Depression is about to edge out HIV/AIDS as the world's most significant health problem according to the World Health Organization. Why does depression stalk the world's cities?
If we knew the answer to this simple question, we would be well on the way to preventing this devastating disorder instead of having to rely upon antidepressant medicines that have troubling side effects and are minimally effective.
The evidence for an epidemic of depression is very clear and has been heavily discussed in the clinical literature. For Americans born a century ago, the chances of suffering any episode of major depression in the lifetime was only about 1 percent. Today, the lifetime incidence is 19.2 percent (1). This implies a relative increase of some 2,000 percent. Yet, even that estimate understates the problem because depression is becoming more prevalent in the young and is striking at ever-younger ages. Similar patterns are reported in other countries.
We do not know exactly why depression is such a bane of modern life. One way of winnowing out possible causes is to look for psychological advantages of living on a subsistence farm compared to city life.
Why the farmer used to be happy
If you want to hear a grown man cry, go talk to a farmer!
This witticism reflects problems of family farms in the age of agribusiness. Farming has become a difficult and uncertain occupation exposed to the vagaries of worldwide commodity prices and subject to whimsical government regulation and the constant threat of bankruptcy. Despite being otherwise healthier than the general public, farmers suffer more from anxiety and depression (2).
Yet, when most Americans lived on farms a century ago, there was almost no depression. Why were subsistence farmers so cheerful? Possible reasons range from exercise and contact with the soil to social cohesion.
Farmers did a great deal of manual labor and physical activity is a natural anti-depressant (3). Inactivity is a key symptom of depression so physical work directly counteracts the symptom counteracting the neurochemical profile of the disease as well.
Thanks to their high activity level, and high-fiber diet, subsistence farmers were slender which means that they did not suffer much from diabetes, heart disease, or the other obesity-related problems that are the bane of modern life.
People who suffer from depression are at a greater risk of heart disease and both are linked to inflammation (4), a process in which the immune system attacks pathogens. Both stress and obesity activate inflammatory processes. Modern conditions that cause obesity and heart disease may also cause depression and subsistence farmers were mostly free of these conditions.
Being part of a stable local community protected farmers against depression as opposed to the more anonymous conditions of urban life where social isolation is more likely. In subsistence communities, families were large and people knew their neighbors well. Subsistence farmers were more active in their religions–another form of social support that could reduce depression.
Although their lifestyle was humble, farmers could satisfy all of their basic needs and their economic lives were generally more predictable and controllable than those of modern workers who live in fear of losing their jobs. They were, however vulnerable to rare extreme weather events.
The process of caring for livestock, and even plants, may be psychologically soothing and English prisoners active in gardening programs fare much better than other inmates as dramatized in the British movie Greenfingers (2000). Likewise residents of nursing homes lived longer themselves when given a plant to care for (5).
Modern farmers trade soybean futures from their tractor cabs. Subsistence farmers were deprived of novel information. That made their lives tedious but it may have protected them from depression. Recent research suggests that exposure to TV increases anxiety and depression as we experience the traumas of other people around the globe or feel inadequate relative to ideals of beauty and success depicted there (6).
Perhaps the most tantalizing reason for minimal depression in subsistence farmers is the notion that physical contact with the soil relieves depression. Soil microbes are believed to interact with the immune system in ways that boost neurotransmitters that are deficient in depression (7). This–admittedly strange–idea is supported by ongoing research.
Modern farmers may have a lot to cry about but subsistence farmers were much jollier. If we could understand why depression was so low in subsistence farmers we would know why depression stalks the cities today.
1. Bromet, E. et al. (2011). Cross-national epidemiology of DSM-IV major depressive episode. BMC Medicine, 9: 90. accessed at: http://www.biomedcentral.com/1731-7015/9/90
2. Sanne, B. et al. (2004). Farmers are at risk for anxiety and depression: The Hortaland Health Study. Occupational Medicine, 54, 92-100.
3. Strathopoulou, G. et al. (2006). Exercise interventions for mental health: A quantitative and qualitative review. Clinical Psychology: Science and Practice, 13, 178-193.
4. Raison, C. L. et al. (2010). Inflammation, sanitation, and consternation. Archives of General Psychiatry, 67, 1211-1224.
5. Rodin, J., & Langer, E. (1977). Long-term effects of a control-relevant intervention with the institutionalized aged. Journla of Personality and Social Psychology, 35, 897-902.
6. Primack, B. A. et al. (2009). Association between media use in adolescence and depression in young adulthood: A longitudinal study. Atchives of General Psychiatry, 66, 181-188.
7. Lowry, C. A., et al. (2007). Identification of an immune-responsive mesolimbocortical serotonergic system: Potential role in regulation of emotional behavior. Neuroscience, 146, 756-772.