Fish fatty acids and mental health in older people

Research output: Thesisinternal PhD, WU

Abstract

Background
It has been suggested that the intake of fish and marine n-3 polyunsaturated fatty acids could protect against age-related cognitive decline and impaired mental well-being. However, results from observational studies are inconclusive and data from randomized controlled trials in older people without clinical dementia or depression are scarce. The objective of this thesis was to investigate the effect of daily supplementation with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on cognitive performance and mental well-being in an older non-clinical population. We also examined the effect of fish oil on gene expression profiles in white blood cells to identify early changes in pathways possibly related to mental health. Furthermore, we assessed the association of fish and EPA+DHA intake with mental health in different aging populations.

Methods
The effect of low and high doses of EPA+DHA (400 and 1,800 mg per day, respectively) on cognitive performance, several measures of mental well-being, and gene expression was examined in a 26-week randomized, double-blind, placebo-controlled trial. This study was conducted in 302 individuals aged 65 years or older with no clinical diagnosis of dementia or depression. Furthermore, the cross-sectional association between fatty fish and EPA+DHA intake with cognitive performance and the association with cognitive change during 6 years of follow-up was assessed in 1,025 aging US men who participated in the Veterans Affairs Normative Aging Study (NAS). In addition, the associations of EPA+DHA and fish intake with depressive symptoms and dispositional optimism were assessed in 644 free-living Dutch subjects with a history of myocardial infarction.

Results
Daily intake of low or high doses of EPA+DHA did not affect cognitive performance, mental well-being, anxiety, or quality of life, after 13 or 26 weeks of intervention. However, treatment with EPA+DHA for 26 weeks altered gene expression in white blood cells to a more anti-inflammatory and more anti-atherogenic profile. In elderly US men we found no association of fatty fish or EPA+DHA intake with cognitive performance or 6-year cognitive change. Intake of EPA+DHA was positively associated with dispositional optimism in subjects with a history of myocardial infarction. There was also a tendency for less depressive symptoms with a higher EPA+DHA or fish intake, but this association was no longer statistically significant after controlling for confounders.

Conclusion
Supplemental intake of EPA+DHA is unlikely to have a short-term impact on cognitive performance or mental well-being of older people without a clinical diagnosis of dementia or depression. Whether long-term intake of EPA+DHA and fish could be beneficial to the maintenance of cognitive performance or mental well-being of older people in Western populations still needs to be established.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Wageningen University
Supervisors/Advisors
  • de Groot, Lisette, Promotor
  • Kok, Frans, Promotor
  • Geleijnse, Marianne, Co-promotor
Award date18 Dec 2009
Place of Publication[S.l.
Print ISBNs9789085854715
Publication statusPublished - 2009

Keywords

  • mental health
  • mental ability
  • depression
  • fish oils
  • polyenoic fatty acids
  • elderly
  • aging
  • omega-3 fatty acids

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