Some children of parents with a history of psychiatric illness may be at higher risk for attempting suicide and/or engaging in violent behaviour, a new Danish study suggests.
Danes born to parents who had themselves attempted suicide, or who had struggled with antisocial personality disorder or marijuana abuse, were found to face the biggest risk for attempted suicide or violence – up to four times as high, the study contended.
But, study lead author Pearl Mok stressed that, despite any potential elevated risk, people born to parents with a psychiatric illness or a violent history aren't necessarily fated to experience similar difficulties.
In fact, most such children won't experience any related problems.
"Of the over 1.7 million people included in our study population, 2.6 percent first attempted suicide and 3.2 percent were convicted of a first violent offence during the study period," Mok said.
Read: Attempted suicide: risk life-long
"Therefore, the vast majority of individuals, irrespective of whether their parent or parents have had a history of psychiatric illnesses, did not engage in these two harmful behaviours," added Mok, a research associate at the University of Manchester in England.
Also, the study only showed an association, not a cause-and-effect link.
To explore the issue, investigators sifted through psychiatric and crime registries in Denmark.
The focus was all Danes born between 1967 and 1997. All of the children were living in Denmark when they turned 15 years old.
The researchers first compiled a history of parental psychiatric illnesses. These included mental and mood disorders, schizophrenia, anxiety, Alzheimer's-related dementia, personality disorders, substance abuse and attempted suicide.
Read: Suicidal teens make first try before high school
Parental histories were then compared with attempted suicides and/or violent behaviour among their children. The researchers looked for behaviour that resulted in an adult criminal conviction through December 2012. These convictions included murder, assault, robbery, violent threats, rioting, kidnapping and sexual offences.
Mok said the children of parents with a history of any psychiatric illness were about 2.3 times more likely to be convicted of a violent offence. They were also 2.5 times more likely to attempt suicide than those whose parents had no such diagnosis.
Nature plus nurture
The study was published in JAMA Psychiatry.
The researchers said they also uncovered a gender gap in regards to elevated violence risk. The risk was greater among female children of parents with psychiatric illness than male children. But, male children in general – regardless of parental mental health status – exhibited more violent behaviour overall, the researchers said.
"Thus, women exposed to parental mental illness deviated far more than their unexposed female peers in their incidence of violent offending than was the case with exposed men compared to their unexposed male counterparts," said Mok.
But, exactly why remains unclear.
Mok said the rise in risk among the children is "most likely [due] to a combination of nature plus nurture".
However, such children "may also be at heightened risk of being additionally exposed to other adversities such as maladaptive parenting practice, abuse, neglect and financial hardship," she noted.
Read: Child abuse sufferers abuse alcohol as adults
"Shared genetic vulnerability" may play a role, Mok added.
Dr David Brent is an endowed chair in suicide studies and a professor of psychiatry at the University of Pittsburgh. He was the lead author of an editorial that accompanied the study.
He echoed Mok's point that such children aren't doomed to struggle.
The new study, he said, offers a "clue about which youth to be vigilant about in terms of development of suicidal behaviour or violence."
"[But] genetics or environment is not destiny," Brent added.
"The risk is increased, but the majority of youth even in the high-risk group will be unaffected," he said.
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