Just read an interesting article about how a certain serotonin transporter allele, known to cause depression in western cultures, for whatever reason, seems to be more abundant in collectivistic asian societies. Not only is it more abundant, but seemingly among those with the allele, they experience less depression. The article suggested that this comes from the less individualistic mindset within these cultures that allow for more social help during stressful times which ordinarily might trigger depression.
“A new analysis based on animal studies suggests that showering in manganese-contaminated water for a decade or more could have permanent effects on the nervous system. The damage may occur even at levels of manganese considered safe by the Environmental Protection Agency, according to researchers from Wake Forest University School of Medicine. [...] Everyone is exposed to small levels of manganese, which is found in food and many types of rocks and enters the air, soil and water. But, at higher levels, manganese is toxic to the central nervous system and can cause learning and coordination disabilities, behavioral changes and a condition that is similar to Parkinsonâ€™s disease.”
Though many scientists have hypothesized a link between serotonin and impulsivity, this is one of the first studies to show a causal link between the two. [...] The research also provides insight into clinical disorders characterized by low serotonin levels, such as depression and obsessive-compulsive disorder, and may help explain some of the social difficulties associated with these disorders. [...] UCLA scientists reported in April that the human brain responds to being treated fairly the same way it responds to winning money and eating chocolate; being treated fairly turns on the brain’s reward circuitry. In the new Science study, they and their Cambridge colleagues report that people with low serotonin levels were found to be more sensitive to being treated unfairly.