Cross-national comparisons of seafood consumption and rates of bipolar disorders.

OBJECTIVE: The authors sought to determine if greater seafood consumption, a measure of omega-3 fatty acid intake, is associated with lower prevalence rates of bipolar disorder in community samples.
METHOD: Lifetime prevalence rates in various countries for bipolar I disorder, bipolar II disorder, bipolar spectrum disorder, and schizophrenia were identified from population-based epidemiological studies that used similar methods. These epidemiological studies used structured diagnostic interviews with similar diagnostic criteria and were population based with large sample sizes. Simple linear and nonlinear regression analyses were used to compare these prevalence data to differences in apparent seafood consumption, an economic measure of disappearance of seafood from the economy.
RESULTS: Simple exponential decay regressions showed that greater seafood consumption predicted lower lifetime prevalence rates of bipolar I disorder, bipolar II disorder, and bipolar spectrum disorder. Bipolar II disorder and bipolar spectrum disorder had an apparent vulnerability threshold below 50 lb of seafood/person/year. The absence of a correlation between lifetime prevalence rates of schizophrenia and seafood consumption suggests a specificity to affective disorders.
CONCLUSIONS: These data describe a robust correlational relationship between greater seafood consumption and lower prevalence rates of bipolar disorders. These data provide a cross-national context for understanding ongoing clinical intervention trials of omega-3 fatty acids in bipolar disorders.