Higher risk of depression in the city

City dwellers have a higher risk of depression

06/25/2011

According to a recent study, the brain regions of city people are measurably changed. As a result, the stress regulation is impaired, so that people in the city are at a higher risk of suffering from mental illness such as depression or anxiety disorders. In addition, researchers of the Central Institute of Mental Health (ZI) in Mannheim could identify an increased risk of schizophrenia.

Higher risk of anxiety and depression in big cities
Life in the city, in addition to an increased risk of accidents and heart attacks, also carries the risk of developing mental illnesses such as depression or anxiety disorders. Relatively large, the risk of disease is much higher in the city than in rural areas. In addition, if children grow up in large cities, the risk of developing schizophrenia is two to three times higher than in rural areas. Responsible for this context is a dysfunction in the brain regions of city dwellers which are responsible for the control and regulation of emotions and stress. For the first time, concrete results could be obtained from the scientific team headed by Prof. Andreas Meyer-Lindenberg from the Central Institute for Mental Health (ZI) in Mannheim in the Forschermagazin „Nature“ to be published. The research was done in collaboration with McGill University in Montreal.

Brain areas were examined by MRI
A total of 160 volunteers from cities and rural areas participated in the study. All participants were examined by magnetic resonance imaging (MRI). The focus was on the brain areas of the amygdala. Brain activities were measured under stress and control conditions. For this, the volunteers had to deal with difficult arithmetic tasks. In addition, they were almost verbally abused and subjected to sharp criticism. Thus artificially a stress situation could be brought about.

It was striking that in the urban subjects, the amygdala was significantly more active than in the rural study participants. The named brain region is a so-called core region in the human brain that belongs to the limbic system. In experiments, researchers have already been able to prove that electrical impulses at different points of the amygdala can cause different reactions. Signals in the center led to tantrums or escape reactions. At other points vegetative situations could be provoked. For example, tachycardia (high heart rate, rapid heart rate), craving for eating or procreative instinct could be triggered.

For city dwellers, significantly stronger activities were measurable during the MRI, according to psychiatrist and physician Prof. Meyer-Lindenberg. The subjects, who grew up in cities like Hamburg or Berlin, also reacted much more so-called cingulate cortex (a part of the frontal lobe of the brain), as in rural adults. "These two regions in the brain are particularly susceptible to stress," explains Meyer-Lindenberg.

The larger the place of residence, the greater the activity of the anxiety center
During the stress situation, the typical parameters were measurable. Accordingly, the pulse, blood pressure, and cortisol levels rose. This reaction was the same for all participants. Of value, however, was the activity of the anxiety center. The larger the place of residence of the participant was, the more active the amygdala was. When the test subject grew up in a city, increased frequencies of the perigenual anterior cingulate cortex (pACC) were also revealed. Here it could be observed that in the adult participants, the connection between amygdala and pACC functioned much weaker than in others. This observation is so far unique and could be helpful for neurological research. Because a disturbed brain circuit has been discussed for some years as a risk factor for mental illness in the researcher world. For example, there could be an increased risk if certain neurological functions are altered.

In exact numbers, the scientists were able to visualize the consequences. According to current studies, city dwellers are at an increased risk of depression of 39 percent. The bigger the city, the higher the risk of developing a manifested depression. The risk of developing an anxiety disorder was higher at 21 percent. Anxiety disorders is one „unspecific anxiety without specific reason“. In the acute case, patients suffer a panic attack. This is accompanied by tachycardia, tremors, shortness of breath, excessive sweating, inner restlessness, dizziness and derealisation.

Exact causes need to be explored
Subsequent studies will now investigate exactly why urbanites are so stressed out. Most scientists assume that the increased noise level and spatial confinement in which people live together are responsible. "If we know the exact reason, this can be taken into account in urban planning," emphasized the head of the center. For depression, stress-related diseases such as burn-out and anxiety disorders have been rising for several years. In contrast, more and more people live in cities. According to the latest analyzes about half of the world's inhabitants live in cities or large cities.

The Central Institute for Mental Health is a psychiatric clinic and research institution in Mannheim. The "ZI" links patient care and research and teaching in the field of mental disorders. A total of four clinic complexes belong to the foundation. (Sb)

Also read:
City life increases stress susceptibility
Psychosis risk: city people fall ill more often

Image: Barbara Eckholdt, Pixelio.de