Investigating effects of day-to-day variations in environmental exposure on the human brain: the Day2Day Environment project

Background: Understanding how daily environmental exposures influence the human brain and mental health is increasingly important in the context of global urbanization and climate change. Previous studies have focused primarily on long-term environmental factors or isolated features like green space and air quality, neglecting the interaction between multiple exposures encountered in everyday life. This protocol paper describes the study design and dataset of the Day2Day Environment project, an ongoing study investigating how real-world, day-to-day environmental variability affects brain structure, function, and well-being.Methods: This longitudinal study collects multimodal data from 30 participants over 25 testing sessions, including neuroimaging and tracking of physiological, behavioral, and environmental variables. Using wearable devices, geographic ecological momentary assessments, and GPS-based geospatial tracking, we collect data on air quality, noise, light exposure, physical activity, stress, cognition, and affect. Neuroimaging measures include T1- and T2*-weighted images during rest and tasks, quantitative multi-parameter mapping, high-resolution proton density imaging of the hippocampus, and diffusion tensor imaging sequences.Conclusion: The Day2Day Environment dataset offers a unique opportunity to study short-term neuroplasticity in response to the dynamic interplay between multiple environmental exposures. Furthermore, the diversity of measurements in this dataset may be valuable for addressing research questions beyond environmental neuroscience.