Alzheimer's disease: does fish oil slow neurodegenerative processes?

Omega 3 EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) taken with supplements can cross the blood-brain barrier in Alzheimer's patients, acting positively on neurodegenerative processes. Indeed, a high level of DHA corresponds to a change in markers of the disease and inflammation.

That's what researchers at Karolinska Institutet in Sweden found during a study investigating the effect of Omega-3 supplementation on the concentration of fatty acids in cerebrospinal fluid. The finding was published in the Journal of Internal Medicine.

Omega-3 and Alzheimer's disease

Omega-3s, especially DHA, are components of the membranes of neurons to which they confer stability, and ensure their proper growth and function. In addition, thanks to their anti-inflammatory action, DHA and EPA defend the nervous system against cognitive decline and other diseases In this regard, several studies have shown how Omega-3s can protect against Alzheimer's by reducing the risk of developing the disease. In fact, other work has shown that many neuropathies can affect the fatty acid profile of the central nervous system (CNS). In the case of Alzheimer's, a lower than normal concentration of DHA has been observed. Omega-3 and other polyunsaturated fatty acids are accumulated in the CNS during gestation, and are then, throughout life, continuously replaced. However, it is not yet well understood how this mechanism occurs, and whether variations in diet can affect the passage of Omega-3s across the blood-brain barrier. The latter is a structure interposed between the blood and CNS that selectively regulates the passage of chemicals to and from the brain, protecting the nervous system. However, it also blocks the passage of drugs In light of this knowledge, the researchers, who conducted the study, attempted to understand what was the effect of Omega-3 supplementation in patients who had already developed Alzheimer's disease

The action of DHA on disease markers.

The research, carried out as part of a larger project, involved 33 Alzheimer's patients. For 6 months, 18 of them received a 2.3-gram supplement of Omega-3 (rich in DHA) every day without knowing its content, while the other 15 participants were given a placebo. After treatment, the concentrations of DHA and EPA, in plasma and in cerebrospinal fluid surrounding the CNS, were assessed. These analyses revealed that in the subjects who had received the supplement, plasma and cerebrospinal fluid Omega-3 levels were increased, whereas in the placebo group no such changes were evident. In addition, DHA values were related to the course of Alzheimer's disease and to markers of the disease.. In cerebrospinal fluid, in fact, the level of DHA was inversely related to the concentration of hyperphosphorylated Tau protein, a marker of Alzheimer''s, and directly related to the levels of the soluble receptor for interleukin 1, a molecule involved in inflammatory processes.

Omega-3s reach the central nervous system

Based on this evidence, the researchers hypothesized that Omega-3s can cross the blood-brain barrier by reaching the nervous system and affecting its fatty acid composition, as had been observed in previous animal studies, in which supplementation with DHA corresponded to a higher concentration of the molecule in the CNS. In addition, the increase of DHA in the CNS corresponds to a strong change in biomarkers typical of the disease and inflammatory state. The study therefore confirms the link between Alzheimer's disease and inflammation. Treatments with traditional anti-inflammatories, used so far, however, have proven ineffective in improving symptoms. More studies will therefore be needed to understand how Omega-3s can be used to treat the disease and halt the memory loss that plagues Alzheimer's patients.

Source: Y. Freund Levi, I. Vedin, T. ^Cederholm4, H. ^Basun5, G. Faxén Irving, M. Eriksdotter, E. Hjorth, M. Schultzberg, B. Vessby, L.-O. Wahlund, N. Salem Jr, J. Palmblad. "Transfer of omega-3 fatty acids across the blood-brain barrier after dietary supplementation with a docosahexaenoic acid-rich omega-3 fatty acid preparation in patients with Alzheimer's disease: the OmegAD study" Journal of Internal Medicine. Article first published online: 11 JAN 2014 DOI: 10.1111/joim.12166.