Researchers have shown that the parts of the brain dealing with stress and emotion are affected by living among the crowds.
The findings help shed light on why those who are born and raised in urban areas are more likely to suffer from anxiety, depression and schizophrenia than those brought up in the countryside.
Country life: Past findings have shown that exposure to green space boosts health and reduces stress
However, past studies have shown that exposure to green space reduces stress, boosts health and makes us less vulnerable to depression. The findings come from the brain scans of 32 healthy volunteers from urban and rural areas.
Dr Jens Pruessner of the Douglas Mental Health University Institute in Quebec, who helped carry out the study, said: ‘Previous findings have shown that the risk for anxiety disorders is 21 per cent higher for people from the city, who also have a 39 per cent increase for mood disorders.
‘In addition, the incidence of schizophrenia is almost doubled for individuals born and brought up in cities. These values are a cause for concern.’
Dr Pruessner and colleagues from the Univerity of Heidleberg in Germany monitored the brain activity of adult volunteers while they carried out mental arithmetic puzzles under time pressure.
The functional magnetic resonance imaging scans revealed that the brains of those living in cities reacted differently to stress, the researchers report in the journal Nature.
The region of the brain called the amygdala – involved in mood and emotion – was more active among the volunteers raised in cities, they found.
And those with an urban upbringing had a more active cingulate cortex – a region involved in regulating stress – while carrying out the task.
A larger study would be needed to confirm the findings. The researchers are unsure why city life affects the regions of the brain that handle stress.
Pollution, toxins, crowding or noise could all contribute, they say.
However, past studies have shown that access to green space soothes frayed nerves and improves well-being.
In 2009 Essex University scientists showed that as little as five minutes in a green space cut stress.
Other studies have shown that those with access to countryside are less likely to have heart disease or strokes.
Psychologists have argued that millions of years of evolution means the human brain has not developed to cope with life surrounded by thousands of strangers.