Urbanicity and Risk of Schizophrenia—New Studies and Old Hypotheses

Every man, wherever he goes, is encompassed by a cloud of comforting convictions, which move with him like flies on a summer day.

Bertrand Russell, Skeptical Essays, 1938^1(p28)

Studies from Nordic and northern European countries have reported an increased risk of schizophrenia in those who are born or raised in urban settings.² Clearly, urbanicity (usually defined as population density per square kilometer) is a proxy indicator for exposures that have not yet been identified and that are more or less prevalent in urban vs rural settings. Schizophrenia research cannot afford to ignore important clues like this, but the precise nature of the factors responsible for this association remains elusive.