Several studies in the literature have reported associations between individual nutrient and food intakes and the prevalence of depression. However, the directions of effects are inconsistent. Studying foods or nutrients alone can be problematic due to the inter-correlations between them and their interactive effects. The use of dietary patterns enables the study of the whole diet by reducing a large number of food intake variables into a handful of variables which best describe the overall dietary types in a population. Dietary patterns have already been obtained in both the ALSPAC mothers and their partners when their study child was 47 months of age (Northstone & Emmett, 2010).

A small number of studies have examined cross-sectional associations between dietary patterns and depression in diverse populations. A Japanese study found a protective effect of a 'healthy' dietary pattern (high intakes of fruit, veg, soy products) and depressive symptoms (Nanri et al, 2010). Similar associations were seen in a French elderly population (Samieri et al, 2008) and in a UK sample of middle-aged adults (Akbaraly et al, 2009) whereby a 'healthy' pattern was associated with a reduced risk of depression. Finally Oddy et al (2009) reported poorer mental health in Australian adolescents who scored higher on a 'Western' pattern (high in red/processed meats, confectionery and refined foods).

However, all these studies are limited by their cross-sectional nature and the alternative explanation of reverse causality cannot be excluded. In other words it is possible that the presence of depression in individuals may cause them to alter the way in which they eat (possibly in order to enhance mood or because when depressed individuals turn to 'easy'foods).

To overcome this limitation, we propose taking a 'disease-free' cohort of men and women based on EPDS scores recorded when the study child was 33 months of age. That is, selecting those who are not depressed at baseline (EPDS score less than 13). We will then examine the effect of dietary patterns obtained at 47 months on depression assessed at 61 months (in men and women separately).

A large number of confounders will be considered including age, ethnicity, education, employment, marital status, physical activity, smoking, alcohol intake, energy intake and health status.

This project will feed into further work where we propose to examine the effects of diet on mental health in adolescents, subject to funding.

References

Akbaraly TN, Brunner EJ, Ferrie JE, Marmot MG, Kivimaki M, Singh-Manoux A. Dietary pattern and depressive symptoms in middle age. Br J Psychiatry 2009; 195: 408-413.

Nanri A, Kimura Y, Matsushita Y, Ohta M, Mishima N, Sasaki S, Mizoue T. Dietary patterns and depressive symptoms among Japanese men and women. Eur J Clin Nutr 2010; 64: 832-839.

Northstone K, Emmett PM. Dietary patterns of men in ALSPAC: associations with socio-demographic and lifestyle characteristics, nutrient intake and comparison with women's dietary patterns. Eur J Clin Nutr 2010; 64: 978-986.

Oddy WH, Robinson M, Ambrosini GL, O'Sullivan TA, de Klerk NH, Beilin LJ, Silburn SR, Zubrick SR, Stanley FJ. The association between dietary patterns and mental health in Australian adolescence. Preventive Medicine 2009; 49: 39-44.

Samieri C, Jutand M-A, Feart C, Barberger-Gateau P. Dietary patterns derived by hybrid clustering method in older people: Association with cognition, mood and self-rated health. J Am Dietet Assoc 2008; 108: 1461-1471.