ABSTRACT
Background: Mental health problems are increasingly prevalent among children and adolescents. Children from low income families are likely to have worse mental health than their wealthier peers. Understanding the association between economic deprivation and poor child mental health, how it varies across ages from early childhood to teen years, and the mechanisms underlying the association is of paramount importance to tackle this increasing public health problem which has been further exacerbated by the COVID-19 pandemic. Aim: This study aims to investigate the relationship between family income and child mental health problems from childhood to adolescence in the UK, its potential variation with age, and the potential mechanisms that may explain the relationship. Methods: Using data from the UK Millennium Cohort Study, child mental health was measured by the Total Difficulties Score (TDS), Internalising and Externalising subscales, all derived from the Strengths and Difficulties Questionnaire (SDQ) at ages 3, 5, 7, 11 and 14 years. Family income was operationalised as permanent income, with lagged transitory income used as robustness check. A secondary exposure was frequency of poverty. Cross-sectional analysis using multivariable logistic regression was conducted at each survey age, based on the Grossman health production function. Results: Results were available for 8,096 children, the prevalence of mental health problems (TDS) ranged from 4.6% to 11.1% across all ages. Unadjusted results indicated significant protective effects of higher family income on the likelihood of the child having poorer mental health in all age groups. The relationship weakened after adjustment for confounding and potential mediating factors, and marginal effects of income on TDS were -0.024(SE=0.009), -0.014(SE=0.004), -0.009(SE=0.006), -0.048(SE=0.010) and -0.041(SE=0.011) at age 3, 5, 7, 11, and 14 years, respectively (p<0.001 in all age groups except age 7 where p=0.163). Adjust- ment for poor maternal mental health and low mother-to-infant attachment reduced the strength of the association between income and child mental health. Fully adjusted model suggested an increased independent effect of poor maternal mental health on children's mental health as children grew older. Discussion: While family income is strongly associated with a child's mental health, much of this effect is explained by other risk factors such as maternal depression, and therefore the direct effects are relatively small. This may suggest that policies targeting income redistribution may reduce child mental health inequalities, and also be beneficial to the wider family, reducing the prevalence of other associated risk factors. This is even more important as the ongoing COVID-19 pandemic pushes more families into poverty.