Acute Stress During Birth Linked to Schizophrenia in Children
We’ve known for some time now that stress is not conducive to healthy living. It affects us in a myriad of ways from something simple like not being able to concentrate, all the way through to raised blood pressure. But in a Time article recently, it was shown that stress can also increase the risk of a child developing schizophrenia later in life if during the pregnancy, the mum suffers from acute stress.
I’m using ‘acute’ before the word ‘stress’ because it is necessary to be clear on just what stress we’re talking about. This is not the stress of facing a mid-term exam or wondering if the kitchen is clean while on holiday. This sort of acute stress is that caused by a death in the family, or something similarly serious.
But even before we can look at the links to schizophrenia, we have to look at what we already know about stress and pregnancy.
A study published in the UK medical journal The Lancet in 2000 suggested that a mother’s stress during pregnancy may increase the risk of the child developing congenital (existing at and usually before birth) brain malformations. It has also been well established that maternal stress is directly associated with low birth weight and premature births.
So the idea that a mother’s stress during pregnancy affects her child is not new.
But in an article published in a recent edition of the Archives of General Psychiatry journal, a new study conducted in Denmark looked at 1.38 million Danish births from 1973 to 1995 born to mothers who were considered exposed to acute stress during the pregnancy.
The term “considered exposed” was defined by whether any of ‘their close relatives died or was diagnosed with cancer, acute myocardial infarction, or stroke syndrome up to 6 months before conception or during pregnancy.’
As for the children, they were followed from their 10th birthday until ‘their death, migration, onset of schizophrenia (admissions were identified by linkage to the Central Psychiatric Register), or June 30, 2005.’
The results showed that the risk of schizophrenia and similar disorders was significantly raised in children whose mothers were exposed to the death of a relative during their first trimester. The risk percentage was 67%, but those who suffered from such stress prior to pregnancy or in the last 2 trimesters did not register in the findings.
The conclusions of the report stated that ‘our population-based study suggests that severe stress to a mother during the first trimester may alter the risk of schizophrenia in offspring. This finding is consistent with ecological evidence from whole populations exposed to severe stressors and suggests that environment may influence neurodevelopment at the feto-placental-maternal interface.’
With a sense of hindsight available to you, the study makes sense. The stress caused by the loss of a loved one – when compared to that of a disease or stroke – is significantly greater.
“The problem with diagnoses of heart disease and that kind of thing is that it’s likely that there has been worry about the health of that individual for some time,” says the study’s author, Kathryn Abel of the Centre for Women’s Health Research at the University of Manchester. “Once somebody gets admitted with a heart attack or stroke or a serious illness, in some way there is relief because they’re being managed — it might not be such an acute event, which we know death to be, even when someone has been ill for a long time. When they die, that’s it.”
Furthermore, Abel hypothesizes that the death of a child during pregnancy compared to the loss of a parent creates a higher risk of schizophrenia in a child’s life. However, thankfully, Abel’s sample size – ie, the amount of people to whom this happened – were too small to be certain of this theory.
I hinted at this study relating to “similar disorders” and Abel and her collaborators at the University of Aarhus in Denmark similarly suggest that such maternal stress does not limit its repercussions to schizophrenia. Other conditions, along the same theme, such as depression and other mental disorders, are believed to stem from maternal stress. “We have not shown that this is specific to schizophrenia. We’ve just only looked at schizophrenia,” said Abel.
Just how a mother’s levels of emotional stress affect the development of her unborn child is as yet still unknown; though there are many theories.
Some believe it has something to do with the stress hormone cortisol, which has been linked to the body’s responses to stress. It increases blood pressure, blood sugar levels, and reduces the effectiveness of the immune system. That this could be linked directly to fetal development is not a stretch of the imagination.
Still it may be that the mother’s stress is just a catalyst for a bounty of other responses, ranging from blood levels of sex hormones, her immune system as pointed out above, or in her cell-signaling proteins called cytokines.
But though the direct causal link between stress and a babies fetal-development are unknown, the repercussions lend credence to the theory that early in the pregnancy “mothers transmit information to their fetus about what condition they’re likely to be born into — whether they’re going to be thrifty and expect to be in a relative state of starvation, for example, or whether they can expect plenty — a clear evolutionary advantage,” says Abel.
“But it may be that in some settings, it has an adverse consequence because it restricts the growth of the fetus, and perhaps causes abnormal development of the brain, which makes it more susceptible to diseases, such as schizophrenia.”
Abel is not done though, and plans to soon replicate her findings in Sweden. Using a bigger study population with richer data, she will include the socio-economic status of models, which she believe will only enhance her study. “Social class is one of the big, enduring predictors of risk of mental illness. The lower the social class the higher the risk. You’re born with this risk,” says Abel.
All of this being said there is still one genetic trick to be played. While maternal stress is indeed a factor, the greatest factor in a person developing schizophrenia is genetics. First-degree family history is the most powerful risk of inheriting schizophrenia there is. But, and this is the “trick” I mentioned, if a mother deals with the above detailed maternal stress and has a genetic history of schizophrenia, the associated risk of schizophrenia from maternal risk disappears.
Whoever said this was easy?
A Geek’s-Geek from Melbourne, Australia, Josh is an aspiring author with dreams of publishing his epic fantasy, currently in the works, sometime in the next 5 years. A techie, nerd, sci-fi nut and bookworm.
Items of notes and interest from the web.