Commentary: Understanding Somatic Symptoms: From Dualism to Systems, Diagnosis to Dimensions, Clinical Judgement to Clinical Science Free

The study of persistent somatic symptoms has been fraught with controversy regarding etiology (mind vs. body), classification (hysteria, somatization disorder, somatic symptom disorder), and nomenclature (e.g., functional, psychogenic, idiopathic, medically unexplained). Patients with somatic symptoms not adequately explained by known physical disease are common across all health care specialties and often generate high health care costs without receiving effective treatment. These patients have been the subject of extensive research in both medicine and the behavioral sciences.

With their 1984 paper, Ernst and colleagues introduced research on persistent somatic symptoms to the field of pediatric psychology (Ernst, Routh, & Harper, 1984, reprinted in this issue of the Journal of Pediatric Psychology). They conducted their research at a time when pediatric psychology was on the cusp of paradigm shifts still underway today:

1. Conceptual frameworks are changing from mind-body dualism to systems.

2. The focus of assessment is shifting from diagnosis to dimensions.

3. Methods of study are changing from clinical judgement to clinical science.

In this commentary I review how these changes have impacted, and will continue to impact, research on children’s somatic symptoms. I use the term “somatic symptoms” descriptively without assumptions about underlying psychopathology or organic disease.

Conceptual Frameworks: From Dualism to Systems

Western medicine’s mind-body dualism constituted the initial framework for research on somatic symptoms, that is, the subjective experience of bodily discomfort (e.g., pain, nausea, heart palpitations). When medical evaluation ruled out organic etiology, psychological etiology became the most likely explanation for somatic symptoms. For example, from a psychoanalytic perspective, symptoms without underlying disease reflected the somatic expression of emotional distress, as in the example of a condition known as hysteria (Guze, 1975). In 1980, the term “hysteria” was replaced by somatization disorder, a new diagnostic category defined by the third edition of the Diagnostic and Statistical Manual for Mental Disorders (DSM-III; American Psychiatric Association [APA], 1980). The DSM-III rejected the traditional psychoanalytic framework in favor of an atheoretical, descriptive approach to somatic symptoms (North, 2015). Thus, DSM-III criteria for somatization disorder required that symptoms be medically unexplained but did not specify a psychological or other etiology.

Lipowski’s widely cited definition of the “concept” of somatization, like the DSM-III “diagnosis” of somatization disorder, also was atheoretical and descriptive (Lipowski, 1988). Lipowski defined somatization as “a tendency to experience and communicate somatic distress and symptoms unaccounted for by pathological findings, to attribute them to physical illness, and to seek medical help for them;” moreover, Lipowshi asserted that somatization “should not be considered to be in any sense abnormal or a medical or psychiatric problem” (Lipowski, 1988, p. 1359). Nonetheless, somatization was associated with a DSM-III psychiatric diagnostic category and the dominance of mind-body dualism implied, if only by default, a psychological etiology for symptoms not explained by identifiable disease.

The study by Ernst et al. (1984) illustrates the influence of mind-body dualism in pediatric psychology. Building on pediatricians’ observation that patients with medically unexplained recurrent abdominal pain (RAP) often complain of other somatic symptoms without detectable organic etiology (Apley,1975; Oster, 1972), they hypothesized that in some patients RAP might be a precursor to later onset DSM-III somatization disorder. They grouped RAP patients according to the presence versus absence of organic disease and reviewed patients’ medical charts for symptoms listed in the DSM-III criteria for somatization disorder (APA, 1980). Finding that the number of these symptoms increased with chronicity of patients’ abdominal pain, but only for patients without organic disease, they interpreted results as preliminary evidence for a “chronic, polysymptomatic hysterical disorder beginning in childhood.” Thus, mind-body dualism informed the study design and fostered an “either-or” interpretation of symptom etiology in this early pediatric psychology research.

In the last several decades, systems theories have gained ascendance in health-related research (Sturmberg, Martin, & Katerndahl, 2014), providing a strong theoretical foundation for research on somatic symptoms that often has been missing in studies of the concept of somatization (Crombez, Beirens, Van Damme, Eccleston, & Fontaine, 2009). Whereas the biomedical model reduced somatic symptoms to disorders of the mind versus body, the holistic perspective of systems thinking stimulates a search for nonlinear interacting mechanisms of illness as experienced by individuals in their biopsychosocial context (Sturmberg et al., 2014). For example, Craig’s social communication model of pain has stimulated investigation of how the social context influences and is influenced by children’s somatic complaints (Craig, 2015). Similarly, our research on functional abdominal pain has been guided by a conceptual model (Walker,1999) that places children with persistent somatic symptoms in a developmental and psychosocial context. This model has stimulated research on the relation of pain threat appraisal and coping (Walker, Smith, Garber, & Claar, 2005), social and academic competence (Walker, Garber, & Greene, 1994), parent behavior (Levy, 2011; Stone & Walker, 2017; Stone et al., 2018; Walker et al., 2006), daily stressors and central nervous system modulation of pain (Bruehl, Dengler-Crish, Smith, & Walker, 2010; Morris et al., 2016, Sherman et al., 2015) to the severity and persistence of children’s somatic symptoms and disability. Other important conceptual models focus on the relation of family factors to the development and perpetuation of children’s somatic symptoms (Hulgaard, Dehlholm-Lambertsen, & Rask, 2019; Stone & Wilson, 2016). Thus, systems thinking is propelling research beyond mind-body dualism and toward integration of psychological, biological, and social contextual factors in understanding somatic symptoms in children and adolescents.

Focus of Assessment: From Diagnosis to Dimensions

The DSM-III criteria for somatization disorder (APA, 1980) included the presence of persistent medically unexplained somatic symptoms (14 for women, 12 for men) from a list of 37 symptoms with onset before age 30 years. These criteria were developmentally inappropriate for children, and thus children rarely were diagnosed with somatization disorder (Schulte & Petermann, 2011). Nonetheless, children frequently presented to pediatric clinics with RAP, headache, and other somatic complaints that defied medical explanation and were on the symptom list for somatization disorder (Campo, Jansen-McWilliams, Comer, & Kelleher, 1999; Garralda, 2010). To assess variability in the severity and functional disability associated with children’s somatic symptoms, pediatric research needed an alternative to DSM-III’s categorical classification of children based on whether they met psychiatric diagnostic criteria for somatization disorder.

To this end, my colleagues and I developed dimensional measures of children’s somatic symptoms and health-related functional disability. These measures were grounded in the assumption that somatic symptoms and functional disability each exist on a continuum and may be present to some degree even in healthy youth. Thus, we developed the Children’s Somatic Symptom Inventory (CSSI), to assess somatic distress—the extent to which children feel “bothered” by each of 24 somatic symptoms (Stone et al., 2019; Walker, Beck, Garber, & Lambert, 2009; Walker & Garber, 2018; Walker, Garber, & Greene, 1991). Originally named the Children’s Somatization Inventory because many of the items were included in the criteria for somatization disorder, it was renamed the CSSI to further emphasize that the measure does not assess psychiatric disorder but rather a continuum of somatic distress (Walker & Garber, 2018).

We developed the Functional Disability Inventory (FDI; Claar & Walker, 2006; Walker & Greene, 1991) to address the need for a measure to assess the impact of somatic distress on children’s physical and psychosocial functioning in their everyday social roles. The FDI assesses the extent to which children perceive that their “physical health” limits their daily activities. Together, the CSSI and FDI capture children’s experience of somatic symptoms and health-related impairment independent of any medical or psychiatric diagnosis.

In addition to these dimensional measures of symptoms and impairment, dimensional measures have been developed to assess psychological, biological, and social processes associated with children’s somatic complaints, particularly chronic pain that persists without clear pathophysiology. For example, recent research has included dimensional measures of children’s pain beliefs and coping (Simons, Sieberg, Carpino, Logan, & Berde, 2011; Stone, Walker, Laird, Shirkey, & Smith, 2016), parent modeling of pain behavior (Stone & Walker, 2017), and parent responses to children’s symptoms (Goubert, Eccleston, Vervoort, Jordan, & Crombez, 2006; Noel et al., 2015; Stone, Bruehl, Smith, Garber, & Walker, 2018). Although initially developed for research on chronic pain and somatic symptoms without apparent disease, these measures assess processes that operate across patient groups and are being used in research on pediatric patients with significant disease (e.g., Levy et al., 2016; Reed-Knight et al., 2017).

In a related development, in 2009 the National Institute of Mental Health initiated the Research Domain Criteria (RDoC) project to develop a dimensional transdiagnostic approach to understanding mental disorder (Appelbaum, 2017). The RDoC project proposes dimensional assessment of cognitive, emotional, social, and physiological processes across diagnostic groups. This framework is relevant for research on pediatric somatic symptoms in that processes contributing to somatic symptoms operate across diagnostic entities (Chalder & Willis, 2017). For example, parasympathetically mediated low heart rate variability is a biological process associated both with long-term persistence of pediatric functional abdominal pain in our research (Walker et al., 2017) and with a range of psychological and somatic pathological conditions, including immune dysfunction, in other populations (Thayer & Brosschot, 2005). Similarly, parent attention and reassurance are interpersonal processes that affect the severity of symptom complaints in youth with and without functional abdominal pain (Blount et al., 1989; Walker et al., 2006). Thus, dimensional measures allow researchers to transcend categorical classification and instead focus on understanding variability in the severity, disability, and persistence of somatic symptoms with and without underlying physical or mental disorder.

Methods of Study: From Clinical Judgement to Clinical Science

Clinical judgement was the primary method used in early studies of pediatric somatic symptoms. Apley’s landmark studies of RAP, for example, drew their data from medical evaluations (Apley, 1975) and did not employ statistical methods. Data for Ernst and colleague’s study of children’s somatic symptoms (Ernst et al., 1984) also were derived from clinical judgement—physicians’ clinical notes in medical charts. Notably, however, Ernst and colleagues introduced quantitative methods of clinical science into their research. Independent raters counted symptoms in medical charts from a standard symptom list, inter-rater reliability was established, and group differences were evaluated using analysis of variance.

Subsequent advances in computing and statistical methods have given us the means to test complex relations among multiple factors over time. For example, multivariate statistical methods have been used to characterize and predict symptom trajectories (Mulvaney, Lambert, Garber, & Walker, 2006; Kashikar-Zuck et al., 2019; Simons et al., 2018), identify patient subgroups that may vary in treatment needs (Walker, Sherman, Bruehl, Garber, & Smith, 2012), and evaluate the efficacy of behavioral treatments in reducing somatic symptoms in randomized clinical trials (Levy et al., 2010; Palermo et al., 2016; Sieberg et al., 2017).

Technology for recording physiological variables has given us the means to evaluate the relation between physiological processes and somatic symptoms. We and others have used electrocardiography to assess heart rate variability as a biomarker for autonomic nervous system response differences between youth with and without chronic pain and somatic symptoms (Chudleigh et al., 2019; Evans et al., 2013; Walker et al., 2017). Polysomnography and actigraphy have established a bidirectional relation between sleep quality and pain (Lynch, Dimmitt, & Goodin, 2018; Valrie, Bromberg, Palermo, & Schanberg, 2013). Neuroimaging techniques have begun to describe neurological processes associated with persistent pain (Simons et al., 2014; Linnman et al., 2013). Finally, quantitative sensory testing is being used in youth with and without persistent pain to assess their perception of somatic discomfort induced in the laboratory (Morris et al., 2015, 2016; Sherman, Morris, Bruehl, Westbrook, & Walker, 2015; Williams, Heitkemper, Self, Czyzewski, & Shulman, 2013). Thus, advances in technology now allow us to study somatic symptoms under experimental conditions and to link the subjective experience of somatic symptoms with objective measures of biological processes.

Conclusions

Systems models of multiple interacting factors that contribute to somatic symptoms, dimensional measures that assess variability in processes and outcomes hypothesized by these models, and advances in statistics and technology have driven substantial gains in our understanding of somatic symptoms in children and adolescents. Research in this area is increasingly grounded in conceptual models that integrate mind, body, and contextual factors in understanding the experience of somatic symptoms regardless of the presence or absence of underlying physical or mental disorder. This approach holds promise for generating knowledge that legitimizes the experience of youth with persistent somatic symptoms and leads to effective interventions that benefit these youth and their families.

Funding

The research is supported by National Institute of Health (NIH) grant R01H0076983.

References