British Journal of Nutrition

Human and Clinical Nutrition

Effects of n-3 fatty acids, EPA v. DHA, on depressive symptoms, quality of life, memory and executive function in older adults with mild cognitive impairment: a 6-month randomised controlled trial

Natalie Sinna1 c1, Catherine M. Miltea1, Steven J. Streeta2, Jonathan D. Buckleya1, Alison M. Coatesa1, John Petkova3 and Peter R. C. Howea1

a1 School of Health Sciences, Sansom Institute for Health Research, Nutritional Physiology Research Centre, University of South Australia, GPO Box 2471, Adelaide, SA 5001, Australia

a2 Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia

a3 Centre for Regional Engagement, University of South Australia, Adelaide, SA, Australia

Abstract

Depressive symptoms may increase the risk of progressing from mild cognitive impairment (MCI) to dementia. Consumption of n-3 PUFA may alleviate both cognitive decline and depression. The aim of the present study was to investigate the benefits of supplementing a diet with n-3 PUFA, DHA and EPA, for depressive symptoms, quality of life (QOL) and cognition in elderly people with MCI. We conducted a 6-month double-blind, randomised controlled trial. A total of fifty people aged >65 years with MCI were allocated to receive a supplement rich in EPA (1·67 g EPA+0·16 g DHA/d; n 17), DHA (1·55 g DHA+0·40 g EPA/d; n 18) or the n-6 PUFA linoleic acid (LA; 2·2 g/d; n 15). Treatment allocation was by minimisation based on age, sex and depressive symptoms (Geriatric Depression Scale, GDS). Physiological and cognitive assessments, questionnaires and fatty acid composition of erythrocytes were obtained at baseline and 6 months (completers: n 40; EPA n 13, DHA n 16, LA n 11). Compared with the LA group, GDS scores improved in the EPA (P = 0·04) and DHA (P = 0·01) groups and verbal fluency (Initial Letter Fluency) in the DHA group (P = 0·04). Improved GDS scores were correlated with increased DHA plus EPA (r 0·39, P = 0·02). Improved self-reported physical health was associated with increased DHA. There were no treatment effects on other cognitive or QOL parameters. Increased intakes of DHA and EPA benefited mental health in older people with MCI. Increasing n-3 PUFA intakes may reduce depressive symptoms and the risk of progressing to dementia. This needs to be investigated in larger, depressed samples with MCI.

(Received March 22 2011)

(Revised July 27 2011)

(Accepted July 27 2011)

(Online publication September 20 2011)

Correspondence:

c1 Corresponding author: Dr N. Sinn, fax +61 8 302 2794, email natalie.sinn@unisa.edu.au

Footnotes

Abbreviations: AA, arachidonic acid; GDS, Geriatric Depression Scale; LA, linoleic acid; MCI, mild cognitive impairment; WAIS III, Wechsler Adult Intelligence Scale