Green Cities – Part II: Cognitive Function & Mental Illness


Last month, in Part I of this series, I introduced you to a fascinating article about how interaction with nature can help alleviate mental fatigue and relax and restore the mind.

nature experiences are important for child development
nature experiences are important for child development

Part II of this study deals with how interaction with the out of doors and how brining nature into the work environment can positively impact workers performance. It will also present how a person’s response to nature can positively impact children with Attention Deficit Disorder (ADD) and individuals suffering from Alzheimers and Dementia.

I have always believed that humans have a deep and perhaps genetic need to interact with nature, which, I’m sure, is why I love what I do. This study demonstrates quite clearly how important that connection is to our physical and mental well being.

Published by the College of the Environment, University of Washington, the project’s support was provided by the national Urban and Community Forestry program of the USDA Forest Service, State and Private Forestry. Summary prepared by Kathleen Wolf, Ph.D. and Katrina Flora, December 26, 2010. You can read it in its entirety at

Cognitive Function


Office workers may spend entire days indoors, and many decorate their workspaces with plants or pictures of natural settings to compensate for lack of a window view. In one study, people in windowless workspaces introduced twice as many nature elements to their work area as those who had window views of natural areas.

a green office is a healthy and productive one
a green office is a healthy and productive one

Office workers report that plants make for more attractive, pleasant, and healthy work environments, but what impact do plants and nature views have on work performance? Studies show improved employee morale, decreased absenteeism, and increased worker efficiency result from such workplace enhancements. Having plants within view of workstations decreases both illness incidence, and the amount of self-reported sick leave. One study found that workers with workstation views that included green elements were more satisfied at work and had more patience, less frustration, increased enthusiasm for work, and fewer health problems. Not having nature views or indoor plants are associated with higher levels of tension and anxiety in office workers.

College Settings

green is an aid to learning and cognition
green is an aid to learning and cognition

Learning, like tasks at work, requires focused, direct attention and high-level cognitive functioning. When plants were added to a college computer lab, the study participants were more productive (with 12% quicker reaction times on tested computer tasks) and showed less stress—though there was no difference in number of errors made on the test. Additionally, participants reported feeling more attentive and better able to concentrate in the presence of plants. In other studies, participants performed better on creative tasks in rooms having foliage plants, versus those without, and the authors conclude that nature may provide inspiration and a source of stimulation for creativity. College students with more natural views from their dorm windows scored higher on tests of capacity to direct attention (CDA) and rated themselves as able to function more effectively. In another study of college students, those who participated in a nature walk performed higher on a subsequent CDA test than those who went on an urban walk or relaxed in a comfortable room with magazines and light music prior to the test.


nature experience are important for child development
nature experiences are important for child development

In recent times, children have less opportunity to be outdoors, in terms of both time and space. Some schools provide nature experiences as part of a class, recess, or special activity, as they recognize the potentially significant affects on learning and mental health.

Educational theory suggests that contact with nature facilitates children’s development of cognitive, emotional, and spiritual connections to social and biophysical environments around them. Ecological theory also suggests that contact with nature is important for children’s mental, emotional, and social health because imagination and creativity, cognitive and intellectual development, and social relationships are encouraged in outdoor activity, all of which improve the child’s mental health and function.

Nature can provide both background and objects for play and learning. Among older children, exposure to nature encourages exploration and building activities, which can improve problem-solving abilities, ability to respond to changing contexts, as well as participation in group decision-making. Younger children often use outdoor settings having plants, stones, and sticks as props for imaginative play, which is key to social and cognitive development. One study of children’s play found that a cluster of shrubs was the most popular place to play on an elementary schoolyard because it could be transformed into many imaginary places: a house, spaceship, etc.

Mental Illness and Nature Response

Attention Deficit Disorder (ADD)

many hospitals have healing gardens to serve patients and staff
many hospitals have healing gardens to serve patients and staffheali

Over 2 million children in the U.S. have been diagnosed with Attention Deficit Disorder (ADD), a condition that has detrimental effects on social, cognitive, and psychological growth. Studies show that childhood ADD symptoms can be reduced through activities in green settings and that “green time” may be an important supplement to established drug-based and behavioral treatments. In one study, the greenness of a child’s home did not significantly affect ADD symptom severity, but greenness of play setting was related to a reduction of symptom severity. Children who played in windowless indoor settings had significantly more severe symptoms than those who played in grassy, outdoor spaces with or without trees.

In another study, children diagnosed with Attention Deficit Hyperactivity Disorder (ADHD) performed better on an objective concentration test after exposure to a relatively natural urban setting as compared to a less natural urban setting. Children with ADD can benefit from spending more time in green settings on a daily basis, and during attention demanding activities (like school and homework). Providing nature experiences in the school day and class environment is important for all children, and particularly so for those with ADD.

Alzheimers and Dementia

Nature experiences provide mental health benefits for the elderly as well, including Alzheimer’s patients. Alzheimers is a type of dementia that causes memory impairment, intellectual decline, temporal and spatial disorientation, impaired ability to communicate and make logical decisions, and decreased tolerance to high and moderate levels of stimulation. Certain environments can provide prosthetic support for dementia patients to compensate for their reduced cognitive capabilities.

For example, spaces that have dead-ends or are crowded can increase frustration and anxiety in Alzheimer’s-diagnosed residents. Supportive outdoor spaces include these design features: looped pathways; tree groves or sites to act as landmarks for orientation; non-toxic plants; even, well-lit paths with handrails; seating areas with the suggestion of privacy; and use of low-key fragrances and colors to soothe, rather than negatively stimulate, the patient.

Studies have found that nature experiences can be of particular benefit to dementia patients. Exposure to gardens can improve quality of life and function of dementia patients by reducing negative behaviors up to 19%. Those patients who have access to gardens that are designed to positively stimulate the senses and promote positive memories and emotions are less likely to express negative reactions and fits of anger. After gardening activities, dementia and stroke patients exhibited improved mobility and dexterity, increased confidence, and improved social skills. Better sleep patterns, improved hormone balance, and decreased agitation and aggressive behavior have all been observed in dementia patients in association with contact with nature and the outdoors.

Cognition and Illness

Clinical reports have noted the loss of concentration and distractibility in patients experiencing serious illness. Studies have tested the correlation between stress and cognitive function under various conditions in women diagnosed with breast cancer. The impairment of CDA has been observed to set in before the start of a cancer treatment, suggesting that attentional fatigue has an early onset and is a result of the diagnosis itself. This is likely due to the mentally demanding and stressful nature of diagnostic tests and treatment planning. Participation in activities and/or interacting with natural environments was shown to ameliorate and help stave off mental fatigue both before and after breast cancer treatment or surgery.

Stress Relief

In addition to physiological symptoms, stress can lead to depression, schizophrenia, anxiety, exhaustion, and fatigue syndromes. Stress can occur at any time in life; however, such responses are especially prominent at later age due to physical, psychological, and social changes—for example, in response to chronic disease, disability, death of loved ones, or financial hardship. Stress can also negatively affect people’s perceptions of their well-being, including a poor perception of their own mental health. Physical activity has been linked to improvements in mental health and stress; many studies connect urban park use to decreased stress levels and improved moods. In one study, the longer participants stayed in a park, the less stress they exhibited. More than 100 studies have shown that relaxation and stress reduction are significant benefits associated with spending time in green areas.


Depression also occurs at any age and can be helped through improved social connections (to decrease the feeling of isolation) and exercise, both of which are promoted by having nearby green outdoor spaces. In one study, 71% of people found a reduction in depression after going on an outdoor walk versus a 45% reduction by those who went on an indoor walk. Another study investigated major depression disorder (MDD) and found that an exercise program can be just as effective as antidepressants in reducing depression among patients. The value of green spaces in encouraging exercise is relevant to treating depression symptoms.

To be continued …


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