Salivary cortisol, stress, and health in primary caregivers (mothers) of children with cerebral palsy

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Summary

This study evaluated level of salivary cortisol and perceived burden, stress and health of mothers and primary caregivers of children (4–11 years of age) with cerebral palsy (purpose group, n = 37) and those for mothers of children of the same age without developmental problems (control group, n = 38). Anthropometric and socioeconomic data were collected from the participants, who also completed the perceived stress questionnaire, the Burden Interview and the 36-Item Short Form Health Survey (SF-36). Cortisol level was assayed in saliva samples collected at various times in a single day and the area under the cortisol curve was then determined. Both groups presented low socioeconomic level and high, although equivalent, perceived stress index. However, the purpose group showed lower cortisol levels, as well as lower scores for many of the SF-36 domains related to physical well-being (physical functioning, role-physical, vitality, and general health) and social functioning. Nevertheless, bodily pain was also reported to be lower. For the control group, the area under the cortisol curve correlated negatively with mental health and social functioning. For the purpose group, where the burden is greater, no such correlation was found. It was concluded that mothers of healthy children leaving in unfavorable socioeconomic conditions face high levels of stress with the hypothalamus–pituitary–adrenal cortex axis function preserved. However, to the mothers of children with cerebral palsy, who live in even worse socioeconomic conditions and also have the burden of caring for a disabled child, the level of stress was overwhelming, to an extent that it impaired the hypothalamus–pituitary–adrenal cortex axis function, as well as reflecting negatively on certain aspects of their physical and psychological well-being. This must receive consideration during the treatment of the child, an approach which is in line with present day tendencies towards family-centered models of assistance to disabled children.

Introduction

Cerebral palsy is the most common physical disorder of childhood, affecting 2–3 out of every 1000 live births in Europe (Surveillance of Cerebral Palsy in Europe, 2000) and Canada (Smith et al., 2008), and up to 7 per 1000 in Brazil (Piovesana, 2002). The term cerebral palsy refers to a non progressive disorder of movement and posture causing functional limitations, secondary to a defect or lesion of the central nervous system during the early maturation of brain development (Piovesana, 2002, Pascual and Koenigsberger, 2003, Rosenbaum et al., 2007). Many children with cerebral palsy also show evidence of sensory and intellectual impairments and may face limitations in self-care functions such as dressing, feeding, bathing, and mobility. Such limitations, and the long term dependency they create, can place demands on caregivers that far exceed the usual requirements for developing children (Brehaut et al., 2004) and require changes in their parents’ lives, not only in relation to child care, but also to personal expectations. The birth of a disabled child is often seen by the parents as a personal failure. They feel pressured to accept a child who is different from what they had envisioned and who will exert great emotional and physical demands for which they may not feel prepared (Levitt, 2001, Rentinck et al., 2006, Ketelaar et al., 2008). In fact, there is evidence that mothers of children with developmental disabilities have higher rates of mental health problems than other mothers in the community (Singer, 2006, Bailey et al., 2007), and a very recent study demonstrated that mothers who were caring for children with autism reported a high rate of mental health problems that are reduced by the social support they receive (Sawyer et al., 2010).

One of the main challenges of these parents is to manage their child's chronic health problems effectively while meeting their needs of everyday living. In some cases, the provision of such intensive care can prove detrimental to their own physical health and psychological well-being and have an impact on family income, family functioning, and sibling adjustment (King et al., 1999). The daily burden of taking care of such a child is frequently taken on by the mother, but with poor or non-existing social support. The mothers of children with cerebral palsy must not only attempt to overcome the difficulties and complications arising from their children's condition, but may also be faced with the impossibility of satisfying their own social needs (Ones et al., 2005). As a consequence, these mothers are at greater risk of developing stress-related mental and psychological disorders.

Stress has been defined as the body's multi-system response to any challenge that overwhelms, or is judged likely to overwhelm, selective homeostatic response mechanisms (Day, 2005). Stress has been classically associated with over-activation of the hypothalamus–pituitary–adrenal axis, thus generating high serum and salivary levels of cortisol, which may even be a critical biological intermediary in the mechanism by which chronic stressors are able to trigger diseases (Miller et al., 2007). However, it is now accepted that insufficient glucocorticoid signaling or levels (hypocortisolism) may also play a role in the expression and development of various stress-related diseases, such as post-traumatic stress disorder, burnout, chronic fatigue syndrome, fibromyalgia, irritable bowel syndrome, lower back pain, atypical depression, chronic pelvic pain and endometriosis (Heim et al., 2000, Fries et al., 2005, Jerjes et al., 2006, Petrelluzzi et al., 2008, Tak and Rosmalen, 2010). Some studies have revealed hypocortisolism associated with exhaustion, a condition characterized by fatigue and loss of strength or vitality (Lindeberg et al., 2008, Kumari et al., 2009), while others have observed it in otherwise healthy individuals living under conditions of ongoing stress (Heim et al., 2000); still others, however, report especially high levels of cortisol associated with living under extremely unfavorable conditions (Garcia et al., 2008). Therefore, as Miller et al. (2007) point out, both too much and too little cortisol can be potentially detrimental. That is way alteration in salivary cortisol levels has been largely used as a biological marker of stress related to the care of patients with chronic diseases (Bauer et al., 2000, Vugt et al., 2005, Gallagher-Thompson et al., 2006, Brummett et al., 2008). However, as far as we know, there are no studies using both psychological and biological approaches to investigate stress in caregivers of children with cerebral palsy.

Surveys made in Canada (Brehaut et al., 2004, Raina et al., 2005), the United States (Davis et al., 2009) and Ireland (Byrne et al., 2010) using self-completed questionnaires and/or face-to-face interviews, have revealed that the parents of children with cerebral palsy are more likely to have a variety of physical and psychological health problems than parents of children without any disability, and many of these problems are consistent with a stress process model, in which stress for caregiving can directly or indirectly affect a variety of health aspects (Davis et al., 2009, Byrne et al., 2010). However, cortisol level has never been investigated in this population.

The hypothesis guiding the present study is that mothers and caregivers of children with cerebral palsy will present a stress level that is higher than that of mothers of children without any disability. This stress is presumed to be influenced by the burden of caregiving, and is expected to have an impact on their health and well-being. We assume that such stress will be reflected in the salivary cortisol levels, which are traditionally considered to be a biological marker of stress.

Section snippets

Subjects

Mothers and caregivers of children diagnosed with cerebral palsy were recruited using a public announcement in the out-patient Physiotherapy Service of the Child Neurology Clinic at the Campinas State University Hospital. In Brazil, such large hospitals serve most of the families of low socioeconomic status, where cerebral palsy is more likely to occur due to the precarious health care conditions available to mothers during pregnancy and birth. All mothers and caregivers of 4–11 year-old

Demographic and medical variables

The control and purpose groups were similar in regard to age of mothers and children evaluated, as well as the number of children in the family (Table 1). The percentage of mothers living in a stable relationship with a partner was also similar (83% for the control group and 79% for the purpose group). No significant stressful event during the preceding year was reported by 17 mothers in the control group and by 16 in the purpose group; a single such event was reported by 17 mothers in the

Discussion

The results presented here show that mothers of children with cerebral palsy reported facing a significantly greater burden than mothers of unimpaired young children, confirming that the special and constant care required by such children exerts special demands on the caregiving mothers (Raina et al., 2005, Rentinck et al., 2006, Ketelaar et al., 2008). The perceived stress index for mothers in the two groups, however, was equivalent with both groups scoring in the upper quartile of the scale (

Role of funding source

Funding for this study was provided by FAEP/UNICAMP; the FAEP had no further role in study design; in the collection, analysis and interpretation of data; in the writing of the report; and in the decision to submit the paper for publication.

Conflict of interest

None declared.

Acknowledgements

The authors would like to acknowledge the financial support of the “Foundation for the Support of Research of the State University of Campinas” (FAEP/UNICAMP), the Physiotherapy Service in the Child Neurology Clinic at the General Hospital of the State University of Campinas and the public educational system in the city of Campinas (State of São Paulo, Brazil) in permitting access to their patients and students, respectively. The authors also acknowledge Dr. D.M. Grassi-Kassisse for allowing

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