Associations between diet quality and DSM-IV mood disorders during young- to mid-adulthood among an Australian cohort.

PURPOSE: Many studies have reported associations between diet and depression, but few have used formal diagnoses of mood disorder as the outcome measure. We examined if overall diet quality was associated cross-sectionally or longitudinally with DSM-IV mood disorders among an adult cohort. METHODS: Participants from the Australian Childhood Determinants of Adult Health study were followed up during 2004-06 (n = 1974, age 26-36 years), 2009-11 (n = 1480, 31-41 years), and 2014-19 (n = 1191, 36-49 years). Dietary Guidelines Index (DGI) scores were calculated from food frequency questionnaires at each time-point (higher DGI reflects better diet quality). DSM-IV mood disorders (dysthymia or depression) during the periods between, and 12 months prior to each follow-up were determined using the Composite International Diagnostic Interview. Sex-stratified risk and prevalence ratios (PR) and 95% confidence intervals (CI) were estimated using log-binomial regression. Covariates included age, self-perceived social support index score, marital status, parenting status, education, occupation, physical activity, BMI, and usual sleep duration. RESULTS: A 10-point higher DGI was cross-sectionally associated with lower prevalence of mood disorders at the third follow-up only (females PR = 0.73, 95% CI = 0.56, 0.95; males PR = 0.72, 95% CI = 0.53, 0.97), but was attenuated after covariate adjustment (females PR = 0.92, 95% CI = 0.73, 1.16; males PR = 0.92, 95% CI = 0.69, 1.22). Adjustment for social support in the final model had attenuated the association for both sexes from 18% reduced prevalence to 8%. DGI scores were not longitudinally associated with mood disorder risk. CONCLUSIONS: Crude cross-sectional associations between diet quality and mood disorders at ages 36-49 years were explained by sociodemographic and lifestyle factors, particularly social support.

Associations between childhood to adulthood socio-economic mobility and adult diet quality.

The impact of change in socio-economic status (SES) from childhood to adulthood (SES mobility) on adult diet is not well understood. This study examined associations between three SES mobility variables (area disadvantage, education, occupation) and adult diet quality. 1482 Australian participants reported childhood area-level SES in 1985 (aged 10-15 years) and retrospectively reported highest parental education and main occupation (until participant age 12) and own area-level SES, education, occupation and dietary intake in 2004-2006 (aged 26-36 years). A Dietary Guidelines Index (DGI) was calculated from food frequency and habit questionnaires. A higher score (range 0-100) indicated better diet quality. Sex-stratified linear regression models adjusted for confounders. Area-level SES mobility was not associated with diet quality. Compared with stable high (university) education, stable low (school only) was associated with lower DGI scores (males: ß = -5·5, 95 % CI: -8·9, -2·1; females: ß = -6·3, 95 % CI: -9·3, -3·4), as was downward educational mobility (participant's education lower than their parents) (males: ß = -5·3, 95 % CI: -8·5, -2·0; females: ß = -4·5, 95 % CI: -7·2, -1·7) and stable intermediate (vocational) education among males (ß = -3·9, 95 % CI: -7·0, -0·7). Compared with stable high (professional/managerial) occupation, stable low (manual/out of workforce) males (ß = -4·9, 95 % CI: -7·6, -2·2), and participants with downward occupation mobility (males: ß = -3·2, 95 % CI: -5·3, -1·1; females: ß = -2·8, 95 % CI: -4·8, -0·8) had lower DGI scores. In this cohort, intergenerational low education and occupation, and downward educational and occupational mobility, were associated with poor adult diet quality.

An age- and sex-specific dietary guidelines index is a valid measure of diet quality in an Australian cohort during youth and adulthood.

Measuring diet quality over time is important due to health impacts, but to our knowledge, a Dietary Guidelines Index (DGI) with consistent scoring across childhood/adolescence (youth) and adulthood has not been validated. We hypothesized that a DGI that reflected age- and sex-specific guidelines would be a valid measure of diet quality in youth and adulthood. The DGI is based on the 2013 Australian Dietary Guidelines to reflect current understanding of diet quality and comprises 9 indicators, with a maximum score of 100 points. DGI scores were calculated for participants of the Australian Childhood Determinants of Adult Health study, which included a 24-hour food record during youth (1985, n = 5043, age: 10-15 years) and a 127-item food frequency questionnaire during adulthood (2004-2006, n = 2689, age: 26-36 years). We evaluated construct validity (distribution of scores, principal components analysis, correlation with nutrient density of intakes) and criterion validity (linear regression with population characteristics). DGI scores were multidimensional in underlying structure and normally distributed. Among youth, a lower DGI was significantly associated (P < .05) with smoking and with lower academic achievement and socioeconomic status. DGI scores were negatively correlated with energy, sugar, and fat and positively correlated with fiber, protein, and micronutrients. Among adults, a lower DGI was associated with lower education and self-reported health and higher waist circumference, insulin resistance, and total and low-density lipoprotein serum cholesterol. The DGI is an appropriate measure of diet quality in youth and adulthood because higher scores reflect nutrient-dense, rather than energy-dense, intake and discriminate between population characteristics consistent with the literature.