The natural environment at home influences the anatomy of the brain

reference

Kühn S, Düzel S, Eibich P, et al. In search of characteristics that make up an “enriched environment” in humans: associations between geographical properties and brain structure. Scientific Rep . 2017; 7 (1): 1-8.

Study goal

to determine whether environmental factors in the place of residence have measurable associations with the morphology of the specified brain structures.

design and participant

Spatial Association study using brain scans with functional magnetic resonance imaging (FMRI) of 341 older adults (average age 70.1, SD = 3.89; 131 female), the in Berlin, Germany, life, and geocoded data of 4 land use types (urban green, water). and Ödland) within a radius of 1 km around the place of residence of the participants. The participants had no current or earlier diagnoses of cardiovascular or neuropsychiatric disease. The land usage data was taken from the Urban Atlas Date of the European Environment Agency. The results were checked in terms of age, gender, education and pension income.

target parameter

Functional magnetic resonance tomography scans of the following brain areas:

• amygdala: emotional regulatory center of the limbic system, combined with anger, fear, fear and an increased stress reaction
• perigenual anterior cingular cortex (PACC): also part of the limbic system, associated with emotion regulation, motivation and schizophrenia
• Dorsolateral prefrontal cortex (DLPFC): Part of the cognitive center of the brain, combined with working memory, planning, reason and inhibition

Structural equation model (SEM) was used to determine the relative amount, which each of the 4 land use types exercised on changes in the size and activity of the measured brain regions.

important knowledge

of the 4 types of land use tested only the proximity to a forest had a measurable effect on the 3 brain structures, and of these only the amygdala showed statistical significance (β = 0.232, se = 0.090; p = 0.010). This result was valid with a radius of 1 km and remained significant if it was tested again at a radius of 500 m and 2 km.

practice implications

In the meantime, it should be clear that exposure to natural environments of mental health can benefit, including mood, attention and memory ^{1 as well as morbidity and mortality rates. 2 This current study shows this key anatomically changes can occur through longer environmental loads. In particular, the connection between forests and changes in Amygdala activity indicates that life in forest areas not only promotes an acute feeling of relaxation during exposure, but also an increased long-term resistance to negative emotions such as fear and anger by redesigning the brain}

This is not surprising because the neuroplastic capacity of the brain has been recognized for many decades.

This study continues the pioneering work of leather arches and colleagues who showed that an adult's limbic system can be influenced by the green around the house of his childhood. ^{3 An essentially more rural childhood can benefit from how the brain of a person (especially amygdala and pacc) stress as an adult processed and perceived many years after they have moved. This resembles research that shows that activity such as meditation training can have positive effects on the emotional reactivity and the corresponding activity of the limbic system that remains years after the initial meditation training.}

This is not surprising, since the neuroplastic capacity of the brain has been recognized for many decades. ^{5 Since the late 1940s, studies have been carried out with rats that showed the effects of "environmental enrichment" on the brain structures as well as the corresponding behavior, the mood and memory. Enriched environments is standard practice in zoological environments with known effects on the brain structure and function of animals as well as morbidity and mortality. 8 It makes sense that people are also affected by the environmental context in which they live.}

For humans, this context is increasingly the urban environment. According to the 2010 US volume, over 80 % of the US population live in an urban area, whereby forecasts for a persistent urban growth are available. ^{9 This differs greatly from the environmental context in which people have developed and to which we are optimally adapted according to concepts such as the biophilia hypothesis of EO Wilson 10 or Ulrichs Psycho-evolutionary stress theory. 11 The urban environment produces many stressors, including traffic, noise pollution, air pollution and population density, which have all measurable adverse effects on the city. Known, a concept that was shaped in 1977 13 and since then well researched. Schizophrenia rates in urban environments up to 2.5 times higher, even after taking into account the reasons why people with this disease may prefer to move to cities (e.g. better access to psychiatric services).}

Although even more work is to be done to understand the complex interplay of environmental and individual factors, it is clear that our surroundings are more than just a passive part of our experience. They are an integral part of what determines the health of our mind and body.

restrictions

This was a cohort study by people who lived in the apartments of their choice, not an experimental design. Therefore, it is not possible to assign a causality of the land use type based on these results. However, this study design is widespread in public health research, since it would be unethical and very expensive to assign different places of residence indiscriminately and to demand from the participants to live there for several years.

Another restriction of the study is the 9-year gap between the land use data set (2006) and the brain scandates (2015). While the type of land use in Berlin does not change very quickly, it is possible that the country use data from 2015 would be different and thus influence the data results.

this study only looked at 1 km radii of the participants' residential addresses, not where they spent their time or what they looked at. It is possible that their environmental pollution was somewhat different from this study. For example, the study did not measure how much time the participants spent outside their houses or looked out of their windows or how much time was spent in these places. In view of the average age of the participants (70 years), however, it is likely that a significant part of the time was spent in this place.

conclusions

This study complements the research evidence that environmental factors influence structural changes in stress -related areas of the brain. Doctors can include this information in aspects of their clinical encounters, which either refer to the patient's medical history survey (e.g. "How green is it at their place of residence?") Or to recommendations for therapeutic benefits (e.g. prescriptions for increased exposure to green areas).