PubMed Health⌕ Search

Biomedical subjects

D G Byrne

Publications and source records attributed to D G Byrne.

At least 19 recordsLinked to original sources
PubMed2006

Profiles of adolescent stress: the development of the adolescent stress questionnaire (ASQ).

The importance of stress in the understanding of adolescent health and well-being is widely documented. The measurement of adolescent stress has however been subjected to sufficient methodological and conceptual criticism in recent times to warrant a concerted re-evaluation of the exercise. This study sought information on the nature of adolescent stressors, building on a previous instrument developed by the first author to ask adolescents themselves to inform the development of a pool of new items reflecting stressor experience and to advise on the wording of these items to comprehensively assess that experience. This pool of items was then administered as a self-reported questionnaire to a large sample of school-age adolescents (N>1000) together with a scale to assess the intensity of distress arising from stressor occurrence. Principal components analysis of the questionnaire yielded 10 internally reliable dimensions of adolescent stress, the nature of which were consistent with the available literature on adolescent stressor experience. Scales constructed from this PCA related positively to measures of anxiety and depression, and negatively to a measure of self-esteem, suggesting that they were valid measures of adolescent stress. Test-retest reliability was good for all scales. The resultant Adolescent Stress Questionnaire (ASQ) is therefore suggested to have potential for the measurement of adolescent stress in both research and clinical contexts.

Achievement↗
PubMed2006

A cusp catastrophe model analysis of changes in adolescent substance use: assessment of behavioural intention as a bifurcation variable.

Behavioural intention was advanced as an alternative bifurcation variable to peer pressure in the context of a cusp catastrophe model of changes in adolescent substance use (Clair, 1998; Byrne, Mazanov & Gregson, 2001). Three sets of models were tested using data from a 12 month longitudinal study of adolescent smoking in Australia: the first with peer pressure only as the bifurcation term, the second with behavioural intention only and the third with both. In isolation both bifurcation variables performed similarly (adjusted-R2 and beta). In the third model, peer pressure edged out behavioural intention as an indicator of catastrophic change. Post hoc analysis revealed the polynomial and simple terms of initial conditions were more important than the bifurcation variable to explain change in smoking behaviour. This provoked a call for more work on finding an appropriately complex (non-straight line), theoretically justifiable mathematical model of adolescent substance use. Overall, behavioural intention was considered equivalent to peer pressure as a bifurcation variable although further research is needed to confirm this result.

Adolescent↗
PubMed2003

Adolescent stress and future smoking behaviour: a prospective investigation.

OBJECTIVE: Adolescent stress has been retrospectively associated with various measures of smoking behaviour in school-aged samples. The present study sought to extend this to a prospective investigation in order to examine the possibly formative influences of stress on the onset of smoking in adolescents. METHOD: A 12-month follow-up study related sources and degree of adolescent stress measured at study commencement with the onset of smoking behaviour 12 months later in a large cohort of adolescents attending Australian secondary schools. RESULTS: Adolescent stress was only weakly related to smoking onset in adolescent males and even this could possibly be explained by other factors. In adolescent girls, however, prospective associations were stronger and more broadly represented across the various domains of adolescent stress, suggesting that stress may exert a formative influence on smoking onset for girls. CONCLUSION: Management strategies for adolescent stress may be an affective target for smoking prevention programs among adolescent girls.

Adolescent↗
PubMed2002

A comparison of predictors of the adolescent intention to smoke with adolescent current smoking using discriminant function analysis.

OBJECTIVES: This paper explores one possible operationalization of smoking intention to assist development of adolescent smoking intervention programmes. Such programmes usually focus on predictors of current smoking, ignoring predictors of intentions to smoke, or how intentions relate to actual future smoking. DESIGN AND METHODS: Respondents took part in two stages of a repeated measures national survey on Australian adolescent smoking behaviour (12-month interval between administrations). A total of N=1419 adolescents provided matched data, measuring personal smoking habits, intentions of smoking behaviour, stress (seven subscales), self-esteem and response to the General Health Questionnaire (GHQ-12). RESULTS: A comparison of discriminant function predictors showed similarity between the current smoking and intention to smoke, with only one predictor differing between the functions. Non-smokers were more behaviourally consistent with their stated non-smoking intention over 12 months (i.e. remain non-smokers) than smokers (i.e. intention seemed unrelated to actual behaviour). CONCLUSIONS: While the predictors give no general indication of whether the processes behind the intention to smoke differ from current smoking, the intention to smoke may be a better focus for intervention with smokers given the apparent inconsistency with stated intention. Intervention for non-smokers may be usefully focused on maintaining non-smoking rather than preventing smoking.

Journal Article↗
PubMed1995

PRO_LIGAND: an approach to de novo molecular design. 6. Flexible fitting in the design of peptides.

This paper describes the further development of the functionality of our in-house de novo design program, PRO_LIGAND. In particular, attention is focused on the implementation and validation of the 'direct tweak' method for the construction of conformationally flexible molecules, such as peptides, from molecular fragments. This flexible fitting method is compared to the original method based on libraries of prestored conformations for each fragment. It is shown that the directed tweak method produces results of comparable quality, with significant time savings. By removing the need to generate a set of representative conformers for any new library fragment, the flexible fitting method increases the speed and simplicity with which new fragments can be included in a fragment library and also reduces the disk space required for library storage. A further improvement to the molecular construction process within PRO_LIGAND is the inclusion of a constrained minimisation procedure which relaxes fragments onto the design model and can be used to reject highly strained structures during the structure generation phase. This relaxation is shown to be very useful in simple test cases, but restricts diversity for more realistic examples. The advantages and disadvantages of these additions to the PRO_LIGAND methodology are illustrated by three examples: similar design to an alpha helix region of dihydrofolate reductase, complementary design to the active site of HIV-1 protease and similar design to an epitope region of lysozyme.

Amino Acids↗
PubMed1995

Personality, stress and the decision to commence cigarette smoking in adolescence.

Adolescent cigarette smoking is an increasing health risk behaviour in many societies. The reasons why adolescents commence smoking are patently complex, though it has been suggested that young people take up this behaviour as a means of stress reduction during the difficult and challenging time of adolescence. This paper reports data which suggests that adolescent stress, broadly defined, does indeed relate to the decision to commence smoking by young people. Moreover, though the personality attribute of neuroticism is independently associated with this decision, it does not mediate the association between stress and smoking onset. The implications of these data for adolescent smoking prevention programs are discussed.

Adolescent↗
PubMed1995

Type A behaviour in the Australian working population.

The Type A behaviour pattern (TABP) has been widely researched in Australian studies and, in view of its increasing prominence beyond its original association with risk of coronary heart disease, is likely to be as widely researched in this country well into the future. The Jenkins Activity Survey (JAS), being the most comprehensive self-report instrument used to assess the TABP, appears to be the instrument of choice for the measurement of the TABP in Australia, particularly in epidemiological studies where large samples are involved, or in other studies where either the interview method is impractical or the researchers are untrained in its application. This paper presents normative data on the use of the JAS in the Australian context, derived from a series of empirical studies undertaken by the authors over the past decade. Sociodemographic correlates of these data are presented, and refinements of the JAS for future use are suggested.

Adult↗
PubMed1993

The effect of exercise on depression, anxiety and other mood states: a review.

This paper addresses the current literature related to investigations of the link between exercise treatments and depression, anxiety and other mood states. Results from these investigations are supportive of the anti-depressant, anti-anxiety and mood enhancing effects of exercise programs. There were considered to be, however, a number of potential methodological problems in many of the research studies; the nature of these were considered. Finally, some possible directions for future research are outlined.

Affect↗
PubMed1989

Occupation, type A behavior and self-reported angina pectoris.

The utility of the Type A Behavior Pattern (TABP) as an explanatory concept in psychosomatic medicine has recently been challenged by the appearance of data casting doubt on associations between the TABP and coronary disease. The present study examined an interactive view of the relationship between the TABP and self-reported angina pectoris by suggesting that the TABP exerts a pathogenic influence only under certain occupational conditions. The data gave broad support to this view, and while the results are as yet preliminary, they point to a means of extending the usefulness of the TABP as a variable in epidemiological studies of cardiovascular disease.

Achievement↗
PubMed1989

Type A behaviour and the authoritarian personality.

The demonstration of modest statistical associations between measures of the Type A behaviour pattern (TABP) and some measures of authoritarianism has given rise to a view that the TABP represents little more than an attempt by some individuals to exercise the personality attribute of dominance. The present study examined this view with regard to a wide selection of measures of the authoritarian personality and found that measures of the TABP related only to measures of authoritarianism reflecting authoritarian behaviours. While such correlations indicate a facet of the TABP resembles the attribute of dominance, they do not amount to conceptual equivalence of the TABP and authoritarianism. The conceptual complexity of the TABP demands a more multidimensional view of this explanatory notion in medical psychology.

Adult↗
PubMed1986

Type A behaviour and the experience of affective discomfort.

Early views of the Type A behaviour pattern (TABP) sought to disengage it from either neuroticism or emotional distress. Recent evidence challenging these views has, however, recommended a reevaluation of the area. Data arising from the present study indicate the TABP to be statistically related to measures of both neuroticism and emotional distress, though whether this association extends to a conceptional similarity, particularly with the former, is a matter for further discussion.

Adaptation, Psychological↗
PubMed1986

The type A behaviour pattern as a precursor to stressful life-events: a confluence of coronary risks.

Both the Type A Behaviour Pattern (TABP) and the presence of stressful life-events have been independently established as precursors to the onset of coronary heart disease (CHD). The thematic character of the TABP suggests, however, that the two phenomena might be linked, to the extent that features of the TABP may place an individual in social, occupational and personal circumstances which enhance the probability of encountering stressful life-events. Evidence from survivors of clinical CHD gives some support to this idea. The present study extends the hypothesis to a large sample of healthy males, screened for CHD risk factors. These results, too, support the idea that the TABP and encounters with stressful life-events are not entirely independent phenomena. Associations between the TABP and a range of measures of life-events were most evident in the occupational aspects of the latter, though not exclusively so. The data do point to the need, in future epidemiological studies of CHD risk, to treat the TABP and stressful life-events as related measures of CHD risk.

Adult↗
PubMed1984

Personal assessments of life-event stress and the near future onset of psychological symptoms.

This report presents data on prospective associations of life-event measures with psychological symptoms. Two issues in particular are addressed, the one relating to the causal influence of life-events on symptom onset, and the other to the role of personal interpretations of life-event impact in this association. The latter issue derives from a consideration of the cognitive view of stress. Prospective associations did, indeed, emerge and were strongest where the individual was permitted to personally assess the impact of encountered life-events. Temporal patterns of association varied with the kinds of symptoms (anxiety of depression) used as the dependent variable.

Adjustment Disorders↗
PubMed1983

Personal determinants of life event stress and myocardial infarction.

Data was drawn from several studies undertaken by the author to examine the idea that life events associated with myocardial infarction are to some degree influenced by personal factors characteristic of the individual. It was found that persons with the type A behaviour pattern were more likely to encounter life events than others, and patients with myocardial infarction were more likely than others to interpret encountered life events in an emotionally adverse way. These data were discussed in the light of research strategies linking life events with cardiovascular disease.

Adaptation, Psychological↗
PubMed1982

Hypertension: comparison of drug and non-drug treatments.

Thirty-seven reports of the treatment of hypertension by non-pharmacological means were compared with the results of treatment by standard drug regimens. Treatment by drugs produced the greatest lowering of blood pressure. Treatment by weight reduction, yoga, and muscle relaxation each produced smaller, but appreciable, changes in blood pressure biofeedback, and salt restriction were inferior to those of the other regimens and were not significantly different to the effects of placebo treatment. Large comparative trials of pharmacological and non-pharmacological treatments are needed before definite conclusions can be made.

Biofeedback, Psychology↗