Marijuana permanently lowers IQ by several points in adolescents, according to research published in August. But a new study suggests that factors related to economic class and home life, not ...

A new analysis is challenging the idea that smoking marijuana during adolescence can lead to declines in intelligence. Instead, the new study says, pot smoking may be merely a symptom of something ...

IQ scores are on a decline, reversing a trend that saw scores rising at a steady rate during the 20th century, according to a new study. Researchers from the Ragnar Frisch Centre for Economic Research ...

Communities started adding fluoride to the water supply in 1945. But now, a new analysis finding a potential link between added fluoride and lower IQs in children is causing concern. The National ...