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
What this study found
The omega-3 interventions improved depressive symptoms, with both EPA-rich and DHA-rich fish oils reducing GDS scores versus linoleic acid control; the DHA group showed a significant time-by-treatment effect (Estimate 2 1.40, SE 0.53, t 2 2.62, P 0.01, 95% CI 2 2.47, 2 0.32), and improved GDS scores were correlated with increased DHA plus EPA (r 0.39, P 0.02). DHA also improved Initial Letter Fluency versus control (Estimate 4.16, SE 1.99, t 2.09, P 0.04, 95% CI 0.12, 8.21). There were no consistent treatment effects on other cognitive measures or overall quality of life, although Digits…
- Study & population
- Randomized controlled trial with treatment allocation by minimisation based on age, sex, and depressive symptoms.
- Intervention
- Participants were randomized to four capsules daily for 6 months of either DHA-rich fish oil providing 1.55 g DHA plus 0.40 g EPA per day or EPA-rich fish oil providing 1.67 g EPA plus 0.16 g DHA per day, compared with a linoleic acid control.
- Key limitation
- The trial was small, with only 6 months of follow-up and relatively few completers in each active arm.
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Open PDFOriginal 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.