RESEARCH ARTICLE Changes in Activity and Interest in the Third and Fourth Age: Associations with Health, Functioning and Depressive Symptoms Kathryn Betts Adams 1, * ,† , Amy Restorick Roberts 1 & Marilyn B. Cole 2 1 Mandel School of Applied Social Sciences, Case Western Reserve University, Cleveland, OH 44106, USA 2 Quinnipiac University, Hamden, CT 06518, USA Abstract This study examines the changes in activity investment among older adults and the role of these changes in the relationship between health limitations and depression. Residents of six senior living facilities (N = 178) completed questionnaires including the Geriatric Depression Scale, health and functioning measures and the Revised Change in Activity and Interest Index (CAII-R) which measures self-perceived changes in the level of investment in social and leisure activities among older adults. Respondents indicated more disengagement from CAII-R subscales Active Instrumental (AI) and Active Social (AS) and increased engagement in Passive Social Spiritual. Fourth Age adults (age 80+) reported greater reductions in AI than Third Age adults (age 64–79). Reduced AS investment had the strongest association with depression and mediated the relationship between poor health or functioning and depression. These categories of activity may guide occupational therapy practitioners and other health providers in selecting the focus of intervention for older clients according to their identified life stage. The study provides evidence of distinct differences in interests within the parameters of normal aging and a baseline from which to assess the impact of illness and disability on the activity choices for clients in different life stages. Copyright © 2010 John Wiley & Sons, Ltd. Received 13 July 2010; Revised 7 September 2010; Accepted 8 September 2010 Keywords social activity; leisure activity; depression; adult development; older adults *Correspondence Kathryn Betts Adams, Mandel School of Applied Social Sciences, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA. † Email: kathryn.adams@case.edu Published online in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/oti.304 Introduction Successful and productive aging are seen as hallmarks of current gerontological theory and practice (Rowe and Kahn, 1998; Moody, 2001; Depp and Jeste, 2006). Yet, as people live longer, the prevalence of chronic illness and disability among older adults is high. Currently, 80% of people aged 65 years and over have at least one chronic illness and 50% have two or more (National Center for Chronic Disease Prevention and Health Promotion, 2009). Modification of activities and interests may be necessary to adapt to current functional or social limi- tations. This is particularly true as older adults cross from the Third Age, the years from approximately 65–79, when they are likely to be relatively healthy and independent, into the Fourth Age of 80 and older (Laslett, 1991; Baltes, 1997). The literature generally confirms that adults over 75 years participate in fewer Occup. Ther. Int. (2010) © 2010 John Wiley & Sons, Ltd.