Study: Low levels of omega-3 associated with higher risk of psychosis

06-Jul-2021 - Last updated on 06-Jul-2021 at 16:52 GMT

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Because depression appears less common in nations where people eat large amounts of fish, scientists have looked into whether fish oils may play a role in mood disorders over the years. Two omega-3 fatty acids —eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) —are thought to have the most potential to benefit people with mood disorders.

New research from RCSI University of Medicine and Health Science has found that adolescents with higher levels of an omega-3 fatty acid in their blood are less likely to develop psychotic disorders in early adulthood.

According to the researchers, polyunsaturated fatty acids (PUFAs) may be linked to the development of mental disorders. With this in mind, they examined the cross-sectional and longitudinal associations between PUFAs and mental disorders in a large cohort of young people.

The study

The study, published in Translational Psychiatry, examined over 3,800 individuals in Bristol's Children of the 90s health study and assessed them for psychotic disorder, depressive disorder and generalized anxiety disorder at age 17 and then again at age 24.

The researchers collected blood samples and measured omega-6 fatty acid levels, which typically increase inflammation in the body, and omega-3 fatty acids, which typically reduce inflammation.

“Humans may have evolved on a diet with a relatively balanced ratio of n-6:n-3 PUFAs, but in the average modern Western diet this ratio may be 10:1 or higher. Given the broadly opposing pro- and anti-inflammatory effects of their lipid mediators, the balance of n-6 and n-3 fatty acids is thought to be relevant to disease states characterized by inflammation such as cardiovascular disease. There is a body of evidence implicating low-grade inflammation in association with the presence or risk of mental disorders such as schizophrenia and depression, at least in a subset of affected patients. The precise biological mechanisms by which inflammation may contribute to the development of mental disorders are complex, but may include modulation of hypothalamic-pituitary-adrenal axis activity, neurotransmission, neurodegeneration and microglial activation. A lower ratio of n-6 to n-3 fatty acids may be associated with reduction in inflammation and thus presents one possible mechanism by which dietary factors can modulate inflammatory processes,” the authors explained.

Findings

While there was little evidence suggesting that fatty acids were associated with mental disorders at age 17, the researchers found that 24-year-olds with psychotic disorder, depressive disorder and generalized anxiety disorder had higher levels of omega-6 than omega-3 fatty acids compared to those without these mental disorders.

Additionally, 24-year-olds with psychotic disorder had lower levels of DHA than 24-year-olds without psychotic disorder. In a group of over 2,700 individuals who were tracked over time, adolescents with higher levels of DHA at age 17 were 56% less likely to develop psychotic disorder seven years later—suggesting that DHA in adolescence may play a potential role in reducing risk of psychosis in early adulthood.

"We need to do more research to learn about the mechanisms behind this effect, but it could possibly be related to reducing inflammation or decreasing inappropriate pruning of brain connections during adolescence," said David Mongan, the first author on the study.

Reaction

"While I should resist the urge to speculate, given that EPA data were not available to include in the present analysis, I suspect the mental health benefits, particularly for depression, may be underreported,” said Harry B. Rice, PhD, vice president of regulatory and scientific affairs for the Global Organization for EPA and DHA Omega-3s (GOED). “Of course, you can only work with the data you have and the present results provide reason enough for young adults to increase omega-3 intake.”

Indeed, the National Alliance on Mental Illness (NAMI) points out that mental illness is more prevalent than many may believe. “Psychosis is a symptom, not an illness, and it is more common than you may think. In the US, approximately 100,000 young people experience psychosis each year. As many as 3 in 100 people will have an episode at some point in their lives,” noted NAMI.

"The study needs to be replicated, but if the findings are consistent, these results would suggest that enhanced dietary intake of omega-3 fatty acids among adolescents, such as through oily fish like mackerel, could prevent some people from developing psychosis in their early twenties," said Professor David Cotter, senior author of the study and professor molecular psychiatry at RCSI. "The results could also raise questions about the relationship between the development of mental health disorders and omega-6 fatty acids, which are typically found in vegetable oils."

Source: Translational Psychiatry

11, 321 (2021) doi.org/10.1038/s41398-021-01425-4

“Plasma polyunsaturated fatty acids and mental disorders in adolescence and early adulthood: cross-sectional and longitudinal associations in a general population cohort”
Authors: D. Mongan et al.