Depression and Cognition: How Do They Interrelate in Old Age? Tessa N. van den Kommer, Ph.D., Hannie C. Comijs, Ph.D., Marja J. Aartsen, Ph.D., Martijn Huisman, Ph.D., Dorly J.H. Deeg, Ph.D., Aartjan T.F. Beekman, M.D., Ph.D. Objectives: To disentangle the reciprocal effects between depressive symptoms and cognitive functioning over time and to study the association between changes in their trajectories using 13 years of follow-up. Design and Participants: Data were used from five waves of the population-based Longitudinal Aging Study Amsterdam. Subjects were included if data was present on depressive symptoms and cognitive performance on at least two occasions, which resulted in a study sample of N ¼ 2,299. Measurements: Depressive symptoms were assessed with the Center for Epidemio- logic Studies Depression Scale. Cognitive functioning was assessed using the Mini- Mental State Examination (general cognitive functioning) and timed coding task (speed of information processing). Results: Cross-domain latent change analyses showed that depression at baseline predicted both decline of general cognitive func- tioning and information processing speed, independent of relevant covariates. Conversely, information processing speed at baseline, but not general cognitive functioning was related to the course of depressive symptoms. The course of cognitive functioning was not significantly associated with the course of depressive symptoms. Conclusion: Depressive symptoms in older patients flag an increased likelihood of cognitive decline. This effect is considerable and may be due to several underlying mechanisms. The likelihood of the relationship reflecting either a causal effect of depression on cognitive decline, or a common cause, or both, should be estimated. Likewise, older persons with more limitations in information processing speed specifically are more vulnerable to increases in depression. (Am J Geriatr Psychiatry 2013; 21:398e410) Key Words: Bidirectional relationship, cognitive decline, depression, elderly I t is generally acknowledged that depression and cognitive impairment are closely associated in old age. Both conditions are prevalent among older persons and their interrelationship complicates both diagnosis and treatment. Cognitive deficits may also be part of the depressive syndrome. 1 These cognitive problems often disappear when depression is treated. In addition, depression may arise in the context of cognitive decline, as a direct consequence of brain abnormalities and neurodegeneration or due to psychosocial consequences of developing dementia. 2e5 Received May 17, 2011; revised October 6, 2011; accepted November 30, 2011. From the Departments of Epidemiology and Biostatistics (TNK, MH) and Psychiatry (HCC, DJHD, ATFB), EMGO Institute for Health and Care Research, VU University Medical Center; and Department of Sociology (MJA, MH), VU University, Amsterdam, The Netherlands. Send correspondence and reprint requests to: A.T.F. Beekman, M.D., Ph.D., VU University Medical Center and GGZ in Geest, A.J. Ernststraat 1187, 1081 HL Amsterdam, The Netherlands. e-mail: a.beekman@ ggzingeest.nl Ó 2013 American Association for Geriatric Psychiatry http://dx.doi.org/10.1016/j.jagp.2012.12.015 398 Am J Geriatr Psychiatry 21:4, April 2013