Diet quality in bipolar disorder in a population-based sample of women

Recent epidemiological evidence has indicated a role for diet quality in unipolar depressive illness. This study examined the association between diet quality and bipolar disorder (BD) in an epidemiological cohort of randomly selected, population-based women aged 20-93 years.

An a priori diet quality score was derived from food frequency questionnaire data, a factor analysis identified habitual dietary patterns and glycemic load was assessed. Mental health was assessed using the SCID-I/NP.

BD was identified in 23 women and there were 691 participants with no history of psychopathology. Compared to those with no psychopathology, those with BD had a higher glycemic load (p=0.06) and higher scores on a 'western' dietary factor (p=0.03) and the 'modern' dietary factor (p=0.02). For each standard deviation increase in a 'western' and 'modern' dietary pattern and glycemic load, the odds ratios for BD were increased ('western' OR=1.88, 95% CI 1.33-2.65; 'modern' OR=1.72, 95% CI 1.14-2.39; GL OR=1.56, 95% CI 1.13-2.14). Conversely, a 'traditional' dietary pattern was associated with reduced odds for BD (OR=0.53 95% CI 0.32-0.89) after adjustments for overall energy intake.

The small sample size did not allow for multivariate analyses and the cross-sectional study design precludes any determinations regarding the direction of the relationships between diet quality and BD.

These data are largely concordant with results from dietary studies in unipolar depression. However, clinical recommendations cannot be made until the direction of the relationship between diet quality and BD is determined. Longitudinal studies are warranted.