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High childhood protein levels increased risk for adulthood depression, psychosis

There is a greater risk of developing depression and psychosis in adulthood among children with high daily protein levels, such as those released into the blood during an infection, according to recent study results published in JAMA Psychiatry.

“Our immune system acts like a thermostat, turned down low most of the time, but cranked up when we have an infection,” Golam M. Khandaker, PhD, of the department of psychiatry at the University of Cambridge, said in a press release. “In some people, the thermostat is always set slightly higher, behaving as if they have a persistent low level infection — these people appear to be at a higher risk of developing depression and psychosis. It’s too early to say whether this association is causal, and we are carrying out additional studies to examine this association further.”

Golam M. Khandaker

Khandaker and colleagues evaluated 4,500 people who had blood samples taken at age 9 years to determine the effect of serum levels of interleukin-6 (IL-6) on the risk for adulthood depression and psychosis. Depression and psychosis was examined at age 18 years. Participants were divided into three groups: high, medium and low levels of IL-6.

At follow-up, 17.2% of participants had depression as defined by the Clinical Interview Schedule-Revised (CIS-R). Four percent of participants reported psychotic experiences and 1.4% had a psychotic disorder as defined by CIS-R.

Compared with participants in the low level group, participants in the high level group were nearly two times more likely to have depression or psychosis at age 18 years.

“Our study provides evidence for a longitudinal association between a circulating inflammatory marker in childhood and future risks for depression and psychosis,” the researchers wrote. “Inflammatory pathways may provide important new prevention and intervention targets for major mental illnesses while also undermining the unhelpfully persistent Cartesian division between the mind and body.”

Disclosure: See the full study for a complete list of the researchers’ financial disclosures.