Background Recent reports suggest that World Trade Center (WTC) responders are at increased risk for cognitive impairment (CI). The current study utilized neuroimaging to determine whether WTC responders with CI have reduced cortical thickness (CTX). Method WTC responders (N=99) with and without CI, recruited from an epidemiologic study of cognitive aging among WTC responders, participated in a neuroimaging study that included a T1‐MPRAGE protocol. CTX was computed in 34 Desikan‐Killiany atlas regions of interest (ROIs). Regional CTX between CI and non‐CI responders were compared using t‐tests and reported using Cohen’s D, and whole‐brain surface‐based morphometry using threshold‐free cluster analysis. Sensitivity analyses were used to examine possible associations of CTX with symptoms of PTSD and/or severity of WTC exposure. Analyses were adjusted for multiple comparisons using the false discovery rate (FDR = 0.05). Results Participants were aged 55.84 years on average, and 47 had CI as determined by clinical mental status examination using the Montreal Cognitive Assessment (MoCA≤20). When compared to unimpaired responders, responders with CI had reduced mean whole‐brain CTX (P = 0.002). Region‐based analyses identified reduced CTX in 21/34 bilateral ROIs (D = ‐0.60) with the largest effects centered in the precentral gyrus (D = ‐0.74, P = 0.007). Surface‐based morphometry revealed that CTX was reduced across large parts of the frontal, temporal, and occipital lobes, all of which remained significant following adjustment for multiple comparisons. While more regions were identified as reduced in responders with both PTSD and CI (18 versus 9 ROIs in responders with PTSD and CI versus CI alone respectively), sensitivity analyses were not able to distinguish CI with PTSD as compared to CI alone. Conclusions Results from structural imaging revealed that WTC responders with CI had reduced cortical thickness across multiple brain regions including but not limited to those commonly affected by Alzheimer’s disease. This study represents the first neuroimaging study investigating CTX as an indicator of CI in WTC responders at midlife.

Introduction The objective of this study was to investigate associations between dementia in World Trade Center (WTC) responders and in vivo volumetric measures of hippocampal subfield volumes in WTC responders at midlife. Methods A sample of 99 WTC responders was divided into dementia and unimpaired groups. Participants underwent structural T1‐weighted magnetic resonance imaging. Volumetric measures included the overall hippocampus and eight subfields. Regression models examined volumetric measure of interest adjusting for confounders including intracranial volume. Results Dementia was associated with smaller hippocampal volume and with reductions across hippocampal subfields. Smaller hippocampal subfield volumes were associated with longer cumulative time worked at the WTC. Domain‐specific cognitive performance was associated with lower volumetric measures across hippocampal subregions. Conclusions This is the first study to investigate hippocampal subfield volumes in a sample of WTC responders at midlife. Selective hippocampal subfield volume reductions suggested abnormal cognition that were associated with WTC exposure duration.

Approximately 23% of World Trade Center (WTC) responders are experiencing chronic posttraumatic stress disorder (PTSD) associated with their exposures at the WTC following the terrorist attacks of 9/11/2001, which has been demonstrated to be a risk factor for cognitive impairment raising concerns regarding their brain health. Cortical complexity, as measured by analyzing Fractal Dimension (FD) from T1 MRI brain images, has been reported to be reduced in a variety of psychiatric and neurological conditions. In this report, we hypothesized that FD would be also reduced in a case-control sample of 99 WTC responders as a result of WTC-related PTSD. The results of our surface-based morphometry cluster analysis found alterations in vertex clusters of complexity in WTC responders with PTSD, with marked reductions in regions within the frontal, parietal, and temporal cortices, in addition to whole-brain absolute bilateral and unilateral complexity. Furthermore, region of interest analysis identified that the magnitude of changes in regional FD severity was associated with increased PTSD symptoms (reexperiencing, avoidance, hyperarousal, negative affect) severity. This study confirms prior findings on FD and psychiatric disorders and extends our understanding of FD associations with posttraumatic symptom severity. The complex and traumatic experiences that led to WTC-related PTSD were associated with reductions in cortical complexity. Future work is needed to determine whether reduced cortical complexity arose prior to, or concurrently with, onset of PTSD.

Introduction This study examined cortical thickness (CTX) in World Trade Center (WTC) responders with cognitive impairment (CI). Methods WTC responders (N = 99) with/without CI, recruited from an epidemiologic study, completed a T1‐MPRAGE protocol. CTX was automatically computed in 34 regions of interest. Region‐based and surface‐based morphometry examined CTX in CI versus unimpaired responders. CTX was automatically computed in 34 regions of interest. Region‐based measures were also compared to published norms. Results Participants were 55.8 (SD = 0.52) years old; 48 had CI. Compared to unimpaired responders, global mean CTX was reduced in CI and across 21/34 cortical subregions. Surface‐based analyses revealed reduced CTX across frontal, temporal, and parietal lobes when adjusting for multiple comparisons. Both CI and unimpaired WTC groups had reduced CTX in the entorhinal and temporal cortices compared to published normative data. Discussion Results from the first structural magnetic resonance imaging study in WTC responders identified reduced CTX consistent with a neurodegenerative disease of unknown etiology.