The National Institute of Allergy and Infectious Diseases estimates that each year, Americans suffer one billion ]]>colds]]> . And according to the National Center for Infectious Diseases, in 1996 (the last year for which data are available), 62 million cases of the common cold in the U.S. required medical attention or resulted in restricted activity. Children get the most colds at six to 10 a year; adults average about two to four a year.

Unfortunately, despite the abundance of the over-the-counter remedies available to battle symptoms, little can be done about a cold except to ride it out. Some researchers are hoping to develop a single vaccine for most types of colds (there are more than 200 different cold viruses). Others are looking into whether a person’s attitude affects his or her chances of catching a cold in the first place.

In a recent study published in the July 2003 issue of Psychosomatic Medicine, researchers compared how often people with either positive or negative emotions contract a cold. Their results indicated that those who are energetic, happy, and relaxed are less likely to catch colds, while those who are depressed, nervous, or angry are more likely to complain about symptoms—regardless of whether they actually have a cold. In fact, people with these negative attributes were more likely to report symptoms of illness that exceeded what one would expect from measures used by researchers.

About the Study

The researchers assessed the emotional style, demographic characteristics, levels of antibodies to cold-producing viruses, hormone levels, and health practices (smoking, drinking, exercise, sleep patterns, and dietary intake) of 334 volunteers aged 18 to 54 years, and then quarantined them for six days.

On the first day, participants were given nasal drops containing varying levels of one of two types of rhinovirus (the virus most commonly associated with cold symptoms). For the next five days, participants reported their respiratory symptoms and were evaluated for signs of cold (for example, nasal mucus production). Nasal lavage (fluid) samples were collected for virus culture. Participants were considered to have a cold if they both:

  1. Were infected – either the virus was recovered from the participant on any of the five days following exposure or the participant had a significant increase in viral antibodies.
  2. Were ill – showed increased mucus production, respiratory symptoms, and other signs suggestive of a cold.

To measure emotional style, researchers interviewed participants on several occasions prior to quarantine and on the first evening of quarantine. They were asked how accurately each of nine positive adjectives (lively, full-of-pep, energetic, happy, pleased, cheerful, at ease, calm, and relaxed) and nine negative adjectives (sad, depressed, unhappy, on edge, nervous, tense, hostile, resentful, and angry) described how they felt the previous day.

The Findings

The researchers found that even after taking into account differences in pre-exposure antibody level, demographics, season, virus type, and other relevant factors, an increase in positive emotional style (PES) was significantly associated with a decreased rate of clinical colds among infected participants. A PES had no effect on how often participants were infected, but rather increased a person’s resistance to illness (it produced fewer signs and symptoms of illness).

However, a negative emotional style (NES) had no effect on the incidence of colds. Instead, NES predicted greater reporting of “unfounded” symptoms (those that were independent of objective markers of disease used by researchers).

Further analysis revealed that PES was associated with better health practices and lower levels of catecholamines and cortisol (stress-related hormones). But these variables could not account for why more positive people were less likely to catch a cold. It is possible that factors not considered (such as genetics or other personality characteristics) might explain higher PES and resistance to infection.

How Does This Affect You?

This study suggests that people who have positive emotions are less likely to get sick than others. Though it is not clear that a “a smile a day could keep the doctor away,” reducing the risk of developing a cold by enhancing positive emotion and perhaps developing a psychological risk profile (i.e., a way for physicians to assess the mood of their patients) seems reasonable—especially when you consider how common colds are. What remains unclear from this study is whether or not changing your emotional style can affect your risk of a catching a cold.

Although these researchers chose the common cold to study the effects of emotional attributes on illness, it would also be interesting, and perhaps more valuable, to learn the effects of personality and life views on more serious infections and diseases. To date, such studies have had mixed results.