Ambulatory monitoring of biobehavioral processes in health and disease.

Ambulatory monitoring techniques have a long tradition in the study of biobehavioral processes and psychosomatic medicine. This is evidenced in several important publications in Psychosomatic Medicine dating back to the first half of the last century, which use ambulatory monitoring, ranging from ambulatory blood pressure monitoring to elucidate the white-coat and masked hypertension effects to carefully designed studies that use diary techniques for the assessment of self-reports of symptoms, behaviors, and attitudes. The advantages of ambulatory research are well known: it offers a unique opportunity to establish the ecological validity of results (1) and to investigate processes and dynamics that would go unrecognized in laboratory or survey studies, for example, diurnal cycles of affect and hormones. Our reasons for undertaking the endeavor of guest editing this special issue on ambulatory monitoring in Psychosomatic Medicine are straightforward. In the past decade, ambulatory monitoring has advanced in several respects that are highly relevant to biobehavioral research. These changes are summarized in Table 1 and include the following: substantial progress has been made in conceptual development and study design. The capabilities of physiological monitoring have been considerably expanded, not only for refinement of existing ambulatory monitoring systems but also by the availability of monitoring approaches for biosignals that could not be studied before, such as glucose or metabolites. The techniques and technology for studying self-reports with momentary real-time assessments and diary methods (2) have advanced and become part of the biobehavioral landscape. Statistical tools for the analysis of monitoring data have been refined, making it easier to take full advantage of the richness that lies in monitoring data for dynamics and process modeling. Moreover, ambulatorymonitoring in biobehavioral research is flourishing in several domains. These include the areas of patient-reported outcomes and monitoring approaches incorporating social context and environment. A final recent development could be labeled integration and exchange. Research on ambulatory monitoring has evolved from many different traditions (3), ranging from paper-pencil or computer-assisted diary techniques to assess self-reports that capture experiences and behavior to the monitoring of physiological measures in medicine and psychophysiology. This diversity is reflected in different terms and concepts, such as experience sampling method (4) and ecological momentary assessment (5)Vboth concepts pertaining to the assessment of self-reports and experienceVor the broader, overarching notion of ambulatory assessment (6). The past few years have seen an increasing exchange between these different traditions and disciplines, as evidenced by an integrative, comprehensive stateof-the-art textbook on daily life research methods (7) and the emerging Society for Ambulatory Assessment, which was formed in 2008 and brings together experts from different disciplines involved in ambulatory research. In this special issue, we opted for the broad term of ambulatory monitoring, encompassing diary self-reports and physiological monitoring. Previous special issues addressing ambulatory monitoring (8,9) addressed the diversity of applications in various disciplines using a ‘‘wide scope.’’ The present issue covers in-depth contributions to biobehavioral medicine and compiles a mixture of current original research and longneeded state-of-the-art reviews and conceptual contributions. This special issue is organized into three sections. The first section is devoted to current trends in ambulatory monitoring, including state-of-the-art review articles and research with novel ambulatory approaches. Conner and Barrett (10) set the stage with a position article on the future of ambulatory selfreports. They provide a novel theoretical framework for the assessment of self-reports and outline a possible link to neuroscience. Rose and colleagues (11) discuss the state of affairs concerning computer adaptive testing and item response theory approaches in ambulatory self-report research. In a conceptual article, Finan and colleagues (12) provide a conceptual framework linking molecular genetics approaches and ambulatory monitoring that have the potential to overcome shortcomings in molecular genetics. Finally, as a prominent example of advances in physiological monitoring, Wagner and colleagues (13) introduce methods for continuous glucose monitoring, which offer a wide range of applications, but until now, these have been largely neglected outside the field of diabetes research. The second section revolves around statistical issues and topics in data analysis, a field that saw rapid advances in the past years. Two contributions deal with the issue of capturing dynamics in ambulatory self-report data following two distinct statistical approaches: Crayen and colleagues (14) demonstrate the usefulness of latent Markov chain modeling for capturing dynamics, and Rosmalen and colleagues (15) build on a time series approach to solve similar problems and argue for an idiographic view in exploring dynamics. The contributors thankfully supplied supplementary online material including demo syntax, which will make the novel approaches much more accessible to the reader. Linking back to practical applications in patientreported outcome research, which are essential to testing new medicines and devices, Stone and colleagues (16) elaborate on deriving outcome indices from monitoring data in the realm of self-reported pain. In the third section, three selected domains are addressed: ambulatory monitoring of social environments and interactions, monitoring of salivary cortisol, and multimodal ambulatory DOI: 10.1097/PSY.0b013e31825878da EDITORIAL