Prevalence of Mild and Severe Cognitive Impairment in World Trade Center Exposed Fire Department of the City of New York (FDNY) and General Emergency Responders

Abstract

Background

The emergency personnel who responded to the World Trade Center (WTC) attacks endured severe occupational exposures, yet the prevalence of cognitive impairment remains unknown among WTC-exposed-FDNY-responders. The present study screened for mild and severe cognitive impairment in WTC-exposed FDNY responders using objective tests, compared prevalence rates to a cohort of non-FDNY WTC-exposed responders, and descriptively to meta-analytic estimates of MCI from global, community, and clinical populations.

Methods

A sample of WTC-exposed-FDNY responders (n = 343) was recruited to complete an extensive battery of cognitive, psychological, and physical tests. The prevalences of domain-specific impairments were estimated based on the results of norm-referenced tests, and the Montreal Cognitive Assessment (MoCA), Jak/Bondi criteria, Petersen criteria, and the National Institute on Aging and Alzheimer's Association (NIA-AA) criteria were used to diagnose MCI. NIA-AA criteria were also used to diagnose severe cognitive impairment. Generalized linear models and propensity score matching were used to compare prevalence estimates of cognitive impairment to a large sample of WTC-exposed-non-FDNY responders from the General Responder Cohort (GRC; n = 7102) who completed the MoCA during a similar time frame.

Result

Among FDNY responders under 65 years, the unadjusted prevalence of MCI varied from 52.57% to 60.32% depending on the operational definition of MCI, apart from using a conservative cut-off applied to MoCA total scores (18 < MoCA < 23), which yielded a markedly lower crude prevalence (24.31%) compared to alternative criteria. Using propensity score matching, the prevalence of MCI was significantly higher among WTC-exposed FDNY responders, compared to WTC-exposed GRC responders (adjusted RR = 1.13 (CI 95% = 1.07–1.20, p < 0.001), and descriptively higher than meta-analytic estimates from different global, community, and clinical populations. Following NIA-AA diagnostic guidelines, 4.96% of WTC-exposed-FDNY-responders met the criteria for severe impairments (95% CI = 2.91–7.82), a prevalence that remained largely unchanged after excluding responders over the age of 65 years.

Discussion

There is a high prevalence of mild and severe cognitive impairment among WTC-responders, highlighting the putative role of occupational, environmental, and disaster-related exposures in the etiology of accelerated cognitive decline.