A new study identified a dose-response association between longer amounts of time spent in low-income conditions during childhood and a higher risk of developing schizophrenia after age 15. Researchers published their findings online in JAMA Psychiatry.
“Cohort members from families in the lowest income quintile were more likely to be diagnosed with the disorder, even after adjustment for parental mental illness, degree of urbanization, parental educational attainment level, and number of changes in child-parent separation status,” researchers wrote.
The national cohort study included more than 1 million people born in Denmark between 1980 and 2000. Participants were followed from their 15th birthday until a diagnosis of schizophrenia, emigration, death, or the end of 2016.
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The study identified an inverse association between parental income level during childhood and schizophrenia risk after age 15, with children from lower-income families having the highest schizophrenia risk. Furthermore, researchers discovered, the longer the time children spent in low-income conditions, the higher their schizophrenia risk.
However, the study also found that upward income mobility was linked with a lower risk of schizophrenia compared with downward income mobility—regardless of parental income level at birth.
“For example, children who were born and remained in the lowest income quintile at age 15 years had a 4.12 (95% CI, 3.71-4.58) elevated risk compared with the reference group, those who were born in and remained in the most affluent quintile, but even a rise from the lowest income quintile at birth to second lowest at age 15 years appeared to lessen the risk elevation (HR, 2.80; 95% CI, 2.46-3.17),” researchers reported.
“On the contrary, for those born in the most affluent quintile, downward income mobility between birth and age 15 years was associated with increased risks of developing schizophrenia.”
Although causal mechanisms are unclear, enabling upward income mobility may help reduce schizophrenia incidence at the population level, researchers observed.
Hakulinen C, Webb RT, Pedersen CB, Agerbo E, Mok PLH. Association between parental income during childhood and risk of schizophrenia later in life. JAMA Psychiatry. 2019 October 23;[Epub ahead of print].