Serotonin manipulations and social behavior: Studies in individuals at familial risk for depression

Interactions with others affect our mood, and vice versa. Unsurprisingly, people with a mood disorder such as depression often have difficulties in their social relationships. Depression is often thought to be associated with a decreased availability of serotonin, a signaling molecule in the brain which enables the processing of social and emotional information. Therefore a decreased availability of serotonin could also have an adverse effect on social behavior and mood during interactions with others. However, Hogenelst and colleagues showed that a temporary decrease of serotonin (over several hours) has little impact on mood or social behavior as measured in the lab. The results were similar in study participants with and without an elevated depression risk. In a second study in people with an elevated depression risk, the researchers increased the availability of serotonin over several days. They examined the effects on mood and social behavior in everyday life. As expected, mood improved. Unexpectedly, however, the participants also became less friendly. This behavioral effect was only seen during interactions at home. It is possible that, when serotonin availability was increased, participants stood up for themselves more. This in line with the idea that people prone to depression experience little control over their social lives. As most medications for depression aim to increase the availability of serotonin, an important next question is how these medications affect the social behavior of depressed people.