Omega-3 Improve Cognitive Abilities and Intelligence in Older Adults

Omega-3 fatty acids are essential for maintaining brain health and so-called fluid intelligence, which is the brain's ability to handle new situations independently of previously acquired knowledge. In particular, high concentrations of ALA (alpha-linolenic acid), SDA (stearidonic acid), and ETE (eicosatrienoic acid) are linked to better fluid intelligence and a greater volume of the brain region involved in this function, confirming that cognitive decline in older age also depends on nutritional status.

This was demonstrated by researchers at the University of Illinois Urbana-Champaign, in a study published recently in the journal Nutritional Neuroscience.

Omega-3 Protect Cognitive Abilities

A large body of scientific evidence shows that polyunsaturated fatty acids have protective effects on the brain during aging. In particular, omega-3s are known to be abundant in neuron membranes where they contribute to structural integrity, regulate membrane fluidity, and influence the production of neurotransmitters and neuropeptides, substances responsible for information transfer between nervous system cells. High omega-3 intake has been linked to better memory performance and a decreased risk of dementia in the elderly. 

Recent studies have also shown that decline in fluid intelligence, one of the most debilitating aspects of cognitive aging, is connected to blood omega-3 fatty acid levels. Fluid intelligence is the brain’s capacity to tackle new situations, distinct from crystallized intelligence, which is the collection of previously acquired knowledge and experience. Declining fluid intelligence indicates a reduced ability to acquire new skills and is due to deterioration of a neuron system that supports new learning. Fluid intelligence is linked to a particular brain area called the frontoparietal cortex (FPC). 

The relationship between cognitive abilities and levels of EPA and DHA omega-3s is well known, but few studies have investigated whether concentrations of their precursors and other omega-3s, such as ALA (alpha-linolenic acid), SDA (stearidonic acid), and ETE (eicosatrienoic acid), are involved in this protective effect. Similarly, EPA and DHA concentrations have been associated with better cognitive test performance in older adults, but other omega-3s have been less examined. Scientific evidence has revealed that plasma ALA levels are linked to dementia risk. Fluid intelligence decline is a key feature of cognitive changes preceding senile dementia, so ALA and its derivatives, including SDA and ETE, might serve as biomarkers of fluid intelligence status. Like EPA and DHA, SDA and ETE can be synthesized by the human body from alpha-linolenic acid.

Omega-3 ALA, ETE, and SDA Protect Fluid Intelligence

In this new study, researchers examined the link between maintaining cognitive abilities and omega-3s capable of acting on specific brain health aspects, such as the ability to acquire new knowledge and information. Analyses revealed that levels of alpha-linolenic acid, stearidonic acid, and eicosatrienoic acid were linked to fluid intelligence and total FPC volume, suggesting that these fatty acids help preserve this cognitive ability by maintaining the cerebral cortex structure in healthy older adults. These results suggest that some lesser-studied omega-3s have important effects on mental health, independent of their role in the pathway leading to EPA and DHA formation. ALA has traditionally been considered less influential due to its low ability to form EPA and DHA; its conversion rate is low and can be further reduced by high saturated fat intake, a common characteristic of Western diets. A 1998 Swiss study on this topic concluded that with a diet high in saturated fats, conversion of ALA to its derivatives is about 6% for EPA and 3.8% for DHA, and when omega-6 intake is also high, conversion decreases by 40-50%.

Some Details of the Study

During the research, U.S. scientists selected 122 cognitively healthy adults aged 65 to 75 years, of whom 100 participated in the study. Blood levels of various omega-3s were measured for each participant. Fluid intelligence and other abilities were estimated through specific cognitive tests. Brain cortex volume was assessed by magnetic resonance imaging. Through appropriate statistical analyses, all data were correlated taking into account age, sex, education, and body mass index of each subject. Results revealed that individuals with higher blood concentrations of ALA, SDA, and ETE scored better on cognitive tests and showed greater FPC volume, suggesting a link between these three parameters.

Results Open the Way for Further Research

According to the researchers, the findings identify some omega-3s related to cognitive abilities and a new relationship between these, brain structure, and fluid intelligence. Future investigations will need to determine whether the molecules are neuroprotective themselves or whether their elevated levels indicate greater conversion toward EPA and DHA. Stearidonic acid, in fact, can convert into EPA more efficiently than ALA. In any case, the study results confirm that age-related cognitive decline is not only due to brain degeneration but also nutritional status; ALA, SDA, and ETE are fatty acids present in various animal (fish) and plant (oil seeds, nuts) foods.

Source: Zamroziewicz MK, Paul EJ, Zwilling CE, Barbey AK. “Determinants of fluid intelligence in healthy aging: Omega-3 polyunsaturated fatty acid status and frontoparietal cortex structure.” 2017 May 11:1-10. Nutritional Neuroscience.