Study reopens debate on 'suicide gene'

 

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Genetic variation 'may increase risk of suicide'

A new scientific study has reopened the debate about whether suicide can be linked to physical conditions as much as external factors, the UK Press Association has reported.

Observable differences in genes relating to the growth of nerve cells may be a factor in the development of suicidal tendencies in individuals with depression, a new study published in American journal the Archives of General Psychiatry has concluded.

The research was led by Dr Martin Kohli and conducted at the Max Planck Institute of Psychiatry in Munich, Germany, and the John P. Hussman Institute for Human Genomics in Miami, USA.

Reporting their results, the study's researchers stated they had found that "the genetic risk factors for suicide appear to be independent from the underlying psychiatric disorder", indicating that genetic variations could be a significant factor in some self-inflicted deaths.

 

A study of suicide

The study analysed the genetic make-up of 394 patients who had been diagnosed with depression, 113 of which had attempted suicide on at least one occasion, and compared it with that of 366 individuals with no prior history of mental illness.

A follow-up study to confirm the original findings was later conducted using data from 1,600 German and African-American patients, 270 of whom had reported previously attempting to take their own life.

The scientists discovered five specific discrepancies in the genetic make-up of the analysed individuals, three of which were found to be more common among individuals with a history of suicide attempts.

According to the researchers, subjects displaying all three of these identified variations were 4.5 times more likely to attempt suicide in their lifetime than those who did not have any of them.

 

Suicide: Internal versus external, or internal and external?

The study is not the first to link incidences of suicide to internal physical conditions. In October 2008, a Canadian study had found people who die by suicide can have brains which are chemically different to those who have no history of self-harm.

John Krystal, editor of Biological Psychiatry which published the study, told the BBC: "These modifications may shape the course of one's life […] including increasing the risk for major depressive disorder and perhaps suicide."

The scientists found many of the people studied who had died by suicide had a higher rate of a process called methylation, which ordinarily regulates cell development. However, when the methylation rate was high, they discovered it shut down chemical message receptor genes, which play a major role in determining behaviour.

While the findings appear to again point to the fact that suicidal tendencies may be a result of internal differences, it is important to note that the study's authors point to environmental factors as being a possible cause of high-rate methylation.

Mr Krystal told the broadcaster: "This is exciting […] evidence that genetic and environmental factors may interact to produce specific and long-lasting modifications in brain circuits."

 

Does the 'suicide gene' exist?

While it appears that differences in people's genetic make-up can be at least a contributory factor in some suicides, scientists have yet to establish conclusively the existence of a specific 'suicide gene'.

Much research has been done into whether suicidal tendencies can be passed on through families. Indeed, the Archives of General Society report states: "Twin and family studies suggest that suicide and suicide attempts are heritable traits".

However, as yet no conclusion has yet been drawn as to the extent to which such occurrences are a result of an inherited genetic predisposition or the trauma left by the loss of a loved one through suicide.

Anecdotally, at least, it would appear that the suicide can be shown to run in families. David Porteous, Professor of Human Molecular Genetics at Edinburgh University tells the Guardian: "If you look at families where someone has committed suicide, the chances are that you will find another case in the not-too distant family."

 

The Plaths: A legacy of suicide?

Dr Porteous' assertion is tragically highlighted by the case of Nicholas Plath, who died by suicide aged 47 in March 2009.

Nicholas was the son of the poets Ted Hughes and Sylvia Plath. Sylvia also died by suicide when the couple's two children were still infants. While the reasons for Nichols' suicide are unknown he, like his mother, reportedly experienced severe depression.

However, Peter McGuffin, Professor of Psychiatric Genetics at the Institute of Psychiatry in London, warns that while the suicide of a family member may make an individual more susceptible to depression and suicide, it would be a mistake to assume that this is necessarily the case.

He tells the Guardian: "There is a lot of controversy about the impact of very early trauma on later depression".

 

Samaritans

If you are experiencing suicidal thoughts or emotional distress, you can call Samaritans for support 24 hours on 08457 90 90 90 (UK) and 1850 60 90 90 (ROI), or email at jo@samaritans.org, or face to face - visit http://www.samaritans.org/ for your nearest branch.

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