Low birth weight and features of neuroticism and mood disorder in 83 545 participants of the UK Biobank cohort

Abstract

Background: Low birth weight has been inconsistently associated with risk of developing affective disorders, including major depressive disorder (MDD). To date, studies investigating possible associations between birth weight and bipolar disorder (BD), or personality traits known to predispose to affective disorders such as neuroticism, have not been conducted in large cohorts.

Aims: To assess whether very low birth weight (<1500 g) and low birth weight (1500-2490 g) were associated with higher neuroticism scores assessed in middle age, and lifetime history of either MDD or BD. We controlled for possible confounding factors.

Method: Retrospective cohort study using baseline data on the 83 545 UK Biobank participants with detailed mental health and birth weight data. Main outcomes were prevalent MDD and BD, and neuroticism assessed using the Eysenck Personality Inventory Neuroticism scale - Revised (EPIN-R).

Results: Referent to normal birth weight, very low/low birth weight were associated with higher neuroticism scores, increased MDD and BD. The associations between birth weight category and MDD were partially mediated by higher neuroticism.

Conclusions: These findings suggest that intrauterine programming may play a role in lifetime vulnerability to affective disorders.

Declaration of interest: None.

Copyright and usage: © The Royal College of Psychiatrists 2016. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) licence.

Fig. 1. Relative risk ratios and 95% confidence intervals for very low/low birth weight groups (v. normal weight) and probable major depressive disorder. Normal birth weight group = referent y-axis line.

(a) Unadjusted. (b) Adjusted for year of birth, Townsend deprivation score, ethnicity, gender, maternal smoking and maternal depression (i.e. covariates). (c) Additionally adjusted for hypertension, heart/cardiac problems, stroke, perivascular disease, type-2 diabetes, chronic obstructive pulmonary disease and osteoporosis (i.e. physical disease mediators).

Fig. 2. Three-way associations between low/very low birth weight (v. normal weight), neuroticism and probable major depressive disorder.

Values in brackets are relative risk (RR) ratio statistics, before controlling for neuroticism scores. ***P<0.001, **P<0.01. b = unstandardised beta coefficient. Adjusted RR = neuroticism scores included the model. A full description of the mediation process is provided by Preacher & Hayes.