Journal Articles

Published Research

The following is a summary of journal publications by Associate Professor Knowles. Click on the references below for further details.

Journal Articles


Austin, D., Spolding, B., Gondalia, S., Shandley, K., Palombo, E., Knowles, S., & Walder, K. (2014). Genetic variation associated with hypersensitivity to mercury. Toxicology International, 21(3): 236–241, doi: 10.4103/0971-6580.155327.

Objectives: Very little is known about mechanisms of idiosyncratic sensitivity to the damaging effects of mercury (Hg); however, there is likely a genetic component. The aim of the present study was to search for genetic variation in genes thought to be involved in Hg metabolism and transport in a group of individuals identified as having elevated Hg sensitivity compared to a normal control group.

Materials and methods: Survivors of pink disease (PD; infantile acrodynia) are a population of clinically identifiable individuals who are Hg sensitive. In the present study, single nucleotide polymorphisms in genes thought to be involved in Hg transport and metabolism were compared across two groups: (i) PD survivors (n = 25); and (ii) age- and sex-matched healthy controls (n = 25).

Results: Analyses revealed significant differences between groups in genotype frequencies for rs662 in the gene encoding paraoxanase 1 (PON1) and rs1801131 in the gene encoding methylenetetrahydrofolate reductase (MTHFR).

Conclusions: We have identified two genetic polymorphisms associated with increased sensitivity to Hg. Genetic variation in MTHFR and PON1 significantly differentiated a group formerly diagnosed with PD (a condition of Hg hypersensitivity) with age- and gender-matched healthy controls.



Knowles, S. R., Tribbick, D., Connell, W.R., Castle, D., Salzberg, M., Kamm, M.A. (2014). Exploration of illness perceptions, coping strategies and psychological morbidity in stoma patients. Journal of Wound, Ostomy and Continence Nursing. 41(6):573-80.

Purpose: We employed the Common Sense Model (CSM) of illness perceptions to examine the relative contribution of illness perceptions, stoma self-efficacy, and coping strategies in explaining anxiety and depression symptoms in patients with a fecal ostomy. The CSM suggests that the consequences of illness activity, such as psychological distress, are influenced by an individual’s illness perceptions as well as what coping strategies they engage in.

Design: Descriptive, cross-sectional questionnaire-based study.

Subjects and setting: One hundred fifty adults with a stoma (54 males, and 96 females; mean age 44 years) completed an online survey.

Methods: Several instruments were used to measure study outcomes, including the Health Perceptions Questionnaire, Brief Illness Perceptions Questionnaire, Carver Brief Coping Questionnaire, Stoma Self-Efficacy Scale, and the Hospital Anxiety and Depression Scale. Participants were advised of the study through online forums containing a link to the survey. Outcome measures used in the current study are valid and reliable and have been extensively used in medically ill patients.

Results: Using structural equation modeling, the final model provided an excellent fit to the data (χ23= 16.53, P = .22, χ/N = 1.27, SRMR < 0.03, RMSEA < 0.05, GFI > 0.97, CFI > 0.99). There was a direct pathway from health status to illness perceptions months since surgery directly influenced health status, illness beliefs, and adaptive emotion-focused coping (β= .81, P < .001). Several indirect (mediating) pathways were also identified. Illness perceptions mediated the relationship between health status and stoma self-efficacy and maladaptive and adaptive emotion-focused coping. Maladaptive coping mediated the relationship between illness perceptions and depression and anxiety, and adaptive emotion-focused coping mediated the relationship between illness perception and depression. The final model provided support for the CSM, in that illness perceptions were directly related to illness status, and that both illness perceptions and coping strategies directly influenced anxiety and depression. More specifically, maladaptive coping style (eg, ignore problems) exacerbated depression and anxiety symptoms, while self-efficacy and emotion-focused coping style (eg, seek advice) ameliorate depression, but not anxiety. Months since surgery was associated with improved health status, reduced poorer illness perceptions, and increased emotional-focused coping.

Conclusions: Illness perceptions and coping were found to mediate anxiety and depression. The results confirm that how individuals perceive their illness and what coping strategies they engage in impacts their psychological well-being. Study findings support the need for designing targeting psychological interventions based on individual illness perceptions and self-efficacy rather than exclusively focusing on coping strategies in patients with a stoma.


Dowsey, M. M., Castle, D. J., Knowles, S. R., Monshat, K., Salzberg, M. R., Choong, P. F. M. (2014). The effect of mindfulness training prior to total joint arthroplasty on post-operative pain and physical function: study protocol for a randomised controlled trial. Trials, 15:208.

Background: Osteoarthritis is a leading cause of disability in developed nations. In Australia it afflicts 16.5% of the adult population. Total joint arthroplasty is considered the treatment of choice for end stage osteoarthritis. The number of total joint arthroplasties undertaken in Australia has doubled over the last decade (more than 80,000 procedures in 2011). The incidence of pre-operative psychological distress in this group of patients is reported between 30% and 60% and pre-operative psychological distress is associated with poorer pain and functional outcomes after surgery. This study will use a mindfulness-based psychological intervention to enhance outcomes in people undergoing total joint arthroplasty and, in addition, will test hypotheses about coping with chronic illness in an aged population. This study is the first of its kind and will provide a greater understanding of the role of a mental health enhancement program on the physical recovery of total joint arthroplasty patients.

Methods/design: One hundred and fifty people with end-stage arthritis on the waiting list for total hip or knee arthroplasty will be recruited and randomly allocated to one of two groups using computer-generated block randomisation. A randomised controlled trial adhering to CONSORT guidelines will evaluate the efficacy of a mindfulness training program (weekly group-based classes in mindfulness practice, 2 ½ hours, for 8 weeks plus a 7-hour Saturday session in Week 6) prior to total joint arthroplasty, compared to a “standard care” group who will undergo routine total joint arthroplasty. Primary outcomes will be evaluated by a blinded examiner at baseline, 3 and 12 months post-surgery, using a validated self-reported pain and physical function scale. Secondary outcomes will include i) a range of validated measures of psychological wellbeing and ii) health economic analysis. All analyses will be conducted on an intention to treat basis using linear regression models. Health economic modelling will be applied to estimate the potential cost-effectiveness of mindfulness training and total joint arthroplasty.

Trial registration: Australian New Zealand Clinical Trials Registry (ANZCTRN12611001184965). Date of registration; 15th November 2011.



Knowles, S., Swan, L., Salzberg, S., Castle, D., & Langham, R. (2014). Exploring the Relationships Between Health Status, Illness Perceptions, Coping Strategies And Psychological Morbidity in A Chronic Kidney Disease Cohort. American Journal of the Medical Sciences. 348(4):271-6. doi: 10.1097/MAJ.0000000000000242.

Background: Using the common sense model of illness adjustment, this study aimed to explore the impact of chronic kidney disease (CKD) on individual illness perceptions, coping styles and psychological well-being.

Methods: Eighty individuals (50 men and 30 women) with an average age of 62.66 years (standard deviation, 11.98) were included in the study. All participants were under the care of the Renal Unit of a metropolitan tertiary referral hospital. Twenty-nine patients (36%) had CKD stage 3b-4, and 51 (64%) had CKD stage 5 (or end stage kidney disease [ESKD]). Disease severity was evaluated using the health perceptions questionnaire, coping styles assessed with the Carver brief COPE scale, illness perceptions explored with the brief illness perceptions questionnaire and anxiety and depression measured using the hospital anxiety and depression scale.

Results: The hospital anxiety and depression scale assessment revealed 13 patients (16.3%) with moderate or severe anxiety and 6 (7.5%) with moderate depression. Consistent with the common sense model, disease activity had a significant direct influence on illness perceptions, while, in turn, illness perceptions had a significant direct influence on depression and anxiety. Adaptive and maladaptive coping were found to mediate the relationship between illness perceptions, and anxiety and depression.

Conclusions: The results provide evidence that it is the perception of an illness rather than the actual symptoms themselves that best account for adaption to CKD. These findings suggest that intervention strategies aimed at increasing psychological well-being need to focus on changing illness perceptions rather than improving symptoms of CKD or coping mechanisms.