Self-efficacy beliefs mediate the relationship between subjective cognitive functioning and physical and mental well-being after hematopoietic stem cell transplant

Hematopoietic stem cell transplant (HSCT; also commonly known as bone marrow transplant) is an aggressive treatment for hematological malignancies that causes numerous physical and psychological difficulties, including significant distress and poor quality of life [1, 2]. Although previously a treatment of last resort, HSCTs are now indicated early in the course of many diseases. This shift in treatment strategy has resulted in improved survival rates [3, 4], but has also led to a greater focus on lingering side effects found among survivors. Researchers have recently begun to examine the potential neurotoxic effects of HSCT as well as the deleterious neurological impact of the cancers it treats. There are two ways in which such cognitive impairments have been measured: neuropsychological assessment (objective) and self-report measures of cognitive functioning (subjective). HSCT patients have impaired cognitive function using both forms of measurement [5–7]. However, in general, objective neuropsychological test results are not correlated with subjective cognitive functioning [7, 8]. Thus, patients may demonstrate deficits on neuropsychological tests but perceive little impairment in daily functioning, or they may demonstrate relatively normal neuropsychological test results despite perceiving considerable daily impairment. Despite the fact that subjective cognitive functioning is often not correlated with objective neuropsychological impairment, it is associated with poorer psychological adjustment and quality of life. For instance, Booth-Jones and colleagues [7] investigated HSCT patients who were 6-months post-discharge and found that poorer subjective cognitive functioning was associated with greater depressive symptomatology as well as poorer physical and mental quality of life. Similar associations have also been found in women receiving adjuvant therapy for breast cancer for whom self-reports of memory and concentration difficulties were associated with psychological distress and poorer quality of life [9]. Mechanisms through which subjective cognitive impairment affects distress and quality of life are not currently well-defined, but they are worth clarifying because they may be good targets for psychosocial interventions. One possible mechanism is suggested by Bandura’s social cognitive theory and its emphasis on self-efficacy, or “belief in one’s capabilities to organize and execute the courses of action required to manage prospective situations” [10]. HSCT survivors’ self-efficacy for managing symptoms is particularly likely to have implications for their well-being because of their high physical and psychosocial symptom burden after treatment [1]. Indeed, low self-efficacy has been associated with elevated psychological distress and poorer quality of life in other cancer patients [e.g., 11–13]. Thus, experiencing difficulties such as memory problems and poor concentration may cause survivors to doubt their ability to manage symptoms, which in turn may adversely affect their psychological adjustment and quality of life. Evidence from other patient populations supports the plausibility of such a mechanism. For example, in chronic pain patients, self-efficacy has been shown to mediate the relationship between self-reported pain intensity and outcomes such as disability and depression [14]. Self-efficacy for managing cognitive symptoms has also been found to mediate the relationship between community integration and global life satisfaction in patients with traumatic brain injury [15]. If self-efficacy were similarly conceptualized as a mediator among HSCT survivors suffering from subjective cognitive impairment, it might explain the link between subjective cognitive impairment and distress and poor quality of life. Thus, the purpose of the present study was to examine whether self-efficacy for symptom management mediates relations between subjective cognitive functioning and the following outcomes: psychological adjustment (i.e., depressed mood and anxiety), and health-related quality of life. We hypothesized that among HSCT survivors, poorer subjective cognitive functioning would be associated with lower levels of self-efficacy for symptom management, which would in turn be associated with poorer adjustment and quality of life.