Anecdotally, the link between cities, stress and mental health makes sense. Psychiatrists know that stress can trigger mental disorders — and modern city life is widely perceived as stressful. City dwellers typically face more noise, more crime, more slums and more people jostling on the streets than do those outside urban areas. Those who have jobs complain of growing demands on them in the workplace, where they are expected to do much more in less time.
But the idea has not been widely tested. It is difficult to study whether something as complex as a 'city environment' has an impact on the brain. To complicate matters, many growing cities include immigrant populations, which already have an increased risk of psychiatric disease associated with social isolation.