Summary: Adolescents with higher blood levels of omega-3 fatty acids—particularly DHA—had a lower risk of developing psychotic disorder by their mid-twenties. At age 24, people with psychosis showed lower DHA levels than those without the disorder.
Source: RCSI
New research indicates that higher concentrations of certain omega-3 fatty acids in adolescence may reduce the likelihood of developing psychotic disorder in early adulthood, pointing to a possible preventive role for dietary omega-3s.
The study was led by researchers at RCSI University of Medicine and Health Sciences and appears in the journal Translational Psychiatry.
Researchers analyzed data from more than 3,800 participants enrolled in the well-established Children of the 90s cohort based in Bristol. Participants were assessed for psychotic disorder, moderate to severe depressive disorder, and generalized anxiety disorder (GAD) at around ages 17 and 24. Blood samples were taken at both occasions to measure levels of plasma polyunsaturated fatty acids (PUFAs).
Measurements focused on total omega-6 (n-6), total omega-3 (n-3), the n-6:n-3 ratio, and the percentage of docosahexaenoic acid (DHA) among total fatty acids. Omega-6 fatty acids are generally linked to pro-inflammatory processes, while omega-3 fatty acids are associated with anti-inflammatory effects and important neurodevelopmental functions.
At age 17, the team found little evidence of a relationship between PUFA levels and mental health diagnoses. By age 24, however, individuals diagnosed with psychotic disorder, depressive disorder, or GAD tended to have a higher omega-6 to omega-3 ratio than those without these conditions. Notably, those with psychotic disorder had significantly lower DHA percentages compared with peers without psychosis.
In longitudinal analyses of a subgroup of more than 2,700 people who were followed from 17 to 24 years, higher DHA levels at age 17 were associated with a substantially lower risk of developing psychotic disorder seven years later. Specifically, adolescents with elevated DHA showed an approximately 56% reduced odds of incident psychosis by age 24 after accounting for potential confounders.
The observed associations persisted after adjusting for sex, body mass index (BMI), tobacco smoking and socioeconomic status, strengthening the likelihood that the relationship between DHA and psychosis risk is not explained by these other factors.
“These findings require replication, but if confirmed, they suggest that increasing intake of omega-3–rich foods during adolescence—such as oily fish—could help prevent some cases of psychosis in early adulthood,” said Professor David Cotter, senior author and professor of molecular psychiatry at RCSI.
The results also raise questions about how elevated omega-6 levels may relate to emerging mental health disorders, given the different inflammatory profiles of omega-6 and omega-3 fatty acids and their varying roles in brain development.
The first author, Dr. David Mongan, an RCSI Ph.D. student and psychiatry trainee, led the data analysis under the supervision of Professor David Cotter and Professor Mary Cannon from the Department of Psychiatry at RCSI. The research team noted that further work is needed to identify the biological mechanisms that could explain the protective association, including potential effects on inflammation or on synaptic pruning during adolescence.
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Source: RCSI
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Original Research: Open access. “Plasma polyunsaturated fatty acids and mental disorders in adolescence and early adulthood: cross-sectional and longitudinal associations in a general population cohort” by David Mongan et al., Translational Psychiatry.
Abstract
Plasma polyunsaturated fatty acids and mental disorders in adolescence and early adulthood: cross-sectional and longitudinal associations in a general population cohort
Polyunsaturated fatty acids (PUFAs) could be relevant to the development of mental disorders through effects on inflammation and synaptogenesis. This study examined cross-sectional and longitudinal associations between plasma PUFA measures and mental disorders in a large cohort of young people.
Participants in the Avon Longitudinal Study of Parents and Children provided blood samples and underwent interviews at approximately 17 and 24 years of age. Plasma PUFA measures (total omega-6, total omega-3, the n-6:n-3 ratio, and DHA as a percentage of total fatty acids) were quantified using nuclear magnetic resonance spectroscopy.
Logistic regression models, adjusting for age, sex, BMI and cigarette smoking, assessed associations between standardized PUFA measures and three clinical outcomes: psychotic disorder, moderate to severe depressive disorder, and generalized anxiety disorder (GAD).
There was limited evidence of cross-sectional associations at age 17. By age 24, a higher n-6:n-3 ratio was positively associated with psychotic disorder, depressive disorder and GAD, while DHA was inversely associated with psychotic disorder.
Longitudinal analyses showed an inverse association between DHA at age 17 and incident psychotic disorder at age 24 (adjusted odds ratio 0.44, 95% confidence interval 0.22–0.87). Little evidence supported longitudinal associations between PUFAs and incident depressive disorder or GAD, and changes in PUFA measures from 17 to 24 showed minimal association with new onset disorders.
These findings support a link between PUFA profiles and mental disorders in early adulthood, and particularly suggest that higher DHA during adolescence may be associated with lower risk of developing psychosis.