Who is the one most likely to commit suicide high serotonin level?

The one that most likely to commit suicide is: a 40-year-old with low serotonin activity

Serotonin is the one that control most of positive mood that happen to human (such as sexual desire, sense of appetite, sense of excitement, etc)

People with low serotonin activities tend to rarely or never experience such positive things in their life, which would increase their tendency to commit suicide.