Poverty and mental Illness: A causal relationship revealed

Poverty and mental illness are not only linked, but there is also a causal relationship. This is the conclusion of researchers from Amsterdam UMC, the University of Edinburgh and the University of Modena. Their study shows that while certain mental health issues can hinder financial stability, poverty is also one of the causal factors leading to mental health problems. This study was published today in Nature Human Behaviour. 

This study indicates that certain mental health problems can make a person's financial situation uncertain. But conversely, we also see that poverty can lead to mental health problems."

Marco Boks, psychiatrist at Amsterdam UMC 

Previous research has shown a strong correlation between poverty and mental illness, but disentanglement between cause and effect proved difficult. The consequences of mental illness can affect a person's financial situation, for example, if this person is unable to work as well or has higher healthcare costs. But difficult financial circumstances can also cause psychological problems. 

Complex relationship 

The researchers used data from the UK Biobank and the international Psychiatric Genomic Consortium. "We discovered that schizophrenia and ADHD causally contribute to poverty. Conversely, poverty contributes to major depressive disorder and schizophrenia. The risk of anorexia nervosa is actually reduced when there is poverty," says Boks. 

Firstly, a measure of poverty was determined on the basis of household income, occupational income and social deprivation. Researchers then used the participants' genetic information using a special technique called Mendelian randomization to untangle the relationship. Mendelian randomization is a method of determining the influence of risk factors on a disease, by measuring the variation of genes that are more common in certain traits. 

"We were able to capture aspects of poverty shared between the individual, the household, and the area in which one lives. This enabled us to better identify the causal effects of poverty on mental illness," says David Hill, statistical geneticist at the University of Edinburgh. 

Vicious circle

The findings of this research are important for policy and the approach to both poverty and mental illness. By recognizing the reciprocal influence between poverty and mental health, policymakers can develop more effective interventions aimed at breaking the cycle of poverty and mental health problems. "The research provides robust evidence for the need to also look at social factors such as poverty, when you delve into the development of mental illness," says Boks. 

"Our findings suggest that the reduction of inequalities could lead to substantial public mental health gain," adds Mattia Marchi, psychiatrist at the University of Modena. 

"There is often confusion about the use of genetic data to investigate the relationship between poverty and mental illness. We emphasize that this does not mean that poverty is genetic. On the contrary, with genetic data, we were able to identify poverty as a modifiable environmental factor for mental health," concludes Boks.