Original title: Spend time outdoors for your brain – an in-depth longitudinal MRI study

Authors: Kühn, Simone; Mascherek, Anna; Filevich, Elisa; Lisofsky, Nina; Becker, Maxi; Butler, Oisin; Lochstet, Martyna; Mårtensson, Johan; Wenger, Elisabeth; Lindenberger, Ulman; Gallinat, Jürgen

Lise Meitner Group for Environmental Neuroscience, Max Planck Institute for Human Development, Berlin, Germany; Clinic and Polyclinic for Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany

Quelle: https://doi.org/10.1080/15622975.2021.1938670

Note: This scientific study is freely accessible to everyone and has been translated into German by me. The emphasis is mine.

What was the study about?

It was investigated whether there is a connection between spending time outdoors and the structural plasticity of the brain in connection with self-reported emotions.

“Our results show that our brain structure and mood improve when we spend time outdoors. It can be assumed that this also has an effect on concentration, working memory and the psyche as a whole. We are investigating this in an ongoing study in which the test subjects also have to solve mental tasks and wear numerous sensors that measure, for example, the amount of light they are exposed to during the day,” says Simone Kühn, head of the Lise-Meitner Environmental Neuroscience Group at the Max Planck Institute for Human Development and lead author of the study. Source: https://idw-online.de/de/news772875


  • A whole-brain analysis revealed that time spent outdoors was positively associated with gray matter volume in the right dorsolateral prefrontal cortex and positive affect
  • Most strikingly, and independent of affect, we observed that more hours spent outdoors were associated with higher gray matter volume in the right dorsolateral prefrontal cortex.
  • The results indicate a remarkable and potentially behaviorally relevant plasticity of the cerebral structure within a short time frame determined by the time spent outdoors each day.
  • This is compatible with anecdotal evidence for the health and mood-enhancing effects of walking.
  • Hours spent outdoors remained a significant predictor, but hours of free time and sunshine duration were also predictive of positive affect, while fluid intake and physical activity were not significant.
  • The study could provide the first evidence for underlying cerebral mechanisms of so-called green prescriptions, with possible implications for future interventions in mental disorders.
  • The fact that we found a change in gray matter in the DLPFC of the order of 3% is consistent with many experimental studies in which participants were exposed to interventions known to have a positive effect on the brain, such as physical exercise or cognitive training, in which the increases are typically 2-5% in gray matter volume. It is therefore remarkable that we find effects of similar magnitude in this more naturalistic study design that assesses daily variations.
  • One limitation of the present study is the small and selective sample. The participants had no excessive nicotine, alcohol or drug consumption, which excludes control of these variables.
  • In summary, this result underlines the importance of how and in which environment (indoors vs. outdoors) we spend our daily lives.
  • Since psychiatric disorders have been consistently associated with prefrontal structural deficits, so-called outdoor prescriptions could be a helpful means of counteracting these neuronal changes and improving mood.
  • Given the relevance of prefrontal functions in our society as a whole, interventions aimed at increasing time spent outdoors at the population level could be an interesting implication of the present results.

Further details:

  • Six drug-free, healthy people currently living in the city (aged 24-32 years, one man, all living in Berlin) were examined
  • The participants worked at the Max Planck Institute for Human Development
  • Most participants were scanned about twice a week, between summer 2013 and early 2014 over a period of 6- 8 months, totaling 40- 50 measurement points
  • The question was asked:
    • the self-reported time spent outdoors (“How much time have you spent outdoors in the last 24 hours? (in hours)
    • Fluid intake (“How much have you drunk in the last 24 hours? (in liters)
    • free time (“How much free time have you had in the last 24 hours? (in hours)
    • Amount of caffeinated drinks (“How many cups of caffeinated drinks have you drunk in the last 24 hours?
    • Amount of physical activity (‘How many hours of physical activity have you done in the last 24 hours?’ (in hours)
    • Questionnaire on momentary affect (Positive and Negative Affect Schedule, PANAS) (Watson et al. 1988)
    • Physical activity tracking device that measures the number of steps (Fitbit One, San Francisco, USA) on a daily basis
    • In order to record seasonal differences, the daily hours of sunshine were determined by the German Weather Service

Figure 1. (A) Illustration of data collected from a single subject, (B) Clusters in the dorsolateral prefrontal cortex (DLPFC) showing a positive association between gray matter probability and self-reported hours spent outdoors, and (C) for illustrative purposes only, we present a line graph showing the regression of each subject’s extracted gray matter values from the DLPFC (right), the y-axis has a fraction as indicated by the fraction symbol.