Nerve fault linked to domestic abuse

In the UK 10% of women suffer domestic violence

Some men who carry out domestic violence could have an irregularity in their nervous system stopping them from controlling their emotions, research claims.

A study, involving participants in America, revealed differences in the autonomic nervous system of abusers.

But psychological experts warn the study is too small and needs more evidence before it can be regarded as firm proof.

Domestic violence is agreed as being a "complex phenomenon", dependent on a range of circumstances and interactions between victims and perpetrators.

Differences

Dr John Umhau, who lead the study, from the National Institute on Alcohol Abuse and Alcoholism, makes it clear that domestic violence happens as a result of a mix of elements.

Incidents of domestic violence occur world-wide - in the US 30% of all women who are murdered are killed by their husbands, boyfriends or ex-partners.

In the UK at any one time, 10% of women are suffering domestic violence, and up to a quarter of women will suffer domestic violence at some point during their lives.

The researchers found that when studying the autonomic nervous system, they detected precise differences in the regulation of the heart rate of abusers.

They speculate this could be found in other parts of the body involved in expressing rage such as voice and throat.

We have to be very careful in the area of domestic abuse. Domestic abusers can look for a cop out and reason for saying 'this is not my responsibility'

Ian Hancock, BPS

When domestic abusers become violent they often show extreme responses such as heart palpitations, breathlessness, trembling voice and body as well as flushing and sweating.

These all stem from the autonomic nervous system - which is generally not consciously controlled.

A group of 44 people underwent a simple test to measure the performance of their autonomic nervous system.

Test

Of these, 16 were domestic violence perpetrators. They were compared with 13 non-violent alcoholics and 15 healthy volunteers.

They were each asked to go from resting in a bed to standing quietly by their bedside for five minutes.

Such an action is a known natural stress inducement which raises heart rate.

Dr Umhau and his colleagues looked in particular at two measures of the autonomic nervous system - heart rate and something called the vagal nerve activity which is one of many heart rate regulators.

Usually as heart rate increases the vagal nerve activity decreases.

The vagus acts rapidly to changes such as agitation or even a simple change of posture, to adjust the heart rate, says Dr Umhau.

After the exercise Dr Umhau and his colleagues found that all the group displayed the correct decrease in vagal nerve activity as the heart rate increased.

But under more specific analysis, it was only the healthy volunteers whose results showed that minute-by-minute changes in vagal nerve activity predicted changes in heart rate.

The group of abusers had no such predicted change of heart rate.

Future studies could confirm this alteration in the heart rate regulation, said Dr Umhau.

Caution

He said of the study: "(This) in turn, may be found to affect the perpetrators' ability to modulate emotion and to control aggression," he added.

Ian Hancock, director of psychological services and research and a member of the British Psychological Society, advised caution.

(This) in turn, may be found to affect the perpetrators' ability to modulate emotion and to control aggression

Dr Umhau

He said: "There could be a danger of making assumptions here.

"Violent abusers could find this fault in their nerves is actually the result of them responding to perceived provocation over a period of time."

Mr Hancock, who works for Dumfries and Galloway Primary Health Care Trust, said: "We have to be very careful in the area of domestic abuse. Domestic abusers can look for a cop out and reason for saying 'this is not my responsibility'."

He said he welcomed the author's use of the word "speculate" and said further, larger studies are needed.

"And if they have got a point it should also be considered whether this fault is solely related to domestic abusers - or could the same be true for say football hooligans say."

Dr Umhau hoped his study's findings could help in understanding what turns a person to domestic violence.

The report is published on Friday in Psychophysiology, the official journal of the Society for Psychophysiological Research.