new research suggests.
Results from a cohort study of more than 4.2 million individuals showed that offspring of mothers with PIDs had a 17% increased risk for a psychiatric disorder and a 20% increased risk for suicidal behavior, compared with their peers with mothers who did not have PIDs.
The risk was more pronounced in offspring of mothers with both PIDs and autoimmune diseases. These risks remained after strictly controlling for different covariates, such as the parents’ psychiatric history, offspring PIDs, and offspring autoimmune diseases.
The investigators, led by Josef Isung, MD, PhD, Centre for Psychiatry Research, department of clinical neuroscience, Karolinska Institutet, Stockholm, noted that they could not “pinpoint a precise causal mechanism” underlying these findings.
Still, “the results add to the existing literature suggesting that the intrauterine immune environment may have implications for fetal neurodevelopment and that a compromised maternal immune system during pregnancy may be a risk factor for psychiatric disorders and suicidal behavior in their offspring in the long term,” they wrote.
The findings were published online in JAMA Psychiatry.
‘Natural experiment’
Maternal immune activation (MIA) is “an overarching term for aberrant and disrupted immune activity in the mother during gestation [and] has long been of interest in relation to adverse health outcomes in the offspring,” Dr. Isung noted.
“In relation to negative psychiatric outcomes, there is an abundance of preclinical evidence that has shown a negative impact on offspring secondary to MIA. And in humans, there are several observational studies supporting this link,” he said in an interview.
Dr. Isung added that PIDs are “rare conditions” known to be associated with repeated infections and high rates of autoimmune diseases, causing substantial disability.
“PIDs represent an interesting ‘natural experiment’ for researchers to understand more about the association between immune system dysfunctions and mental health,” he said.
Dr. Isung’s group previously showed that individuals with PIDs have increased odds of psychiatric disorders and suicidal behavior. The link was more pronounced in women with PIDs – and was even more pronounced in those with both PIDs and autoimmune diseases.
In the current study, “we wanted to see whether offspring of individuals were differentially at risk of psychiatric disorders and suicidal behavior, depending on being offspring of mothers or fathers with PIDs,” Dr. Isung said.
“Our hypothesis was that mothers with PIDs would have an increased risk of having offspring with neuropsychiatric outcomes, and that this risk could be due to MIA,” he added.
The researchers turned to Swedish nationwide health and administrative registers. They analyzed data on all individuals with diagnoses of PIDs identified between 1973 and 2013. Offspring born prior to 2003 were included, and parent-offspring pairs in which both parents had a history of PIDs were excluded.
The final study sample consisted of 4,294,169 offspring (51.4% boys). Of these participants, 7,270 (0.17%) had a parent with PIDs.
The researchers identified lifetime records of 10 psychiatric disorders: obsessive-compulsive disorder, ADHD, autism spectrum disorders, schizophrenia and other psychotic disorders, bipolar disorders, major depressive disorder and other mood disorders, anxiety and stress-related disorders, eating disorders, substance use disorders, and Tourette syndrome and chronic tic disorders.
The investigators included parental birth year, psychopathology, suicide attempts, suicide deaths, and autoimmune diseases as covariates, as well as offsprings’ birth year and gender.