How poverty and mental health problems are passed down in Norway
Children are more likely to have mental health problems when their parents earn less. Why is this?
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The more parents earn, the better their children's mental health. Compared to the wealthiest families, three times as many sons of low-income parents have a mental health problem.
How is children's mental health actually related to parental income?
Researchers at the Norwegian Institute of Public Health (NIPH) have explored this question.
Boys with behavioural problems, girls with anxiety
Researchers studied mental health problems in children aged 5 to 17 and compared these with parental income.
In childhood, boys are most vulnerable to growing up in families with financial difficulties. As many as 15 per cent of boys in low-income families have mental health problems, while the proportion is less than 5 per cent among the wealthy.
Among boys, behavioural disorders such as ADHD, difficulties with social functioning, and attachment problems are the most common.
Before puberty, girls have fewer mental health problems but follow a similar pattern. Girls are more prone to anxiety and depression.
10 per cent of girls in the lowest-income families have mental health problems, compared to only 3 per cent in wealthy families.
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"There's a clear effect of parental income in adolescence. This diminishes as the adolescents grow into adults," says researcher Fartein Ask Torvik at NIPH.
Parental mental health influences the level of education they attain.
This, in turn, affects how much they earn, which impacts their children's mental health and education.
"Certain mental health problems affect school performance, which then impacts educational paths," says researcher Magnus Nordmo at NIPH.
Diagnoses doubled in the last 13 years
ADHD is the most common diagnosis among boys. 14.6 per cent of boys have the diagnosis, compared to 7.5 per cent of girls. However, researchers do not believe this is the main reason boys perform worse in school.
Anxiety and depression also contribute to weakening school performance. However, it is difficult to research diagnoses and academic performance and determine what influences what.
Between 2006 and 2019, ADHD diagnoses more than doubled for boys and increased even more for girls. Anxiety and depression have also doubled among girls and risen significantly among boys.
Despite this, fewer children perform poorly in school. Those with diagnoses today do not perform as poorly as before. This could be due to better medications or improved accommodations at school.
Torvik at NIPH explains that it seems good schools manage to ensure that genes no longer have as much influence on the children's grades.
Parents with mental health problems
Why do children of low-income parents more often have mental health problems? Lack of money itself is not the cause; low-income families often face other challenges.
When researchers examined the issue more closely, they found that children of parents with mental health problems are most at risk of receiving mental health diagnoses themselves.
Additionally, twice as many of these children are diagnosed with mental health problems if they grow up in a low-income family compared to a healthy family.
Twice as many children of single low-income parents have mental health problems compared to those with two low-income parents.
Researchers also found that children of parents with low education and income are more likely to have mental health problems than children of low-income parents with higher education. Education provides a protective effect, even without high income.
Mental health problems correlate with IQ
Academic performance is linked to what researchers refer to as conscientiousness – that is, being tidy and organised.
However, cognitive abilities also play a significant role. These include memory, comprehension, and problem-solving. Many of these skills are genetic, meaning they are largely inherited from your parents.
Researchers examined the IQ of 18-year-old men born between 1970 and 1979, measured during military conscription. IQ was scored on a scale from 1 to 9, with 9 being the highest IQ. They then tracked how many of these individuals had mental health problems betweent the ages of 35 and 40.
Mental health problems are linked to IQ. 30 per cent of men with low IQs had mental health problems, compared to only 10 per cent of those with the highest IQs.
These findings remain consistent even after adjusting for social background. Mental health problems such as substance and alcohol abuse had the strongest association. The group most affected had low education levels and scored poorly on cognitive skills.
Researchers refer to this as the reproduction of mental health and social inequality. This means poverty – and wealth – are often inherited.
"We also tend to choose partners similar to ourselves, which amplifies weaknesses and strengths in children," says Torvik.
Adoption studies
To explore how genetics and inheritance influence life outcomes, researchers at the Norwegian Institute of Public Health conducted various familial studies, including twin and cousin studies.
They also conducted adoption studies, where there were no genetic links between parents and children.
In adoption cases, they found very different results for internationally adopted children compared to those born in Norway. The prevalence of anxiety among adopted children, for example, is not linked to how much their parents earn.
Genes matter twice as much as environment
Educated parents are better equipped to assist with homework, providing children with valuable support from their environment.
Despite this, researchers discovered that genes have twice the impact on academic skills compared to the level of education the parents have.
They also examined how parents' income and education affect children's mental health in adulthood. The researchers observed that parental income during adolescence has a significant impact. However, this influence decreases as the child grows older.
The researchers linked health service registry data for 1.3 million children with tax data and education records. The results were recently presented at the final seminar on Social inequality, mental health, and genetics at the Culture House in Oslo.
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Translated by Alette Bjordal Gjellesvik
Read the Norwegian version of this article on forskning.no
References:
Kinge et al. Association of Household Income with Life Expectancy and Cause-Specific Mortality in Norway 2005 - 2015, JAMA, 2019. DOI: 10.1001/jama.2019.4329
Kinge et al. Parental income and mental disorders in children and adolescents: prospective register-based study, International Journal of Epidemiology, vol. 50, 2021. DOI: 10.1093/ije/dyab066
Nordmo et al. The educational burden of disease: a cohort study, The Lancet Public Health, vol. 7, 2022. DOI: 10.1016/S2468-2667(22)00059-7
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