The Iniquity of the Fathers: Passing On the Effects of Abuse
Posted: under Health, Medicine, and Healthcare.
To my mind, the Bible is a poetic document, teaching its lessons in metaphors and parables. I’ve interpreted the instruction of God to the children of Israel regarding his first commandment and the sinfulness of the fathers as a caution on the long lasting effects of doing wrong: Sinfulness can get transferred from parent to child by bad example and by psychological mechanisms, such as identification with the aggressor.
But recent work in neuroscience and epigenetics suggests that a son’s experience of abuse by his father may be incorporated in methyl groups near a gene controlling the levels of corticosteroid stress hormones.
Epigenetics, a vigorous area of biological research, has yielded groundbreaking insights into mechanisms for incorporating changes experienced by an individual organism into its chromosomes and potentially passing those changes to succeeding generations. The most prevalent process is attachment of a methyl group (a carbon atom with a single binding site) to DNA in the chromosomes of a cell, usually at a cytosine unit of the genetic sequence. The change doesn’t affect the sequence itself, but can be passed onto daughter cells via the activity of the methylase enzyme, which replicates methylation patterns following replication of DNA. When methylation affects the DNA of germline cells, methylation patterns may be passed to offspring.
As for inheriting the effects of child abuse, an article in Science this month reports that researchers in Montreal examined the postmortem brains of men who had been abused by their fathers as children and committed suicide as adults. The neuroscientists compared them with brains from other men, who had not been abused but had died suddenly from suicide or other causes. They found increased methylation in the cells of the hippocampuses of the abused men.
The hippocampus is a region of the brain involved in processing emotions and memories, and the methyl groups were found attached at the promoter site of the gene for the glucocorticoid receptor. The gene is involved in controlling stress, since the receptor receives the stress hormone cortisol and initiates negative feedback to damp down secretion of the hormone. But when methyl groups get attached to the promoter, the gene becomes less active in controlling stress. It has been shown in rat studies that this methylation condition results in long-lasting high levels of stress experienced by the animals.
The research suggests that the abused men may have experienced high levels of stress hormones throughout their lives, because the experience caused the methylation of genes in their brains. Thus, methylation may be a mechanism whereby childhood experiences could exert life-long effects.
Although the researchers did not look at whether methylation also affected the genes of their germline cells, the fact that methylation may persist through replication would seem to allow for the possibility that the effects of abuse could last for generations.
So, perhaps the wisdom of the Biblical passage is supported in some unforeseen way not only by psychological mechanisms but also by biological ones.
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Feb 28 2009