Natural disasters can be used by scientists to study prenatal stress

Natural disasters can be used by scientists to study prenatal stress

“In January 1998, just such a disaster occurred in Canada. It resulted in power outages that left millions of Quebec residents to brave the damage and severe cold without electricity and heat for up to six weeks. It also offered an unusual chance for scientists to examine the effects of maternal hardship on unborn children. Researchers at McGill University, Montreal (D. P. Laplante, 2004; D. P. Laplante, 2008) used this natural disaster to study the effect of stress on the children of women who were pregnant during or became pregnant within three months of the storm. They were able to separate the “objective” stressors (days without power) from the “subjective” reactions (intrusive thoughts or images) and physiological reactions (cortisol over 24 hours), and maternal personality factors of 178 pregnant women exposed to the disaster.

Children tested at ages 6 months, and 2, 4, 5.5 and 6.5 years showed significant negative effects on their temperament and and parent-and teacher-rated behaviors. Their motor development, physical development, IQ, attention, and language development were below average. The difference of an average of 15 IQ points between the high and low stress groups were largely maintained as of 2009, that is for eight and a half years (D.P. Laplante, 2008; A. Charil, 2010). The researchers concluded that the more severe the level of prenatal stress, the poorer the outcome.

Thirteen years later, the same research group investigated DNA methylation profiling in T cells (white blood killer cells) obtained from 36 of the children, and compared selected results with those from  These data provide first evidence in humans supporting the conclusion that prenatal maternal stress results in a lasting, broad, and functionally organized DNA methylation signature in several tissues in offspring. By using a natural disaster model, we can infer that the epigenetic effects found in Project Ice Storm are due to objective levels of hardship experienced by the pregnant woman rather than to her level of sustained distress (L. Cao-Lei, 2014). In other words, extreme stress causes long-term genetic changes in gene expression related to the immune system.

But there is more. Excessive and sustained stress also leads to a marked decrease of neurons in the amygdala and the prefrontal cortex. This will predispose an individual to poor academic performance, poor capacity to learn from past mistakes and a tendency to take abnormal risks (M R Dadds, 2006; Lyoyd DeMause,1982; Abigail Marsh, 2008). In addition, because stress decreases the production of oxytocin, the so-called love hormone and increases the production of vasopressin, a hormone that supports aggressive behaviour, this person will more likely behave in antisocial ways.

If a child demonstrates both, conduct problems  and callous–unemotional traits, their risk for psychopathy rises exponentially.  The oxytocin/vasopressin system is a likely candidate for contributing to the development of psychopathy (Mark R. Dadds, 2014).  Finally, acute or low grade chronic stress leads to increased dominance of lower brain centers over higher centers, particularly the prefrontal cortex, an area of the brain that has developed most recently in the evolution of primates and makes us most human – in the best sense of the word. Due to a confluence of all these factors, this child will have a very strong propensity to develop a Personality Disorder.

Common to all personality disorders are four core phenomena: distorted thinking patterns, problematic emotional responses, over- or under-regulated impulse control, and interpersonal difficulties. Before a diagnosis is made, a person must demonstrate significant and enduring difficulties in at least two of those four areas. Personality disorders are not usually diagnosed in children because of the requirement that they represent enduring problems across time (DSM-5). When children become angry, resentful, easily annoyed, and just in plain English difficult to manage, the most frequent diagnosis is Oppositional Defiant Disorder ODD). If they progress to physical violence or engage in criminal activities such as stealing, the diagnosis is Conduct Disorder. Early treatment often helps but obviously prevention is preferable to treatment.

The origin of autism spectrum disorder is still a mystery. The great majority of investigators agree that it must be the result of a combination of factors both genetic and and environmental. However, most scientists when they say “genetic” assume that genes represent unalterable destiny that you inherit from your parents at conception. Of course epigenetics teaches us that gene expression is modulated by environmental factors both external and internal to the mother. These may run the gamut from pollutants in the air, recreational drugs the mother inhaled or otherwise introduced into her system, nutrition or lack of it, maternal stress, depression and anxiety. Therefore, the role of the environment in shaping the brain and body of the unborn child cannot be overstated.

A more severe form of a mental disorder than autism is schizophrenia. A new study discovered pregnant women who endure the psychological stress of being in a war zone are more likely to give birth to a child who develops schizophrenia. Research supports a growing body of literature that attributes maternal exposure to severe stress during the early months of pregnancy to an increased susceptibility to schizophrenia in the offspring (Dolores Malaspina, 2008).”

Thomas Verny MD.
Excerpted from the manuscript of a new book by Thomas R Verny MD, permission granted

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