The activity of a brain enzyme thought to affect mood may be reduced in teens who commit suicide, according to US researchers.
Protein kinase C activity was lower in teens who committed suicide
Dr Ghanshyam Pandey and colleagues at the University of Illinois at Chicago examined the brains of 34 teenagers who had died - 17 by suicide.
Protein kinase C (PKC) activity levels were much lower in the suicide victims' brains.
The findings are reported in Archives of General Psychiatry.
PKC may be a target for therapeutic intervention in patients with suicidal behaviours
Lead researcher Dr Ghanshyam Pandey
Protein kinase C, a compound involved in cell communication, has been linked with mood disorders such as depression in the past.
Dr Pandey and colleagues were interested to know whether any link existed between changes in PKC and teenage suicide.
Of the 17 teenagers who had committed suicide, nine had a history of mental disorders.
The other eight had no psychiatric history, but two of them had a history of alcohol or drug abuse.
PKC activity was significantly decreased in the brains of these teenagers compared with the brains of teenagers who died from other causes.
Dr Pandey's team believe abnormalities in PKC may explain why some teenagers are likely to commit suicide.
"PKC may be a target for therapeutic intervention in patients with suicidal behaviours," they said.
But they do not know how or why PKC abnormalities might have an effect.
Dr Peter Parker, principle scientist at Cancer Research UK's London Research Institute, said there were concerns over sampling post mortem material because proteins such as PKC degraded with time.
This might affect the results if there was a delay in sampling for any reason, he said.
A spokeswoman for Depression Alliance said it welcomed any advances in understanding why young people take their own lives.
"Incidences of depression in teens and young adults has been increasing in recent years, and worryingly, 20% of all deaths by young people are by suicide.
"Understanding more about the enzyme protein kinase C could be vital in ensuring that effective treatments can be targeted where appropriate as part of a holistic package of care."
She said Depression Alliance would like to see further research in the area of depression, suicide and young people.
Phillip Hodson, a fellow of the British Association for Counselling and Psychotherapy, said the main question remained unanswered - whether abnormalities in PKC increase suicide risk or whether increased suicide risk caused abnormalities in PKC.