Chapter 153
Promoting Mental Health — 1
The complex interactions between our mental and physical health have never been fully broken down, and likely never will be, but there’s no question that they are interdependent. It is hard to see how we could extend health span without attention to both components. Just consider that, in experimental models and people, chronic stress has been shown to potentiate cancer and its spread. Or the evidence for a cause-and-effect relationship of mental health and healthy longevity. That’s why, from a population view, it’s more than sobering to see the current burden of mental health illness, affecting 21 percent, more than fifty million Americans.
One in four of those millions of Americans are unable to get the mental health care they need. That’s in part because there is only one mental health provider for every 350 individuals. This shortage of mental health care professionals has been steadily worsening over many years, accelerating during and since the COVID pandemic. In the 2024 World Happiness Report, the United States rank fell to twenty-third place, a drop from fifteenth the prior year. (The top four rankings were all countries in Scandinavia.) What will it take to get people less anxious, stressed, and depressed, and more upbeat and happier, with relatively few trained professionals to help?
We are going to get to the more technological initiatives we can take, but let’s first consider some things that aren’t talked about much in the medical profession.
We don’t spend nearly enough time outdoors in natural environments. The diverse health benefits that have been reported include lower blood pressure, improved sleep health, reduced risk of cardiovascular disease, improved cognitive function, better immune system response, reduced stress (with lower cortisol levels), and alleviation of symptoms of depression. A key mechanism that has been raised for the benefit of time in nature, and promotion of well-being, is activation of the olfactory pathway. Among nearly twenty thousand nationally representative participants, good health or high well-being was significantly greater with more than 120 minutes of exposure per week to nature, such as parks, woodlands, or beaches (fig. 11.1).
Amuch larger study from over four hundred thousand UK Biobank participants with twelve years of follow-up showed that long-term exposure to residential greenness was associated with a significant reduction of depression and anxiety (15 percent from highest to lowest quartile). Further analysis indicated that air pollution played a major role in this association. Less urban green exposure was assessed with functional MRI, identifying a neural risk factor of activation in the prefrontal cortex with impaired human emotional processing. Andreas Meyer-Lindenberg and colleagues at the University of Heidelberg concluded: “Our results validate the causal influence of urban green space exposure as a protective factor for human well-being in real life.”
Figure 11.1. Well-being and time in nature. Adapted from “Loneliness and social isolation linked to serious health conditions,” Centers for Disease Control and Prevention, April 29, 2021, https://www.cdc.gov/aging/publications/features/lonely-older-adults.html.
That’s just scratching the surface for the body of evidence. An exhaustive review of green space exposure in more than 140 studies emphasized the benefit for reducing all-cause mortality and fewer physical and mental ailments. Now a NatureScore has been derived from aggregation of satellite images, air and noise pollution, open water, and trees to provide a high-resolution map across the United States, accessible through a smartphone app. There is marked variability in the score across the country, ranging from approaching one hundred in Suffolk, Virginia, to fewer than ten in Union City, New Jersey. You can get your local score here: https://www.naturequant.com/naturescore/. From the map, it is also clear that accessibility to nature is substantially reduced where people of low socioeconomic status live, exacerbating health inequities.