Regional prevalence of fatiguing illnesses in the United States before and after the terrorist attacks of September 11, 2001.

OBJECTIVE Stress or emotional traumas are considered risk factors for unexplained fatiguing illnesses. From July to December 2001, the Centers for Disease Control and Prevention conducted a multigeographical pilot study to test the feasibility of a survey to estimate the prevalence of fatiguing illnesses in the United States. We used data obtained during this survey to estimate the effect of the coincidentally occurring terrorist attacks of September 11, 2001, on the regional prevalence of fatiguing illnesses. METHODS Identified by random-digit dialing, 2,728 households in eight regional strata were interviewed, and 7,317 respondents were screened for severe fatigue of at least 1 month duration. Identified fatigued people of age 18 to 69 years (N = 440) and a sample of nonfatigued people of the same age range (N = 444) were interviewed in detail concerning fatigue, other symptoms, and medical and psychiatric histories. RESULTS Weighted prevalence estimates based on interviews performed after the attacks were significantly lower compared with estimates based on interviews performed before the attacks (prolonged fatigue: 5,450 vs. 1,530/100,000, p =.010; chronic fatigue: 18,510 vs. 10,070/100,000, p =.002; chronic fatigue syndrome-like illness: 2,510 vs. 960/100,000, p =.014). CONCLUSION Our findings suggest decreased regional prevalence of fatiguing illnesses in the aftermath of the terrorist attacks. The causes of this effect are unknown but might involve acute psychological and physiological adaptations that modify the perception or manifestation of fatigue. Future studies should be specifically designed to scrutinize the relationship between stress and fatiguing illnesses and the mediating mechanisms of such a relationship.