People who have mental illness are more likely to have higher levels of oxidative stress in their bodies than those without mental illness, a meta-analysis in JAMA Psychiatry has found. Oxidative stress occurs when there is an imbalance of free radicals and antioxidants in the body. A certain amount of oxidative stress is normal and occurs when the body fights off illness or repairs injury. However, long-term oxidative stress can damage cells, DNA, and RNA, leading to chronic inflammation in the body that raises the risk of numerous conditions like Alzheimer’s disease, cardiovascular disease, diabetes, and Parkinson’s disease.
The study’s findings may help explain why people with mental illness tend to have a higher rate of physical illness, Anders Jorgensen, M.D., Ph.D., of the University of Copenhagen and colleagues wrote.
The researchers analyzed data from 82 studies that compared markers of DNA and RNA damage from oxidative stress in people with mental illness with those in people without mental illness. The studies in the analysis used samples from different cell types, such as cells in urine, cerebrospinal fluid, and plasma, to discover markers of DNA and RNA damage in the body and brain caused by oxidative stress. All told, there were 10,151 patients with mental illness and 10,532 people without mental illness in the meta-analysis.
The researchers found a general trend of higher oxidative stress levels in patients with dementias, followed by psychotic disorders and bipolar disorders compared with people without these conditions. Patients who had major depressive disorder tended to have greater blood cell and plasma or serum DNA markers of oxidative stress, but not urinary DNA or RNA markers, than those without major depressive disorder. The meta-analysis included few studies of people with substance use disorder or anxiety disorders, so the researchers considered their findings inconclusive. However, the studies did not show a specific trend toward increased markers of oxidative stress in the brains of people with mental illness compared with those without mental illness.
“Given that there was an association with [oxidative stress] across many different diagnoses and matrices, and given that [oxidative stress] was not specifically increased in the brain, we consider it more likely to be [a byproduct] of the psychiatric conditions rather than a pathophysiologic factor underlying specific psychopathology,” the researchers wrote. “This finding is consistent with growing evidence showing general, transdiagnostic signs of accelerated aging and age-related illness in psychiatric disorders.”