Cognitive decline is a growing public health concern that affects millions of people around the world. Amid an aging population, strategies that help prevent or mitigate cognitive deterioration become increasingly relevant to support healthy aging and maintaining independence for longer. Studies in the field of neuroscience applied to architecture (neuroarchitecture) have shown that the physical environment, both internal and external, public and private, plays a fundamental role in this aspect [1]. In this sense, architects and urban planners can direct their projects to create solutions that significantly contribute to this objective.
The human brain is a very plastic organ. In other words, it transforms functionally and structurally according to how it is stimulated. Although this plasticity is much more intense during the development period, it continues to exist throughout our lives [2,3]. Therefore, keeping the brain stimulated during adulthood and aging is key to keeping cognition functioning at its best. In this context, recent studies indicate that certain stimuli help in the development of a cognitive reserve [4]. This, in turn, is the brain's resilience capacity, which helps it to remain functional even throughout aging and even when some neurodegenerative diseases arise [5].
Returning to architecture and urbanism, the spaces we occupy throughout development and throughout adult life influence the development of this cognitive reserve and can encourage its advancement or, on the contrary, discourage it. Therefore, seeking to understand what neuroscience has already investigated about how environments affect cognitive reserve and discussing the best strategies for creating healthier spaces is an important step.
It is worth highlighting that the idea is not to list a series of rigid guidelines for architects to follow, but rather to understand the complexity of the issue and what environments should offer their users, always taking into account the specific context of each typology of space, its location, and the culture and specific needs of the different user groups. The various studies on cognitive reserve point to the role of experience in its development [4]. In this sense, strategies for architecture and urbanism are much more focused on the experiences that the environment enables – called affordances by psychologist James Gibson – than on rules on how to create them. They are:
Opportunities for physical activity
The practice of physical activity is a key element in encouraging brain plasticity and, consequently, in the development of the cognitive reserve. Studies indicate that walking and movement significantly stimulate better memory functioning; the creation of new connections between neurons or strengthening of the existing ones; neurogenesis - the creation of new neurons in the hippocampus - and the production of neurotrophic factors - substances that protect neurons so that they can be healthy and functional for longer [6,7,8].
Urban and architectural design can encourage healthier and more active habits in cities and buildings. Elements such as safety for pedestrians and cyclists, wide and accessible sidewalks, protected bike lanes, and tree-lined spaces make places more inviting for walking and practicing physical activities. Furthermore, strategies such as taking care of the appearance of stairs and ramps, arranging stopping points, and creating well-planned routes also contribute to promoting a more active lifestyle. Organized layout and appropriate signage facilitate orientation and encourage people to explore spaces, which increases overall physical activity.
Social connection
Social connection is a broad concept that encompasses the structure, function, and quality of personal relationships and plays a fundamental role in mitigating cognitive decline. Studies indicate that people who consistently engage in a diversity of social domains tend to have slowed cognitive decline compared to lonelier people [9,10,11].
Design and architecture play an important role in creating opportunities for social connections.
Spaces with greater integration and visibility, such as atriums and squares, facilitate the identification of acquaintances and promote spontaneous meetings. Strategies that encourage space exploration, such as safety, wayfinding, and layout organization, also encourage these encounters. Furthermore, the creation of meeting spaces with different atmospheres and purposes enriches the possibilities for social exchanges and interactions, whether through more intimate or relaxed environments, which promote different qualities of connection.
Good quality sleep
Sleep is an essential physiological state for the proper functioning of the organism as a whole, and a series of brain functions occur exactly throughout the sleep period. For example, it is during this period that the toxins that accumulate throughout the waking period are removed from the brain, which is essential for maintaining proper functioning and brain health [12]. Furthermore, it is also during this period that memories and learning are consolidated and brain plasticity is promoted [13,14].
Therefore, environments for resting must provide adequate conditions to maintain good sleep duration and quality [15]. In this sense, two of the major environmental factors that deserve to be highlighted because they harm the quality of sleep are noise pollution and light pollution.
To ensure good quality sleep, the architecture of sleeping spaces, such as residential, hospital or hotel rooms must focus on reducing environmental noise, especially that coming from means of transport and areas close to the room. Isolating external noise, as well as internal noise from the building itself and equipment in the room, is essential. Furthermore, lighting plays a key role in regulating the sleep-wake cycle. Bedrooms should be dark at night, with windows equipped with good blackouts to prevent city light from entering. When lights are necessary, they should be positioned out of the bed occupant's field of vision and chosen based on the amount of blue light emitted, as blue light can negatively interfere with the sleep cycle. More yellowish or orange lights are more suitable for nighttime environments.
Cognitive challenges: novelty and wayfinding
One of the best exercises to keep your brain healthy for longer is to frequently seek new cognitive challenges. Learning to speak a new language, or to play a new instrument, or to dance a new rhythm, etc., are examples of important challenges for the brain throughout life. In addition to these examples, the environment can be a source of healthy stimuli for cognition through its architecture and design.
The hippocampus, a brain region involved, among other things, with the processing of long-term memories, is also a highly active area involved with navigation and spatial orientation processes. Studies indicate that when we navigate new routes, this area of the brain ends up being greatly stimulated, just like when we exercise our memory. It is worth noting that this is one of the areas of the brain most sensitive to aging and, in most cases, it is the first in which it is possible to identify Alzheimer's damage. That's why it's so important to exercise it throughout our lives. To give you an idea, a study with taxi drivers in London - who navigate a complex space along different routes and to different destinations - observed a greater volume of the hippocampus in taxi drivers than in bus drivers in the same city - who always navigate the same route and, consequently exercise the hippocampus less with these activities [16].
In cities and complex buildings, creating inviting and varied routes, with tree-lined streets, wide sidewalks, and bike lanes, and a comprehensive layout encourages navigation without GPS, promoting the exercise of cognition and physical activity, and contributing to the development of cognitive reserve. Furthermore, providing landmarks and distinct multisensory stimuli in indoor and outdoor environments helps with navigation and memorization, highlighting the identity of each space through smells, sounds, colors, textures, and symbols associated with each location. These strategies encourage active exploration and enrich the experience, stimulating the mind and body.
Chronic stress management
Finally, one of the greatest enemies of mental health which harms the creation of cognitive reserve is chronic stress. Several studies indicate that high levels of stress, in the long term, impair learning and memory [17,18]; encourage the loss and atrophy of hippocampal neurons [19,20,21] and decrease neurogenesis [22,23].
Therefore, an architecture that helps us combat this problem is essential in supporting healthy aging. Active design, which encourages people to practice more physical activity simply through the use of architectural elements, such as a staircase or a ramp instead of an elevator, for example, is a very efficient strategy for combating chronic stress and its negative effects. However, there are other important solutions that can be combined with active design to create spaces that are even healthier and more efficient in combating stress. For example, biophilic design strategies that encourage positive contact with nature have proven to be quite efficient in this regard. Taking care of acoustic comfort also helps eliminate one of the characteristics that most increase chronic stress levels from the environment: noise pollution. Furthermore, solutions that provide more privacy and spaces of refuge, where people can relax and recover some energy in a stressful day, are also good allies to combat stress. These are welcome in all types of spaces, from public areas in the city to environments such as offices, hospitals, schools, and even at home.
As we mentioned at the beginning, in the midst of an aging population, it is necessary to think and plan strategies to prevent or mitigate cognitive decline, enabling people to remain independent and with a better quality of life for longer. Both architecture, urbanism, and interior design play an extremely relevant role in this, which is often neglected or unknown. It is imperative that we change this reality as soon as possible. Building a cognitive reserve, which strengthens resilience and brain health, does not begin later in the aging process; on the contrary, its cultivation takes place from development and throughout adulthood. That's why we need to rethink the environments we create not only for the elderly but also for children and young adults, bringing a series of combined strategies to support the development of the cognitive reserve throughout the lifespan. Ultimately, by adopting a conscious and holistic approach to spatial design, far beyond just designing spaces to house the various activities of everyday life, we will promote, through these spaces, solid foundations for a healthier, more inclusive, and resilient society throughout all stages of life.
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References
[1] De Paiva, A. & Jedon, R. (2019) Short- and long-term effects of architecture on the brain: toward theoretical formalization. Frontiers of Architectural Research, Volume 8, Issue 4, 564-571
[2] Diamond, M. C., Krech, D., & Rosenzweig, M. R. (1964). The Effects Of An Enriched Environment On The Histology Of The Rat Cerebral Cortex. The Journal of Comparative Neurology, 123, 111–120.
[3] Rosenzweig, M. R., Krech, D., Bennett, E. L., & Diamond, M. C. (1962). Effects of environmental complexity and training on brain chemistry and anatomy: a replication and extension. Journal of comparative and physiological psychology, 55, 429–437.
[4] Mandolesi, L., Gelfo, F., Serra, L., Montuori, S., Polverino, A., Curcio, G., & Sorrentino, G. (2017). Environmental Factors Promoting Neural Plasticity: Insights from Animal and Human Studies. Neural plasticity, 2017, 7219461.
[5] Snowdon, D. A. Nun Study (2003). Healthy aging and dementia: findings from the Nun Study. Annals of Internal Medicine, 139(5 Pt 2), 450–454.
[6] van Praag, H., Shubert, T., Zhao, C., & Gage, F. H. (2005). Exercise enhances learning and hippocampal neurogenesis in aged mice. The Journal of neuroscience: the official journal of the Society for Neuroscience, 25(38), 8680–8685.
[7] van Praag H. (2009). Exercise and the brain: something to chew on. Trends in neurosciences, 32(5), 283–290.
[8] Vivar, C., Potter, M. C., & van Praag, H. (2013). All about running: synaptic plasticity, growth factors, and adult hippocampal neurogenesis. Current topics in behavioral neurosciences, 15, 189–210. https://doi.org/10.1007/7854_2012_220
[9] Piolatto, M., Bianchi, F., Rota, M., Marengoni, A., Akbaritabar, A., & Squazzoni, F. (2022). The effect of social relationships on cognitive decline in older adults: an updated systematic review and meta-analysis of longitudinal cohort studies. BMC Public Health, 22(1), 278.
[10] Roth A. R. (2022). Social connectedness and cognitive decline. The Lancet. Healthy longevity, 3(11), e723–e724.
[11] Samtani, S., Mahalingam, G., Lam, B. C. P., Lipnicki, D. M., Lima-Costa, M. F., Blay, S. L., Castro-Costa, E., Shifu, X., Guerchet, M., Preux, P. M., Gbessemehlan, A., Skoog, I., Najar, J., Rydberg Sterner, T., Scarmeas, N., Kim, K. W., Riedel-Heller, S., Röhr, S., Pabst, A., Shahar, S., … SHARED consortium for the Cohort Studies of Memory in an International Consortium (COSMIC) (2022). Associations between social connections and cognition: a global collaborative individual participant data meta-analysis. The Lancet. Healthy longevity, 3(11), e740–e753.
[12] Xie, L., Kang, H., Xu, Q., Chen, M. J., Liao, Y., Thiyagarajan, M., O'Donnell, J., Christensen, D. J., Nicholson, C., Iliff, J. J., Takano, T., Deane, R., & Nedergaard, M. (2013). Sleep drives metabolite clearance from the adult brain. Science (New York, N.Y.), 342(6156), 373–377.
[13] Tamaki, M., Wang, Z., Barnes-Diana, T., Guo, D., Berard, A. V., Walsh, E., Watanabe, T., & Sasaki, Y. (2020). Complementary contributions of non-REM and REM sleep to visual learning. Nature Neuroscience, 23(9), 1150–1156.
[14] Weiss, J. T., & Donlea, J. M. (2022). Roles for Sleep in Neural and Behavioral Plasticity: Reviewing Variation in the Consequences of Sleep Loss. Frontiers in behavioral neuroscience, 15, 777799.
[15] Halperin D. (2014). Environmental noise and sleep disturbances: A threat to health? Sleep science (Sao Paulo, Brazil), 7(4), 209–212. https://doi.org/10.1016/j.slsci.2014.11.003
[16] Maguire, E. A., Woollett, K., & Spiers, H. J. (2006). London taxi drivers and bus drivers: A structural MRI and neuropsychological analysis. Hippocampus, 16(12), 1091-1101. doi:10.1002/hipo.20233
[17] Cahill, L., & McGaugh, J. L. (1998). Mechanisms of emotional arousal and lasting declarative memory. Trends in neurosciences, 21(7), 294–299.
[18] Kim, J. J., & Diamond, D. M. (2002). The stressed hippocampus, synaptic plasticity, and lost memories. Nature reviews. Neuroscience, 3(6), 453–462. https://doi.org/10.1038/nrn849
[19] McEwen, B. S., & Sapolsky, R. M. (1995). Stress and cognitive function. Current opinion in neurobiology, 5(2), 205–216. https://doi.org/10.1016/0959-4388(95)80028-x
[20] Vyas, A., Mitra, R., Shankaranarayana Rao, B. S., & Chattarji, S. (2002). Chronic stress induces contrasting patterns of dendritic remodeling in hippocampal and amygdaloid neurons. The Journal of neuroscience: the official journal of the Society for Neuroscience, 22(15), 6810–6818.
[21] Woolley, C. S., Gould, E., & McEwen, B. S. (1990). Exposure to excess glucocorticoids alters the dendritic morphology of adult hippocampal pyramidal neurons. Brain Research, 531(1-2), 225–231.
[22] Duman, R. S., Malberg, J., & Nakagawa, S. (2001). Regulation of adult neurogenesis by psychotropic drugs and stress. The Journal of pharmacology and experimental therapeutics, 299(2), 401–407.
[23] Malberg, J. E., & Duman, R. S. (2003). Cell proliferation in the adult hippocampus is decreased by inescapable stress: reversal by fluoxetine treatment. Neuropsychopharmacology: official publication of the American College of Neuropsychopharmacology, 28(9), 1562–1571.
