Childhood inflammation linked to higher risk of mental health disorders in adulthood

A recent study published in JAMA Psychiatry has found that children who experience persistently high levels of inflammation are more likely to face serious mental health challenges, such as depression and psychosis, as they reach early adulthood. The research also indicates that these individuals are at an increased risk of developing cardiometabolic conditions, including insulin resistance, a precursor to diabetes. The study sheds new light on the long-term impact of chronic inflammation during childhood and adolescence and suggests that inflammation could be a key factor in both mental and physical health risks later in life.

Mental health and physical health conditions, particularly cardiometabolic diseases like diabetes and heart disease, are two of the biggest health concerns worldwide. Many studies have shown a connection between chronic inflammation and mental health conditions, such as depression, anxiety, and psychosis. Inflammation is the body’s immune response to threats like infections or injuries, but when this response becomes prolonged, it can contribute to various health problems.

Previous research has mostly looked at inflammation at a single point in time, which doesn’t capture how inflammation levels might change over a person’s life. In addition, most studies have focused on either mental health or physical health outcomes, not both. This new study aimed to fill those gaps by tracking inflammation over multiple points during childhood and adolescence, then looking at its links to both mental and cardiometabolic health in early adulthood.

The researchers hypothesized that children with chronically elevated inflammation would have higher risks for developing both mental health issues and cardiometabolic disorders. Specifically, they expected to see stronger links between inflammation and conditions like psychosis, depression, and insulin resistance, which is often a precursor to type 2 diabetes.

“For some time, there has been an interest in whether inflammation could play a role in mental health disorders. To help understand this association, we wanted to conduct a study that could allow us to examine the degree and pattern of inflammation well before the onset of mental health disorder,” said study author Edward Palmer, an academic clinical fellow and PhD student at the University of Birmingham.

The research team used data from the Avon Longitudinal Study of Parents and Children (ALSPAC), a long-term study based in the United Kingdom that began in the early 1990s. This study tracks the health and development of children from birth into adulthood. For this particular research, the scientists analyzed data from over 6,500 participants.

The researchers measured levels of C-reactive protein (CRP), a marker of inflammation, at three points in the children’s lives—ages 9, 15, and 17. CRP is often used in medical settings to assess inflammation, as higher levels usually indicate a heightened immune response. The researchers then classified the participants into different groups based on how their CRP levels changed over time.

Next, they examined whether these different inflammation patterns were linked to mental health outcomes at age 24, including psychotic experiences, clinical depression, and anxiety. They also looked at cardiometabolic health by measuring insulin resistance at age 24. To make sure their results were as accurate as possible, the researchers accounted for other factors that could influence health outcomes, such as body weight, birth complications, and early childhood health issues.

The researchers identified three distinct groups based on inflammation patterns. The largest group, making up about 93 percent of the participants, had consistently low levels of inflammation throughout childhood and adolescence. Two smaller groups had persistently elevated inflammation, but the timing of their inflammation spikes differed. One group, about 3 percent of the participants, had an early peak in inflammation at age 9, followed by a gradual decrease. The other group, around 4 percent, had a later peak in inflammation around age 17.

The early-peak group (those with higher inflammation levels at age 9) had a significantly higher risk of developing psychotic disorders, such as schizophrenia, by age 24. They were also more likely to experience severe depression. The late-peak group, on the other hand, did not show strong associations with mental health problems.

“The study demonstrates that low-grade information is associated with both mental health and cardiometabolic disorders,” Palmer told PsyPost.

Both groups with elevated inflammation had a higher likelihood of developing insulin resistance by age 24, suggesting that childhood inflammation might be linked not only to mental health disorders but also to physical health problems like diabetes.

The study provides important insights into the links between childhood inflammation and health outcomes in adulthood. But the study, like all research, has some limitations. For one, the researchers were not able to measure inflammation before age 9, meaning they may have missed earlier periods of high inflammation that could also be important.

There is still much to learn about the exact relationship between inflammation and mental and physical health. While this study suggests that inflammation could be a common factor in the development of both mental illness and cardiometabolic disorders, it doesn’t prove that inflammation causes these conditions.

“We have not proven a causal link between inflammation and these disorders, more work is needed to demonstrate causality, and further understand this association and the biological or other mechanism behind it,” Palmer said.

Future studies could explore why some children have persistently high inflammation while others do not. Factors such as genetics, early-life infections, or exposure to stress and adversity might all play a role, but the current study did not investigate these possibilities. Identifying these factors could be a key step toward preventing inflammation-related health problems later in life.

This study is part of a growing body of research that suggests inflammation could play a significant role in both mental and physical health. If future studies confirm that inflammation is a key contributor to conditions like depression, psychosis, and diabetes, it could open up new possibilities for prevention and treatment. For instance, doctors might one day be able to use inflammation markers like CRP to identify children at high risk of mental illness or cardiometabolic disease, allowing for earlier interventions.

“With more work understanding the risk factors that predispose people to mental illness, our hope is that one day we may be able to use inflammation as a way of risk profiling people for mental illness,” Palmer explained. “This would allow us to concentrate interventions on those at highest risk and attempt to prevent illness developing. If we can prove inflammation plays a causal role, and understand the mechanism behind this, we may be able to use inflammation as a new treatment target in either treatment or prevention. Our research group is already investigating the potential therapeutic role of anti-inflammatories.”

The study, “Trajectories of Inflammation in Youth and Risk of Mental and Cardiometabolic Disorders in Adulthood,” was authored by Edward R. Palmer, Isabel Morales-Muñoz, Benjamin I. Perry, Steven Marwaha, Ella Warwick, Jack C. Rogers, and Rachel Upthegrove.