Docosahexaenoic Acid and Cognition throughout the Lifespan

Abstract

Docosahexaenoic acid (DHA) is the predominant omega-3 (n-3) polyunsaturated fatty acid (PUFA) found in the brain and can affect neurological function by modulating signal transduction pathways, neurotransmission, neurogenesis, myelination, membrane receptor function, synaptic plasticity, neuroinflammation, membrane integrity and membrane organization. DHA is rapidly accumulated in the brain during gestation and early infancy, and the availability of DHA via transfer from maternal stores impacts the degree of DHA incorporation into neural tissues. The consumption of DHA leads to many positive physiological and behavioral effects, including those on cognition. Advanced cognitive function is uniquely human, and the optimal development and aging of cognitive abilities has profound impacts on quality of life, productivity, and advancement of society in general. However, the modern diet typically lacks appreciable amounts of DHA. Therefore, in modern populations, maintaining optimal levels of DHA in the brain throughout the lifespan likely requires obtaining preformed DHA via dietary or supplemental sources. In this review, we examine the role of DHA in optimal cognition during development, adulthood, and aging with a focus on human evidence and putative mechanisms of action.

Docosahexaenoic Acid

“…DHA is not an essential FA per se, because it can be metabolized to some extent from its essential precursor, a-linolenic acid [ALA (18:3n-3)], via a series of desaturations and elongations (1). Although ALA can be converted metabolically into EPA (20:5n-3) and on to DHA, the conversion rate is considered to be low in humans (2).…”

“…DHA is found in high concentrations in neuronal cell membrane phospholipids, where it can exert many physiologic roles including regulation of membrane fluidity, neurotransmitter release, gene expression, myelination, and cell differentiation and growth (1). Considering the low rate of de novo DHA synthesis from ALA, many researchers agree that DHA is required in the diet in order to reach and maintain adequate brain and eye DHA concentrations and related neurologic and visual functions (1,3). DHA is accumulated rapidly in the brain and eye during gestation and early infancy and is essential for the growth and maturation of the infant's brain and retina.…”

“…Evidence-based recommendations from randomized controlled studies suggest that infant formula should be enriched with DHA (generally between 0.2% and 0.35% of total FAs) for optimal brain and visual development in both preterm and full-term infants. Consumption of preformed DHA in the diet has been associated with many beneficial effects on cognitive functions throughout the life course (1). Several observational studies have reported, among the potential beneficial effects in adults, a lower risk of dementia and cognitive decline with a higher intake of EPA plus DHA, although results from clinical studies are far less consistent (1).…”

“…Consumption of preformed DHA in the diet has been associated with many beneficial effects on cognitive functions throughout the life course (1). Several observational studies have reported, among the potential beneficial effects in adults, a lower risk of dementia and cognitive decline with a higher intake of EPA plus DHA, although results from clinical studies are far less consistent (1).…”

Maternal Knowledge, Attitudes and Practices Regarding Dietary Fats

“…Finally, while the deficiency of alpha-linolenic acid has been linked to neurological abnormalities and poor growth, an optimal consumption of docosahexaenoic acid, the predominant omega-3 polyunsaturated fatty acid found in the brain, has been positively associated with beneficial effects on brain development during childhood and cognitive performance in the adult life [16,17].…”