relation between preschizophrenic subjects' facial expressions of emotion in childhood home movies and two criterion variables: educational level (highest grade completed) and age at onset of illness. Earlier research suggest that premorbid affective blunting is associated with an earlier onset of illness and poorer prognosis in schizophrenia. It was, therefore, predicted that lower rates of both positive and negative facial expressions would be associated with lower levels of educational attainment and earlier age at onset of illness. The results indicated that childhood emotional expressions were not associated with educational level but were linked with age at onset. Preschizophrenic subjects who showed lower rates of negative emotion during late childhood/adolescence were younger at illness onset. Findings are discussed in light of previous reports linking affective symptoms with better prognosis in schizophrenia.

Adult↗
PubMed1994

Neuromotor precursors of schizophrenia.

Previous research suggests that in addition to being a characteristic of schizophrenia, neuromotor dysfunction also predates the onset of the syndrome. The research reported here was intended to examine further the neuromotor development of children with preschizophrenia traits. This study is part of a larger "archival-observational" project that uses childhood home movies to explore the developmental precursors of schizophrenia. Group comparisons revealed a higher rate of neuromotor abnormalities in the preschizophrenia children when compared to their healthy siblings, preaffective disorder subjects, the healthy siblings of patients with affective disorder, and subjects from families with no mental illness. The preschizophrenia subjects also showed poorer motor skills when compared to their healthy siblings and preaffective disorder subjects. When diagnostic group comparisons were made within age spans, the group differences were significant only in the first 2 years of life. Post hoc analyses also revealed that the preschizophrenia subjects' neuromotor abnormalities occurred primarily on the left side of the body. The abnormalities included choreoathetoid movements and posturing of the upper limbs, similar to the motor signs described in earlier reports on diagnosed schizophrenia patients. The findings are discussed in light of their implications for the developmental origins of schizophrenia. Limitations of the study, including problems with sample representativeness and the reliance on observational data, are also discussed.

Adolescent↗
PubMed1994

Developmentally moderated expressions of the neuropathology underlying schizophrenia.

A gradually accumulating body of literature suggests that behavioral dysfunction precedes the onset of the schizophrenic syndrome by many years. Thus, a comprehensive neurodevelopmental model of schizophrenia must encompass these early manifestations of dysfunction as well as the postmorbid period. This article draws on previous research findings as well as recently proposed neurodevelopmental models to offer some further hypotheses about the neurodevelopmental process underlying the changing life-course manifestations of the diathesis for schizophrenia. It is proposed that normal maturational events in the central nervous system moderate the behavioral expression of a congenital neuropathology that affects subcortical regions of the brain that are part of multiple neural circuits. Specifically, it is suggested that the diathesis for schizophrenia involves a functional excess of dopamine activity in the basal ganglia that serves to disrupt these circuits. Findings from empirical research suggest a modal developmental trajectory for schizophrenia in which neuromotor dysfunction is most pronounced in early childhood and late in life, whereas florid psychotic symptomatology is most pronounced in late adolescence and early adulthood. The literature on normal central nervous system development suggests that the feedback circuit linking motor cortex with subcortical structures is maximally metabolically activated, relative to other circuits, early and late in the life course. Thus, subcortical dopamine excess may be predominantly expressed in motoric symptoms during these periods. In contrast, late adolescence and early adulthood are marked by low motor cortex metabolic activity relative to other cortical regions, in particular limbic and frontal regions. In addition, hormonal changes appear to result in a maximal activation of the dopamine system during this developmental period. Thus, it is hypothesized that during this period the neural circuitry abnormality will be primarily behaviorally expressed in psychotic symptoms. Some implications of the model for the study of movement abnormalities and psychotic symptoms are discussed.

Adolescent↗
PubMed1993

Sampling biases in studies of gender and schizophrenia.

Gender differences in schizophrenia are of great interest to researchers, and some have recently concluded that female patients suffer from a more benign form of the illness. However, the research findings do not support this conclusion consistently, and some reports suggest greater impairment in female patients. In this article, we discuss the potential effects of sampling biases on the findings from studies that compare male and female patients. More specifically, we assume that females do manifest a less severe schizophrenic illness than males, and we propose that sex differences in severity thresholds for voluntary and involuntary treatment are contributing to inconsistencies in the research findings. Some other sources of sampling bias that may influence findings on gender differences are also discussed.

Bias↗
PubMed1993

Childhood precursors of schizophrenia: facial expressions of emotion.

OBJECTIVE: This study sought to determine whether affective abnormalities could be detected in home movies of children who later developed schizophrenia. METHOD: Trained observers coded facial expressions of emotion of 32 schizophrenic patients and 31 of their healthy siblings from home movies made when they were children. All of the patients met the DSM-III criteria for schizophrenia with onset in late adolescence or early adulthood. The sibling comparison subjects had no history of psychiatric illness. Nine emotions and a neutral category were rated. RESULTS: Analyses revealed significantly lower proportions of joy expressions among the total expressions of the preschizophrenic female subjects than among the same-sex healthy siblings. This difference extended from infancy through adolescence. Among the male subjects, there were inconsistent differences between diagnostic groups in expressions of joy across age levels. However, both the preschizophrenic male subjects and the preschizophrenic female subjects showed greater negative affect than their same-sex comparison groups. CONCLUSIONS: These findings lend support to the assumption that vulnerability to schizophrenia may be subtly manifested in emotional behavior long before the onset of clinical symptoms.

Adolescent↗
PubMed1990

The effects of familial risk factors on social-cognitive abilities in children.

Consistent with the results of previous studies of children with depressed parents, the present investigation of social-cognitive abilities with schizophrenic parents yields no evidence of deleterious effects of parental psychopathology. Similarly, maltreatment was not associated with social-cognitive deficits. The central conclusion to be drawn from these results is that social-cognition does not mediate the effects of these risk factors on child behavior, although social-cognition may serve as a moderator.

Adolescent↗
PubMed1988

The positive/negative symptom distinction in psychoses. A replication and extension of previous findings.

The independence and internal consistency of Andreasen's positive and negative symptom scales was found to be good for schizophrenics but not for a comparison group of manic patients, supporting the assumption that the symptom distinction is diagnosis specific. Discriminant function analysis revealed that ratings of positive and negative symptoms are capable of predicting diagnostic category for the two groups with a high degree of accuracy.

Adult↗
PubMed1986

Identification and reporting of child maltreatment by Head Start personnel: attitudes and experiences.

A two-part questionnaire was administered to 143 Head Start personnel in order to determine how personal characteristics of the Head Start workers and the characteristics of the families they serve, affect the identification and reporting of child maltreatment. Of additional interest was whether some forms of maltreatment, once identified, would be more likely to be reported than other forms of maltreatment. The results support the efficacy of educational programs in child maltreatment for increasing the identification and reporting of maltreatment by workers. They also indicate that there are complex interactions between certain characteristics of the reporter (e.g., educational level) and prior training in maltreatment identification. Finally, neglect, although more frequently identified by the workers, appears to be least likely of all forms of maltreatment to be reported to official sources. Results are discussed in light of their implications for future research and practical application.

Adult↗