Low parental income associated with later risk for mental health conditions

Individuals born to parents in the lowest income quintile had higher risk for developing mental health conditions, including substance use and personality disorders, according to study results published in BMC Medicine.

“Our study demonstrated that the longer children grew up in families with low-income parents, the greater their risk was [for] developing a mental disorder," Christian Hakulinen, PhD, of the department of psychology and logopedics at the University of Helsinki in Finland, said in a press release.

Hakulinen and colleagues conducted a national cohort study of 1,051,265 people born between January 1980 and December 2000 whose parents were both Danish. They gathered data on parental income, place of residence and vital status from the Danish Civil Registration System. Researchers measured parental income quintiles at ages 5, 10 and 15 years and conducted follow-ups after age 15 years. The study’s outcome measure was diagnosis of a mental health condition before the data collection period ended, making the oldest age at follow-up 37 years.

People whose parents were in the lowest income quintile had a mental health condition diagnosis by age 37 years more frequently than those born in the highest quintile (25.5% vs. 13.5%). Length of time in lower income quintiles was associated with a greater risk for mental health condition diagnosis. People who were in the lowest quintile at birth and ages 5, 10 and 15 years had a 34.3% absolute risk (95% CI, 33.4-35.1) compared with a 12% absolute risk (95% CI, 11.5-12.5) among those in the highest quintile at birth and ages 5, 10 and 15 years.

The researchers wrote that the associations between low income and mental health condition diagnosis were strongest for substance use (HR = 3.44; 95% CI, 3.27-3.62) and personality disorders (HR = 2.76; 95% CI, 2.64-2.88). They also found associations for broadly defined schizophrenia (HR = 2.38; 95% CI, 2.25-2.50), mood disorders (HR = 1.72; 95% CI, 1.67-1.78) and anxiety or somatoform disorders (HR = 2.11; 95% CI, 2.06-2.17). Conversely, people born in the lowest quintile had a lower risk for diagnosis of an eating disorder (HR = .90; 95% CI, .85-.96). The researchers wrote that “[f]or all disorders, the associations were attenuated when adjusted for additional covariates, but risk gradients remained.”

“Measures focused on childhood, such as interventions in support of parenthood, could benefit low-income families in particular. This would make it possible to tackle psychosocial risk factors, which financial challenges typically aggravate,” Hakulinen said in the release.