More on suicide - biological aspects

The social aspects of suicide were discussed in the previous post. There are many other factors. For example it is found that suicide is more common in some families. Both genetic factors and shared environment could be behind this. Studies have been done to clarify more on this. There is some evidence to say that genetic factors may be operating independent of the environment. Environment also has its share.
There are many studies showing that levels of a brain chemical called serotonin (a neurotransmitter acting as messenger between nerve cells) is low in the brains of suicide victims. Further it is also shown that still lower levels are seen if the suicide is by a violent method (jumping before train for example).
It is also known that people with low serotonin tend to be highly impulsive in their behaviors. They are also prone to develop depression. It can surmised from the above that serotonin plays a key role in regulating our mood, ability to control our emotions and behaviors etc.
It may not be possible to explain everything about suicide (or complex human behavior in general) with a single theory. This is why psychiatrists advocate the bio-psycho-social model of illnesses.