Serotonin, Social Interaction and Making Decisions

The role of specific neurotransmitters and neurotransmitter circuits in decision making is being explored in a variety of ways.  Dopamine appears to have significant research support for a key role in making decisions related to reward.


The role of serotonin in decision making is less well studied but also appears to be important.  Robert Rogers, Ph.D. recently presented some of his lab's research at the Warren Frontiers in Neuroscience lecture in Tulsa, Oklahoma.  (Additionally, I have reviewed and placed a link to a recent research manuscript from Dr. Rogers related to topic below.)


Dr. Rogers noted the relationship between serotonin, depression and social function include these research findings:

• Social isolation is a known risk factor for major depression
• Serotonin appears important in developing nourishing social contacts
• Social isolation found in anxiety and depression may be mediated by serotonin mechanisms

Serotonin mechanisms in human research is aided by the safe ability to modulate brain serotonin levels.  Brain serotonin can be temporarily depleted using a amino acid drink deficient in the serotonin precursor L-tryptophan.  Humans without mood or anxiety disorders show an increase in brain serotonin after a week of administration of any of commonly used selective serotonin reuptake inhibitors.

Depleting serotonin or augmenting serotonin can be combined with a variety of behavioral and brain imaging techniques.  Dr. Rogers note his lab has recently documented several findings in adult control subjects without current or past anxiety or depression:

• Tryptophan depletion decreased measures of cooperative interaction in a resource management game known as the Prisoner's dilemma
• Tryptophan depletion appears to impair the ability of individuals to learn from a social cooperation task
• When working on a resource decision task, trytophan depletion changed decision-making behavior in women but not in men
• The antidepressant citalopram reversed the decision making behavior changes found in women with tryptophan depletion
• The brain medial prefrontal cortex is activated when individual observe the social decision-making behavior of others
• When working in groups on a resource harvesting task, tryptophan depletion produces a tendency to revert to the mean behavior in the group, even when this results in an earlier adverse group outcome

Dr. Rogers notes that these findings support more research in clinical populations suffering from a mood or anxiety disorders.  Serotonin dysregulation found in depression and other psychiatric disorders may go hand-in-hand with deficits in initiating social interaction, impaired learning from social interaction experience and making adverse decisions in social situations.

Photo of Coopers Hawk from the author's private collection.  

Rogers RD (2011). The roles of dopamine and serotonin in decision making: evidence from pharmacological experiments in humans. Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology, 36 (1), 114-32 PMID: 20881944