Men with a drug or alcohol addiction are up to seven times more likely to beat their other half, research suggests.
Alcohol is known to trigger aggression, which is thought to be down to its effect on the brain, according to Drinkaware. Less was known, however, about the “direction and magnitude” of the violence.
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To learn more, scientists from the University of Oxford tracked 140,000 men who had been diagnosed with a drink or drug problem at some point over 16 years.
Among those with a drug problem, 2.1% had been arrested for threatening, attacking or sexually assaulting their wife, girlfriend or ex - seven times higher than average - the BBC reported.
The alcoholics were 1.7% more likely to get in trouble with the law for such offences, six times higher than normal.
England alone is thought to have 586,780 dependent drinkers, of which less than a fifth (18%) are receiving treatment, Alcohol Change statistics show.
When it comes to drugs, around one in 11 (9.4%) adults aged 16-to-59 in England and Wales took an illicit substance last year, according to the Home Office.
To better understand how addiction affects behaviour, the scientists analysed multiple registers in Sweden to link male residents’ patient and crime data.
“Alcohol and drug use disorders decrease an individual's inhibition, which in turn can lead to the use of violence to solve conflicts in intimate relationships,” the scientists wrote in the journal PLOS Medicine.
Drinking can also affect our ability to think straight, according to Drinkaware. When faced with confrontation, many then “rise to the bait”, rather than shrugging the situation off.
In addition, alcohol brings about chemical changes in the brain that make people overly relaxed, stunting the “warning system” that usually arises in difficult situations.
In a drunken state, some also misinterpret the behaviour and cues of others, leading to fights over nothing more than a perceived “dirty look”.
The scientists also point the finger at mental health issues, with ADHD sufferers and depressives more at risk of arrest.
“People with mental disorders are also likely to use alcohol and drugs as coping strategies to deal with difficult symptoms associated with their illnesses,” they wrote.
“Therefore, alcohol and drug use disorders could be underlying mechanisms linking other mental disorders to later [domestic violence] perpetration.”
The team hope their results will improve drug and alcohol treatment, as well as how ex-offenders are monitored.
Others caution, however, the findings should be taken with a pinch of salt.
Dame Vera Baird, victims' commissioner for England and Wales, claims those who commit domestic violence while drunk may also be aggressive when sober.
Many perpetrators also do not have an addiction problem, she adds. It would therefore be a “mistake” to “divert resources” from domestic violence programmes into substance abuse.