High CSF cortisol levels are associated with frontal lobe and hippocampal atrophy across patients on the Alzheimer’s disease spectrum

Abstract

AbstractBackgroundMultiple studies have linked high cerebrospinal fluid (CSF) cortisol levels, a frequently used biomarker of stress, with the Alzheimer’s disease (AD) pathophysiology. However, the relationship between CSF cortisol levels and AD‐related brain atrophy is not fully understood. Thus, this study sought to determine the association between CSF cortisol levels and neuroimaging biomarkers of brain structure indexed by magnetic resonance imaging (MRI) in patients across the AD spectrum.MethodsParticipants with baseline measures of CSF cortisol and structural (high‐resolution T1‐weighted) MRI (n = 300) were selected from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) database. The MRI scans were processed with FreeSurfer (v. 7.1.1), and the statistical analyses were performed using R (v. 4.1.1; R Core Team, 2021). We performed a region‐of‐interest (ROI) analysis using a generalized linear model (GLM), to assess the association between CSF cortisol levels and (1) volume of hippocampus, amygdala, subcortical and cortical segmentation, (2) cortical thickness and (3) surface area of cortical structures (Fig. 1). The ROI analysis was corrected by Bonferroni (p < 0.0005).ResultsCSF cortisol levels did not correlate with left hippocampal volume (p = 0.2; Fig. 2A) and mean global brain thickness (p = 0.002; Fig. 2C). However, we found a negative correlation with the volume of left fimbria (r = ‐0.20, p = 0.0003; Fig. 2B) and right superior frontal thickness (r = ‐0.21, p = 0.0003; Fig. 2D). In the regression model, only right superior frontal thickness showed significant association with CSF cortisol levels after adjusting for age (corrected R2 = 0.11, p < 0.0001). The other regions and parameters analyzed did not present significant correlations with CSF cortisol levels.ConclusionsThis cross‐sectional study found an association between elevated CSF cortisol levels and atrophy of left fimbria and right superior frontal in patients on the AD spectrum. Our findings suggest a particular vulnerability to cortisol in selected regions. To the best of our knowledge, this is the first study to assess the associations between CSF cortisol levels and ROIs from hippocampus and amygdala segmentation. Our results have potential implications for understating AD‐related brain atrophy and developing innovative therapeutic strategies.