By Andréa de Paiva
Did you know that the environment can affect your organism not only in an anatomical or functional level, but also at a molecular level? Can the spaces we occupy interfere on how our genes work? The area that studies such impacts is called epigenetics and it has been developing a lot over the last few years. In today's article we will discuss the intersections of two fields that have a lot to dialogue: epigenetics and NeuroArchitecture.
The DNA, that famous helix structure, contains genetic information that coordinate development and functioning of all living beings. It is through the DNA that hereditary qualities are transmitted to the next generations. It is formed by a combination of genes, known as genotype (or genome), which represents the set of development potentialities. This combination of genes is unique for each individual. The only exception to this rule are identical twins, who developed from the same zygote. The monozygotic twins share the same genetic instructions. But even so they still develop and behave differently throughout life. Why does it happen?
Questions such as this are related to the field that motivated the embryologist Conrad Waddington, considered the "father" of epigenetics. The influence the environment can have on embryo development results in diferences in individuals even when their genotype is identical. Such variations happen because the interaction between genotype and environment is unique for each living being and, consequently, epigenetic reactions are too. Even in the mother's womb, each twin has a particular interaction with that habitat, which results, among other things, in differences in the fingerprints from individuals that share the same genetic combination .
Nowadays, epigenetics is not restricted only to embryonal development. The environment (both physical and social) in which we are inserted - as well as personal habits - interacts with our genotype and influences epigenetic changes. Such modifications are very usual to our organism, however some specific alterations might result in the development of disorders.
But what do we know about the relation os architecture and urbanism with epigenetics? Are the spaces we design impacting on the gene expression of their users? Since this is a very complex field to be studied, we do not have all the answers yet, but researches conducted since the last century help to point to an interesting direction.
There are many studies that show that a great amount of schizophrenic disorder might be related to the life style we tend to have in the urban environment (personal habits, social and physical environment). Although there used to be a fierce debate about causality (if the urban environment could cause psicoses) and selection (if people with higher risk of developing psychosis choose to move to such areas), recent studies have been pointing that is is more probable that there is an interaction genotype-environment. To those that have a particular combination of genes - a genetic predisposition - epigenetic alterations might activate the manifestation of schizophrenia.
The first studies to discuss this relation between the increase of psychosis and the area where individuals lived in a city were from the 1930's. Robert Faris and Warren Durham, for instance, compared different socio-economic areas in Chicago and found that the highest concentration of schizophrenia cases were in central areas and that they diminished progressively the further away from the center they got, with the exception of a few deteriorated peripheral areas . But during the time of this study, the scientific community was more prone to the selection hypothesis, considering that people more susceptible to develop such mental disorders would choose to live in central areas.
In the 1990's, however, researchers from different localities studied this same issue and, this time, the techniques chosen allowed them to question the predominant belief regarding the selection hypothesis. Studies in Sweden and Denmark, for instance, focused in "place of birth" and "place of growing up" instead of "place of living". In both cases, they compared urbanised areas with rural areas . And the results were similar to those from Faris and Dunham: there is a clear relation between the incidence of such disorders and the level of urbanisation of a neighbourhood. These mentioned studies confirm that the number of people who develop psychosis such as schizophrenia is proportionally higher in more urbanised cities than in rural areas.
There is still a lot of discussions about epigenetics and how the external environment can influence the development of disorders. Although we do not have all the answers yet, the several studies conducted over the last decades have been pointing some specific qualities from the urban environment that might affect our gene expression. The two main ones are urbanity and population density . When we discuss hypothesis such as the biophilia, it makes a lot of sense to believe that urbanity might have deep effects in our organism. The same works for population density, as discussed in our article What NeuroUrbanism Teaches us About our Cities.
It is worth to mention two important points related to epigenetics: firstly, it does not involve any changes in DNA sequence. The combination of genes is still the same throughout our lives, what changes is how individual genes are expressed - they can be activated or not depending on how they are stimulated. Secondly, the environment can only impact genes that are already present in our genotype. This means that in order to develop anything, the combination of gene responsible for that must be present in our DNA. In the case of schizophrenia, without the genetic predisposition, an individual will not develop it no matter the environment where he is.
Although this debate still exists and that we need more studies to help to support and explain this hypothesis, the existing studies point to a direction that cannot be ignored by architects, designers and urban planners: the environment can influence our genes. Besides, there are even more recent areas of research such as transgerational epigenetics, pointing to the possibility of passing some of such alterations to the next generations. Are the spaces we design affecting not only their users but also their children? This is a very complex discussion and, although we do not have clear answers yet, we will be back to discuss it in a future article!
 Speybroeck, L. (2002) From Epigenesis to Epigenetics. Annals of the New York Academy of Sciences. Volume981, Issue1
 Farris, R., Dunham, HW. (1939) Mental Disorders in Urban Areas. Review by: James S. Plant. American Journal of Sociology, Vol. 44, No. 6 (May, 1939), pp. 999-1001
 Mortensen, PB, Pedersen, CB, Westergaard, T., Wohlfahrt, J., Ewald, H., Mors, O., Andersen PK., Melbye, M. (1999) Effects of Family History and Place and Season of Birth on the Risk of Schizophrenia. Boston Medical and Surgical Journal1999 / 02 Vol. 340; Iss. 8
 Krabbendam, L. e van Os, J. (2005) Schizophrenia and urbanicity: a major environmental influence--conditional on genetic risk. Schizophr Bull. 2005 Oct;31(4):795-9.