Psychophysiology in pursuit of psychopathology

Psychophysiological measures continue to be an important tool for classifying disorders, for investigating antecedents and manifestations of psychological disorders, and for clarifying the effects of psychological and pharmacological treatments. Because they tap processes not readily observed or reported by individuals, these measures complement self-report, behavioral performance, and diagnostic interview data, and thereby bridge the gap between physiology and observed or reported phenomena (Lang, 1968, 1978; Kozak & Miller, 1982). Efforts to address this gap have grown exponentially in the past two decades, driven in part by the emergence of endophenotypes to advance causal understanding of psychopathology (Miller & Rockstroh, 2013), and psychophysiological measures have proven to be invaluable in combination with other biological measures (e.g., genetic and endocrine measures) for this purpose. This chapter provides an overview of established and evolving approaches to the use of psychophysiology in studying psychopathology. The chapter touches on some philosophical issues in psychophysiological research and selectively reviews contributions of psychophysiological approaches to common and costly psychological conditions, including anxiety, depression, and schizophrenia. In view of the rising prominence of the Research Domain Criteria (RDoC) initiative, study results are organized with reference to transdiagnostic, dimensional factors rather than categorical diagnoses. Potential challenges to using psychophysiological methods in this domain are outlined, suggestions for future research are noted, and guidelines for young investigators establishing new labs are offered. The review is necessarily illustrative rather than exhaustive (see also Edgar, Keller, Heller, & Miller, 2007; Keller, Hicks, & Miller, 2000), but the topics addressed have broad relevance to the study of psychopathology using psychophysiology. HISTORICAL CONTEXT OF THE PSYCHOPHYSIOLOGICAL STUDY OF PSYCHOPATHOLOGY Physiological systems have been implicated in efforts to understand psychopathology at least since Hippocrates included blood, bile, and phlegm in his theory of mental illness. More recent psychophysiological approaches have proven to be more generative, and prevailing theories have provided the blueprint for much of the best empirical work in an era, even though not all of these frameworks have withstood investigation. The concept of non-specific reactivity influenced early psychophysiological investigations of psychopathology. To account for blunted affect and behavioral withdrawal in patients diagnosed with depression or schizophrenia, for example, researchers invoked abnormal physiology as a potential contributor to emotional disorders.