However, in the case of prescription drugs, the drug is always innocent and the person guilty, a psychiatrist has said.
David Healy, an Irish-born professor based in the UK, has been an expert witness in homicide and suicide trials involving psychotropic drugs. He believes selectove serotonin re-uptake inhibitor (SSRIs) anti-depressants can cause a delirium that leads to violent behaviour.
“They can also cause entirely normal people to start thinking aggressively and have violent thoughts they had never had before, as they did to some drug trial volunteers in Leeds in the 1980s.
“And they can switch off anxiety so that someone coldly starts to plan something they would be too scared to do ordinarily — so there can be pre-meditation. The problems can happen within 48 hours, or build up over two to three weeks, as in Shane Clancy’s case.”
Prof Healy gave expert evidence at the inquest of Mr Clancy, who killed a man before taking his own life.
This view is strongly disputed by the College of Psychiatry of Ireland, which maintains there is no evidence anti-depressants can cause harm.
The college believes discussion of suicide and homicide as potential adverse effects of antidepressant medications, particularly SSRI anti-depressants, is speculative.
“Clearly, suicide and homicide are events of the utmost gravity and any possible role of any treatment in precipitating such tragedies warrants the most thorough investigation,” according to the college.
“However, discussion of the risks involved must be based on evidence rather than conjecture or unfounded personal opinion.”
Former deputy state pathologist Declan Gilsenan warned in this newspaper yesterday that he had seen too many suicides of people who had recently started taking powerful anti-depressants.
He said he would be willing to sit down and share his concerns with Kathleen Lynch, the minister with responsibility for mental health.
On suicide, Dr Gilsenan said that while there were a lot of people trying to solve the problem, nobody — including psychiatrists — had and it was getting worse.
“I worked in the Midlands in the 1980s and saw about five cases of suicide a year. In 2010, I was seeing 25-30 in that one area alone with a population of about 200,000. That is a huge increase. I think people are not observed and monitored the way they used to be in the past and perhaps that is part of the problem.”
Ms Lynch congratulated Dr Gilsenan for speaking out in public as it was such a difficult issue to tackle.
She said the former coroner could have picked any issue but the fact that he picked this one was significant.
“When someone of this stature speaks out, we have to take notice,” she said. “GPs have found themselves in a position where there is nothing else to do but prescribe pills. There needs to be alternatives for people. It can’t just be medication, and we need a system where people are reviewed on a continuous basis.”
Ms Lynch said work was in progress to close gaps in psychology and counselling services in the community, and that people in emotional difficult needed to be treated with the upmost care.
Dr Gilsenan called for a national survey of suicides to see how many people had begun taking SSRIs shortly before taking their life.
He said toxicology reports were vital in this regard but were expensive tests which were sometimes not carried out.