Psychological Medicine

  • Psychological Medicine / Volume 42 / Issue 10 / October 2012, pp 2057-2069
  • Copyright © Cambridge University Press 2012 The online version of this article is published within an Open Access environment subject to the conditions of the Creative Commons Attribution-NonCommercial-ShareAlike licence <http://creativecommons.org/licenses/by-nc-sa/2.5/>. The written permission of Cambridge University Press must be obtained for commercial re-use.
  • DOI: http://dx.doi.org/10.1017/S0033291712000402 (About DOI), Published online: 15 March 2012
  • OPEN ACCESS

Original Articles

Is there a bidirectional relationship between depressive symptoms and cognitive ability in older people? A prospective study using the English Longitudinal Study of Ageing

C. R. Galea1a2 c1, M. Allerhanda2 and I. J. Dearya2 for the HALCyon Study Team

a1 MRC Lifecourse Epidemiology Unit, University of Southampton, Southampton, UK

a2 Centre for Cognitive Ageing and Cognitive Epidemiology, Department of Psychology, University of Edinburgh, Edinburgh, UK

Abstract

Background Cross-sectional surveys of older people commonly find associations between higher levels of depressive symptoms and poorer cognitive performance, but the direction of effect is unclear. We examined whether there was a bidirectional relationship between depressive symptoms and general cognitive ability in non-demented older people, and explored the role of physical health, smoking, exercise, social class and education as potential confounders of this association and as possible determinants of the rate of change of cognitive decline and depressive symptoms.

Method The English Longitudinal Study of Ageing consists of people aged 50 years and over. Cognitive function and self-reported depressive symptoms were measured in 2002–2003, 2004–2005, 2006–2007 and 2008–2009. We fitted linear piecewise models with fixed knot positions to allow different slopes for different age groups. Analyses are based on 8611 people.

Results Mean cognitive function declined with age; there was no trend in the trajectory of depressive symptoms. Better cognitive function was associated with less depression up to the age of 80 years. Greater depression was associated with a slightly faster rate of cognitive decline but only in people aged 60–80 years. There were no consistent associations across age groups between sex, smoking, education, social class, exercise or number of chronic physical illnesses and the rate of change of cognitive decline or depressive symptoms.

Conclusions In this longitudinal study of older people, there was no consistent evidence that being more depressed led to an acceleration in cognitive decline and no support for the hypothesis that there might be reciprocal dynamic influences between cognitive ability and depressive symptoms.

(Received June 01 2011)

(Revised February 03 2012)

(Accepted February 07 2012)

(Online publication March 15 2012)

Correspondence

c1 Address for correspondence: C. R. Gale, Ph.D., MRC Lifecourse Epidemiology Unit (University of Southampton), Southampton General Hospital, Southampton SO16 6YD, UK. (Email: crg@mrc.soton.ac.uk)

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