Friday, October 20, 2006

Early verbal abuse may reduce language ability

Children who are verbally abused may suffer lasting negative effects in their brain’s ability to process language, researchers report.

They say the new findings illustrate the seriousness of this type of abuse and should encourage greater action to combat it.

Brain scans of people who were verbally abused as children showed that they have 10% less grey matter in the part of their brains involved in language, compared with non-abused adults.

Martin Teicher at Harvard Medical School in Boston, Massachusetts, US, and colleagues used an exhaustive questionnaire to select 17 people who had suffered severe verbal abuse in childhood but not other forms of abuse.

Experts define verbal abuse as frequent disparaging or critical comments that are intended to demean and diminish the victim’s self-esteem, he explains. The team recruited 17 additional participants for the trial, matched for age and socioeconomic status, who had suffered no such abuse.

Tone of voice

Brain scans revealed that those who had experienced verbal abuse had a 10% reduction in the size of a brain region known as the right superior temporal gyrus, compared with those who had not been abused. This part of the brain contains a section responsible for auditory processing and is believed to help the brain understand the tone of speech.

The scans also showed a significant reduction in a small part of the left superior temporal gyrus, which is thought to be involved in understanding the syntax of speech.

Teicher speculates that verbal abuse might inhibit development in the superior temporal gyrus, perhaps by triggering a pathway that stops growth hormones from reaching it.

Causal link?

The new experiment does not necessarily establish a causal link: the abnormalities could be a genetically inherited trait. But Teicher suspects the relationship is causal. For example, previous research has shown that victims of sexual abuse by non-relatives have decreased development in the visual processing parts of the brain, compared with people who have not suffered such abuse.

The brain abnormalities seen in the verbal abuse victims appear to be related to reduced language skills, Teicher adds. The subjects in the study who had experienced verbal abuse scored about 112 on a test of verbal IQ, on average, while their control counterparts had a score of about 124.

“I think they didn’t reach their full potential,” he says of the students who suffered verbal abuse and scored lower on the test.

Incredible anger

The results are important because they contribute to a growing body of evidence that the stress caused by early abuse – including neglect – can disrupt the normal development of brain "circuits", says Barbara Rawn of Prevent Child Abuse America, in Chicago, Illinois, US.

Teicher believes that parents have begun to grasp the negative effects of physically reprimanding their children, but he fears that parents may feel that no harm is done by frequently reprimanding their children with disparaging comments.

“Verbal abuse really has a long-term effect on a child,” says Rawn. “There’s a lot of incredible anger that shows up in kids that have been told they are worth nothing.” She adds that some children who have been verbally abused sometimes develop behavioural traits such as extreme aggression, or instead become overly compliant.

Teicher presented the new findings this week at the annual Society for Neuroscience meeting in Atlanta, Georgia, US.

Source: New Scientist

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