Whatever the mechanism, the decreased level of the enzyme, protein kinase C (PKC), is a "vitally important observation that will help not only in understanding the neurobiological profile of teen suicide but also in advancing ideas for therapeutic intervention," said study author Ghanshyam Pandey.

It is still unsure at this time whether the decrease in hormonal level was a cause or an effect of the mental state leading to suicide. The brains of 34 teenagers, half of whom had committed suicide and the rest, who died from other causes, were examined.

Thirty thousand Americans die of suicide annually and it is the second-leading cause of death among U.S. teenagers.