Incidence of Dementia before Age 65 Years among World Trade Center Attack Responders

Abstract

Importance: Reports suggest that the individuals who served in rescue operations following the terrorist attacks on the World Trade Center (WTC) have poorer brain health than expected. Objective: To assess the incidence of dementia before age 65 years in a prospective study of WTC responders and to compare incidence among responders with severe exposures to debris vs responders not exposed to building debris or who wore personalized protective equipment (PPE). Design, Setting, and Participants: This prospective cohort study was conducted from November 1, 2014, to January 1, 2023, in an academic medical monitoring program available to verified WTC responders residing on Long Island, New York. Responders 60 years of age or younger without dementia at the time of their first cognitive assessment were followed up every 18 months, on average, for up to 5 years. Exposures: Exposure severity was based on responses to a detailed questionnaire of WTC exposures and exposure-related activities that included exposures to fine particulate dust and potentially neurotoxic debris, duration of work, and the use of PPE. Exposure level was divided into 5 categories ranging from low to severe. Main Outcomes and Measures: Incidence of all-cause dementia before age 65 years was the primary outcome. Dementia was diagnosed following standard guidelines relying on repeated measures of cognition. Results: Of 9891 responders, 5010 were eligible for inclusion in this study of cognitive function (median [IQR] age, 53 [48-57] years; 4573 [91.3%] male). There were 228 cases of dementia identified during 15913.1 person-years of follow-up. Increasing WTC exposure severity was associated with incremental increases in the incidence rate of dementia per 1000 person-years (low, 2.95 [95% CI, 1.07-11.18]; mild, 12.16 [95% CI, 10.09-14.79]; moderate, 16.53 [95% CI, 13.30-20.81]; high, 30.09 [95% CI, 21.35-43.79]; and severe, 42.37 [95% CI, 24.86-78.24]). Adjusting for social, demographic, and relevant medical factors, each unit increase in exposure severity was associated with increased incidence of dementia (adjusted hazard ratio, 1.42 [95% CI, 1.18-1.71]; P