A thought-provoking post from A Paper a Day Keeps the Scientist Okay entitled “Living Near a Forest Keeps Your Amygdala Healthier” referenced a 2017 German human study which found:
“..a relationship between place of residence and brain health: those city dwellers living close to a forest were more likely to show indications of a physiologically healthy amygdala structure and were therefore presumably better able to cope with stress.”
The researchers accomplished the imperative of meeting the study’s stated objective:
“We set out to identify and characterize the geographical elements of a city that are associated with these brain structures following a suggestion by Kennedy and Adolph that studies should begin to derive recommendations for urban planning and architecture.
The results of our study may suggest that forests in and around the cities are a valuable resource that should be promoted. However future longitudinal studies are needed to investigate the causal directionality of the effect in order to disentangle whether more forest in ones habitat facilitates brain structural integrity or potentially those people with better brain structural integrity choose to live closer to forests. Moreover we need to investigate whether living close to the forest is associated with an absence of risk factors such as noise, air pollution or stress and thereby has beneficial effects or whether the forest itself constitutes a salutary factor that promotes well-being.”
A major limitation of the study’s methodology that wasn’t noted by the researchers was the intentional non-use of an available data source. Referring to Do we need to study the brain to understand the mind? posted earlier this week:
“Self-report is still the gold standard for assessing emotional experience and the contents of thought. Isn’t it easier just to ask?”
The researchers put the forest before the trees, and designed a study that didn’t ask the subjects important questions such as why they lived where they lived. The researchers inferred sketchy fMRI-geography associations because they didn’t solicit relevant primary information via individual self-reports.
I imagined myself as one of the study’s subjects. I don’t live in Berlin, and I’m not part of the selected cohort, but I otherwise generally meet the study’s subject parameters.
Something in my past causes me to actively select housing that isn’t in a noisy environment. If I were asked why I lived where I lived, my answer would have included:
- A deciding factor in why I sold my second house was the traffic noise in wintertime;
- A deciding factor in why I bought my fourth house was its location in the center of the housing development, away from street noise; and
- A deciding factor in why I live where I now live is the house’s orientation away from both direct and reflective traffic noise sources.
Processing my hypothetical fMRI data with my self-reported historical housing choices may or may not have found:
“Geographical features in the proximal participants’ habitat are associated with brain integrity.”
Using the better-quality information of self-reports, though, it’s unlikely that an association this study would have found to be significant – the chance fact that I live within one kilometer of a forest – would have been deemed significant.
https://www.nature.com/articles/s41598-017-12046-7 “In search of features that constitute an “enriched environment” in humans: Associations between geographical properties and brain structure”