Measuring Snot to Test a Feeling
In the early 2000s, a team led by Sheldon Cohen at Carnegie Mellon University in Pittsburgh, Pennsylvania, did something that sounds less like medicine and more like a dare. [1] They recruited 334 volunteers willing to have a common cold virus dripped into their noses. [1] The point was not cruelty. The point was to replace guesswork with measurement.
Until then, the link between mood and illness had mostly been calculated from what people reported feeling. Here was a way to observe infection directly: quarantine each volunteer for five days, then weigh the used tissues to estimate mucus production. That is not a metaphor. The researchers literally collected and weighed the snotty tissues.
Before infection day, each participant had filled out regular questionnaires for a month, logging emotions both positive — cheerful, at ease, energetic — and negative — sad, on edge, hostile. Then came the nasal drop, containing one of two rhinoviruses known to cause sniffles.
The result was not subtle. People with a sunnier emotional style were about a third less likely to develop symptoms than those who were less positive. [1] And here is the part that surprises: the effect of positive feelings was independent of negative feelings. Someone who felt both cheerful and anxious still did better than someone who felt neither. Two emotions can share the same mind at the same time, and the cheerful one appears to carry more weight for health.
Teaching the Mind to Shield the Body
Confirming a pattern is one thing. Changing it is another.
Like the earlier work, it did not rely on self-reported symptoms alone. It looked for objective evidence of infection through blood tests, cheek swabs and nasal washes.
The participants who practiced mindfulness were generally less likely to develop a respiratory illness. Those who did show signs of infection had milder symptoms.
Symptoms like a runny nose track directly with levels of IL-6, a pro-inflammatory signalling protein called a cytokine. Among people with a positive emotional style, that level was much lower after infection. [2] The same story holds for a different cytokine. A group led by Sara Puig Pérez at Valencian National University, Spain, found that optimists carry lower levels of TNFα — another pro-inflammatory cytokine linked to the fatigue and lethargy that come with the sniffles. [2] Fewer symptoms followed.
Sources
- DOI: 10.1097/01.psy.0000077508.57784.da
- DOI: 10.1097/01.psy.0000245867.92364.3c
- Newscientist — Quote source (original article)