Now showing 1 - 10 of 21
  • Publication
    Comparing different EEG connectivity methods in young males with ASD
    Although EEG connectivity data are often used to build models of the association between overt behavioural signs of Autism Spectrum Disorder (ASD) and underlying brain connectivity indices, use of a large number of possible connectivity methods across studies has produced a fairly inconsistent set of results regarding this association. To explore the level of agreement between results from five commonly-used EEG connectivity models (i.e., Coherence, Weighted Phased Lag Index- Debiased, Phase Locking Value, Phase Slope Index, Granger Causality), a sample of 41 young males with ASD provided EEG data under eyes-opened and eyes-closed conditions. There were relatively few statistically significant and/or meaningful correlations between the results obtained from the five connectivity methods, arguing for a re-estimation of the methodology used in such studies so that specific connectivity methods may be matched to particular research questions regarding the links between neural connectivity and overt behaviour within this population.
  • Publication
    Sensory Features and Bi-directional EEG Connectivity in Young Autistic Males

    Several lines of research suggest that autism is a neurological phenomenon, but the precise associations between neurological activity and the key diagnostic symptoms of autism are yet to be completely clarified. This study examined EEG connectivity and Sensory Features (SF) in a sample of young autistic males by examining bi-directional neural connectivity between separate brain regions as the key potential correlate of SF. Forty male autistic participants aged between 6 and 17 years, with an IQ of at least 70, underwent EEG measurements of their Frontal, Occipital and Temporal region responses to low-, medium-, and high-intensity audiovisual stimulus conditions. EEG connectivity data were analysed via Granger Causality. SF was measured via parent responses about their sons on the Child Sensory Profile (2nd ed.) (CSP-2). There were significant (p < .05) correlations between right hemisphere Frontal and Temporal connectivity and CSP-2 dominant scores, largely due to lower Temporal-to-Frontal than Frontal-to-Temporal connectivity. There were no significant correlations between general CSP-2 scores and EEG connectivity data collected during audiovisual stimuli. These results confirm and extend previous findings by adding bi-directional connectivity as an index of brain activity to other studies that used only uni-directional connectivity data when measuring SF. Although there may be a discrepancy between the kinds of information collected via instruments such as the CSP-2 and actual brain electrical connectivity across major regions, these results hold implications for the use of brain-training interventions with autistic boys.

  • Publication
    Girls' cortisol concentrations, mothers' anxiety, and self- versus parent-ratings of autistic girls' anxiety

    Background: Autistic girls’ change in salivary cortisol concentrations from morning to afternoon were compared with their parents’ own anxiety states as potential correlates of the autistic girls’ self-ratings of their anxiety and those given by their parents about their daughters’ anxiety.

    Methods: Thirty-three autistic girls (6 yr to 10 yr, M = 8.21 yr, SD = 1.29 yr) and 19 autistic adolescent females (11 yr to 15 yr, M = 12.74 yr, SD = 1.52 yr) completed anxiety inventories about themselves and provided saliva samples in the morning and afternoon. Their mothers also rated their daughters’ anxiety and their own anxiety.

    Results: There were no significant differences between mothers’ and daughters’ ratings of the latter’s GAD. The autistic girls’ self-ratings of their anxiety were more strongly influenced by their mothers’ anxiety in the younger girls, but more responsive to their own chronic stress state (i.e., cortisol) in the adolescent girls.

    Conclusions: Mothers’ evaluations of their autistic daughters’ anxiety appear to be strongly influenced by their own anxiety. There was also some indication that autistic girls may disguise their anxiety.

  • Publication
    The use of salivary cortisol as an index of chronic stress that correlates with depression in prostate cancer patients
    Cortisol is a neurohormone released after a cascade response to stressors that begins in the hypothalamus, moves to the pituitary gland, and then to the adrenals, which secrete cortisol into the bloodstream as the final stage in this cascade. Cortisol affects many physiological functions, including vital anti‐inflammatory and immunosuppressive actions, as well as metabolism and homeostasis. Consequently, a basal concentration of cortisol is required at all times but may become immediately elevated in response to physical or mental stressors, usually returning to basal levels later. Underneath this immediate response to stressors, cortisol displays a diurnal variation so that concentrations are at their apex about 45 min after waking in the morning and decrease to their nadir in the early evening, a process referred to as the diurnal fluctuation in cortisol. However, this variation may become dysregulated by chronic stress and instead become consistently elevated, resulting in hypercortisolemia, which is characterized by an ongoing elevated concentration of cortisol in the bloodstream that is associated with pain, fatigue, increased risk of heart disease, and the symptoms of anxiety, muscle wastage, and hyperglycemia.
  • Publication
    Using Electroencephalography to Measure the Effects of Sensory Features upon Functional and Effective Connectivity in Children and Adolescents with Autism Spectrum Disorder

    Autism Spectrum Disorder (ASD) is a neurodevelopmental condition, characterised by impairments in social communication and the presence of restricted and repetitive behaviours, activities, or interests. ‘Sensory Features’ (SF) are a key symptom of ASD, and affect 90-95% of individuals with ASD, manifesting as atypical behavioural, neurological, and self-regulatory responses to sensory stimuli in the environment. Although the overt behavioural characteristics of SF in people with ASD have been extensively investigated, internal neurophysiological processes of SF in the ASD population have been minimally explored. One method of identifying these internal neurophysiological processes associated with SF is by using electroencephalography (EEG) to measure the brain’s electrical activity, and the ways that regions of the brain communicate or ‘connect’ with each other. There is a paucity of research investigating the direct relationship between SF and brain neural connectivity in children and adolescents with ASD, and this issue was made the focus of this research. Therefore, the current study aimed to investigate the relationship between SF in the ASD population and neural connectivity via (i) analyses of five different types of EEG connectivity measurements based on resting EEG data during eyes-closed and eyes-opened conditions, and (ii) analysis of Granger Causality on naturalistic audiovisual low-, medium-, and high-intensity stimulus conditions. The current study also aimed to investigate whether there was a relationship between age and Granger Causality connectivity indices in the ASD sample.

    Forty-one male participants aged between 6 and 17 years, with an IQ of at least 70 and who were diagnosed with ASD took part in the current study. Connectivity analysis (using five methods: Coherence, Weighted Phase Lag Index-Debiased, Phase Locking Value, Granger Causality, and Phase Slope Index) and subsequent statistical analyses (using Pearson product moment and Spearman correlations, MANOVA, and paired samples t-tests) were conducted on EEG data from these participants.

    Results indicated (i) minimal agreement between functional and effective connectivity for eyes-closed and eyes-opened conditions, (ii) significant (p < .05) deficits in connectivity between right hemisphere frontal and temporal brain regions, and a lack of significant correlations between this connectivity and Sensory Quadrant data collected on the Child Sensory Profile ( 2nded.) for audiovisual stimuli, (iii) no significant differences in connectivity between frontal and occipital regions for all resting and stimulus conditions, and (iv) no significant correlations between age and neural connectivity in frontal, temporal, and occipital regions in response to audiovisual stimuli.

    The results from this research add to the current literature and provide more evidence of atypical neuronal communication, especially between frontal and temporal regions, in regards to SF in male children and adolescents with ASD. Further research using a consistent connectivity method to analyse the associations between EEG connectivity and naturalistic experimental stimuli may provide more meaningful insights and suggestions for neurophysiological interventions to reduce the adverse effects of SF in individuals with ASD.

  • Publication
    Comparing a genetic and a psychological factor as correlates of anxiety, depression, and chronic stress in men with prostate cancer
    Purpose: Some prostate cancer (PCa) patients become clinically anxious or depressed after diagnosis and treatment. Some also show the physiological signs of chronic stress. However, there are currently no data describing how these particular patients might be identified at intake. This study tested the individual and combined predictive power of a psychological factor and a genetic factor as potential predictors of anxiety, depression, and chronic stress in a sample of PCa patients. Methods: Ninety-five PCa patients completed psychological inventories for anxiety, depression, and psychological resilience (PR) and also gave a saliva sample for cortisol and a mouthwash sample for genetic testing for the presence of the BDNF Val66Met polymorphism. Results: High PR patients had significantly lower anxiety and depression than low PR patients, but showed no significant differences in their salivary cortisol. Carriers of the Met allele of the BDNF Val66Met polymorphism had significantly higher salivary cortisol concentrations than patients who did not carry this allele. Conclusions: Each of these two factors may provide valuable information regarding the vulnerability of PCa patients to anxiety, depression, or chronic stress. Suggestions are made for their inclusion in clinical settings.
  • Publication
    Does the cortisol: CRP ratio inform the measurement of individual burden of illness for depression in community samples?

    Background: Individual Burden of Illness for Depression (IBI-D) represents a method for assessing the degree to which depressive symptomatology reduces functioning. Although the IBI-D has been shown to provide more information than measures of depressive symptomatology alone, previous studies have relied upon participant self-reports, and have not included an objective measure of physiological functioning. Such an index might add to the validity and informational value of IBI-D data.

    Methods: Responses to scales measuring depressive symptoms, functional impairment due to mental and physical health, and saliva samples were collected from 111 community volunteers from rural Australia. Saliva was assayed for cortisol and C-Reactive Protein concentrations, and the ratio of these was used as an indicator of the balance between the Hypothalamic-Pituitary-Adrenal axis and the inflammatory response from the immune system.

    Results: Principal Components Analysis (PCA) produced two- and three-factor solutions from the psychological and biological data, and were used to form weighted models of two IBI-D equations. Stepwise regression analysis indicated that the addition of the biological index to the second IBI-D made a significant extra contribution to variance in depression score.

    Limitations: No longitudinal data were collected, participants were from a single geo-cultural region, and were self-selecting. Clinician interviews might augment participant self-reports.

    Conclusions: Valid assessment of the self-reported symptoms of depression provides one aspect of diagnostic information, but the addition of biological information can further inform clinicians and researchers about the effect that these symptoms have upon individual patient functioning.

  • Publication
    Associations between stress and depression symptom profiles vary according to serotonin transporter polymorphism in rural Australians
    (Dove Medical Press Ltd, 2018-08-10) ; ; ;
    Jesulola, Emmanuel
    ;
    Purpose: Depression remains difficult to treat in all cases, and further investigation of the role of genetic and environmental factors may be valuable. This study was designed to investigate the association between the short (s) versus non-short (non-s) 5HTTLPR variants, presence of childhood stressors and recent life stressors, and depression, and to do so at two levels that would expose the associations between total depression scores and also individual depression items. Materials and methods: Two hundred and forty-nine volunteers from one of the Australian Electoral Office electorates covering a large rural land area completed a series of questionnaires about childhood and recent life stress and depression, and provided a buccal cell sample for genotyping the 5-HTTLPR polymorphism into s versus non-s carriers. Results: Although there were no significant differences in the depression scores of the s-carriers versus the non-s carriers, each subtype of the 5-HTTLPR polymorphism showed different patterns of association between childhood stress and depression symptoms, and between recent life stress and depression symptoms. Conclusion: Individualization of therapy for depression may be achieved through consideration of the specific associations that patients exhibit between life stress, 5-HTTLPR polymorphism, and depression symptomatology.
  • Publication
    A Brief Report on the 2.4-Year Test-Retest Agreement of Morning Cortisol and Anxiety in Boys with Autism Spectrum Disorder
    Children with Autism Spectrum Disorder (ASD) also often suffer from elevated stress and anxiety. These states can be measured via reports of behaviour (from self or others) or from physiological measures of stress, including the symptoms of Generalised Anxiety Disorder (GAD) and salivary cortisol, respectively. The use of these measures assumes a degree of reliability over time so that data from a specific period may be generalised to other periods. To measure the test-retest reliability of salivary cortisol and self-ratings of GAD in 27 high-functioning boys with ASD (M age = 12.1 yr., SD = 2.8 yr), samples were collected a mean of 2.4 yr. (SD = 0.5 yr) apart and analysed to test for the presence of a significant correlation within each variable over time. Results indicated that, although the concentrations of salivary cortisol increased over the period of the study, there was a significant correlation between the two measures of cortisol. GAD scores also showed a significant correlation over the period of the study. These findings suggest that both GAD and salivary cortisol data collected from boys with ASD may be reasonably inferred to represent fairly stable phenomena over time in research and clinical settings.
  • Publication
    Does psychological resilience buffer against the link between the 5-HTTLPR polymorphism and depression following stress?
    The comparative strength of the 5-HTTLPR polymorphism as a 'predictor' of depression after major stress, versus the 'protective' effect of psychological resilience (PR) against depression after major stress, was tested in a homogeneous sample of older men who had all received a diagnosis and treatment for prostate cancer. Results supported the association between PR and lower depression after stress, but did not support the association between the 5-HTTLPR and elevated depression after stress. Examination of PR at scale, factor, and item level identified the specific PR-related behaviour that was the most powerful predictor of low depression. These data suggest that the carriage of the short form of the 5-HTTLPR may negate the protective effect of PR against depression in these men, or that PR may nullify the depression vulnerability of this form of the 5-HTTLPR. These findings may explain some of the 'null' findings regarding the link between the 5-HTTLPR and depression in the wider literature by arguing for an interaction between these two factors in the association between major stress and depression.