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Synchrony of Change in Depression and Disability What Next? THE ARTICLE by Judd et al1 from the Collaborative Program on the Psychobiology of Depression from the National Institute of Mental Health (Bethesda, Md) confirms and extends earlier longitudinal work on the synchrony of change in depression severity and level of psychosocial disability. These earlier naturalistic studies2-4 found that disability was reduced among patients in primary care whose depressive and anxiety disorders improved, while, in contrast, patients whose psychological illness ran a chronic course maintained elevated disability levels 1 to 3 years later. Judd et al now show that the synchrony of change in depression severity and level of disability remains at the within-subject level over 10 years on average. Increments in depressive symptom severity were associated with increments in disability, and reductions in depressive symptom severity were associated with reductions in disability. What is new and exciting in their work is the combination of monthly assessments of symptoms and psychosocial functioning over an extended period with the application of recently developed advanced statistical methods, which comprise the so-called random regression model. MEASUREMENT OF DISABILITY Notwithstanding these innovative features, there may be some problems with their measurement of disability. The assessments of psychosocial functioning apparently counted only impairments in functioning that were attributable to depressive symptoms. While this does not imply a rating of impairment in those with depressive illness, it seems to imply a rating of no impairment in those without depressive symptoms. The rating of only depression-associated impairment may have produced spurious association. This risk may have been further enhanced by the use of the same interviewer for rating depression and disability and the exclusive reliance on interviewers at the expense of other, more objective indicators of disability. Because other studies2, 3 suggest that similar, albeit less strong, associations would have been observed if disability was measured completely independent of psychological state, we do not think that their procedures have seriously biased their findings. It would be reassuring, however, if future disability assessments included independent sources (family members or employers) or performance-based data (absenteeism or productivity). ADVANCES IN THE FIELD Considerable progress has been made in understanding the relationship between depression and disability since the introduction of the International Classification of Impairments, Disabilities and Handicaps5 in 1980 and the landmark Medical Outcome Study by Wells et al6 in 1989. The triad of impairment, disability, and handicap provided the framework for expanding disease concepts to include their effect on physical and psychosocial functioning. The Medical Outcome Study found that people with depression showed similar or poorer functioning than patients with chronic medical diseases, except in cases of patients with advanced coronary heart disease. The major findings of subsequent studies include the following: 1. The association of major and minor depression and depressive symptoms with disability is common in all cultures.7 The depression-disability relationship was not limited to the United States and European countries with highly developed economies and social welfare systems, but was also found in Asian, South American, and African countries. 2. Depression is a risk factor for onset of both physical and psychosocial disability.8-12 There are now at least 5 prospective studies reporting that preexisting depression is a risk factor for onset of disability.8-12 3. Effective treatment of depression improves functional outcomes. Five13-17 of 618 randomized, controlled trials that included good measures of disability have reported favorable disability outcomes in the experimental treatment group relative to usual care. There is also some evidence that a comprehensive depression training program for primary care physicians that included substantial hands-on learning improved disability outcomes among patients with depression of recent onset.19, 20 4. While these studies collectively suggest a causal effect of depression on psychosocial disability, part of the association may be due to effects of disability on depression. In older populations with high prevalences of chronic medical disease, limitations in activities of daily living have been found to predict onset and worsening of depressive illness.21-23 Consequently, the association between depression and disability might be due to bidirectional effects among depression, physical limitations, and psychosocial disability, in particular in older people and younger medical patients. THE FUTURE OF RESEARCH What is the future of research in the field now that it has progressed so far? What research questions need to be addressed? What steps need to be taken to improve functional outcomes of psychological illness on a population basis? One promising direction is the conceptualization of disability in terms of social role performance.24 We lack insight into the development and course of the behavioral effects of depression on disability in social role performance. Is there a hierarchical structure in role disability? Work on severe mental illness suggests that social activities and family roles are the first to manifest disability, followed by the work role and, finally, the self-care role.24 Do loss and recovery of social role performance among persons with depression follow a similar pattern? We know little about the lag times between onset and remission of psychological impairments and associated effects on social role functioning. The evidence of disability associated with medical disease as a risk factor for depression elicits intriguing questions on bidirectional effects between depression and disability. To what extent does disability, triggered by medical disease or social stress, propel the onset and maintenance of depression? Further research on the complex, possibly multidirectional effects among physical disease, depression, and physical and social role disability is needed. Modifying influences is another concern. The association between psychological illness and psychosocial dysfunction is strong, but not absolute. Some people with depression function rather well. The question here is what environmental and psychological factors dampen or enhance the effect of psychopathology on disability. Such knowledge may enhance the effectiveness of treatments for depression, as well as provide possible benefits for disability outcomes. PUBLIC HEALTH AND THE ORGANIZATION OF HEALTH CARE Although understanding of the causal relationships between depression and disability is far from perfect, there is now substantial evidence that improved treatment of depression reduces social role disability. In 1992, the finding of synchrony of change led us to conclude that "At present, there is an urgent need for randomized controlled trials of treatment of depressive illness . . . to assess effects on functional disability. . . . If such effects were reliably observed . . . current efforts to increase the recognition and effective management of depression by health care providers would be markedly advanced."2 Now, at the turn of the century, these trials have been performed. The public health challenge now is to organize health care systems so that they are capable of providing effective treatment to all people with depressive illness. Effective treatments are not sufficient; we also need effective health care systems capable of disseminating those treatments to entire populations.25 It is heartening to see the progress that has been made in the field in the 1990s, from epidemiological research demonstrating the depression-disability association to randomized controlled trials of interventions that improved both depression and disability.26 The public health challenge for the next decade is to develop dissemination strategies that ensure effective treatment of depressive illness on a population basis. Beyond that, there remains an urgent need for greater understanding of the mechanisms and effective management of disability due to psychological illness than currently exists. Although rapid progress has been made, depression remains one of the leading causes of disability throughout the world.27 Author/Article Information Johan Ormel, PhD Department of Psychiatry University of Groningen The Netherlands and Institute of Psychiatry Kings College London, England Michael Von Korff, ScD Seattle, Washington, USA Archives Of General Psychiatry Vol. 57 No. 4, April 2000 http://archpsyc.ama-assn.org/issues/v57n4/full/ycm9432.html 2000 American Medical Association. All rights reserved. janet paterson 53 now / 41 dx / 37 onset a new voice: http://www.geocities.com/janet313/ 613 256 8340 PO Box 171 Almonte Ontario Canada K0A 1A0