Red-cell omega-3 fatty acids associate with increased hippocampal volume and superior longitudinal cognition in atrial fibrillation

Abstract Background Atrial fibrillation (AF) is associated with cognitive impairment and dementia. Omega-3 Fatty Acids (n-3 FAs) have anti-thrombotic, anti-inflammatory and anti-oxidative properties; however, their neuroprotective effects remain controversial. Here, we report the association of n-3 FAs with both structural (hippocampal volume) and functional (cognition) readouts in a large cohort of AF pts. Purpose a) To determine the association of n-3 FAs and left and right hippocampal volume at baseline in AF pts. b) To assess the predictive value of HV and n-3 FAs for the risk of cognitive impairment after a 7-year follow-up period. Methods This prospective ongoing multicenter Swiss Atrial Fibrillation study (Swiss-AF) included 2,359 pts with documented AF and baseline red-cell n-3 FAs levels, measured by gas chromatography and mass spectrometry. Hippocampal volume (HV) and segmentation based intracranial volume (ICV) were analyzed by FreeSurfer's (v 7.4.0) subregion segmentation module and Sequence Adaptive Multimodal SEGmentation from brain MRI in 1,736 pts. Detailed neurocognitive assessments in pts at baseline and follow up periods were performed. We used mixed-effect linear regression models to determine the association of n-3 FAs and HV. For conversion to cognitive impairment (defined as MoCA score < 26), we performed cox-proportional hazards regression model. Two adjustment models were applied as described in the figures. Results Patients with AF (mean age, 73 years old [±8.5 SD]; 157 women [27%]) with 9569 cognitive evaluations (mean follow-up, 3.6 years [±2.3 SD]) were assessed. At baseline, we observed statistically significant associations between total n-3 FAs levels (EPA + DHA + ALA + DPA) and individual n-3 FAs (EPA, DHA, DPA) with increased HV after adjustment for ICV and other covariates (Fig1A, 1B). After all adjustments, EPA remained associated with both bilateral HV and right HV. Furthermore, we observed a significant association between HV and neurocognitive assessments, as measured both in global (MoCA, CoCo) and specific tests (TMT-A, TMT-B, DSST, SF) (Fig1C). Over time, quartile 4 (Q4, highest n-3) compared to quartile 1 (Q1, lowest), had a 16% lower risk of cognitive impairment (HR, 0.84 [CI 0.75-0.93]; P=0.001) for total n-3 FAs and even 30% lower specifically for EPA (HR, 0.7 [CI 0.63-0.78]; P<0.001). The risk of cognitive impairment was 47% lower (HR, 0.53 [CI 0.45-0.63]; P<0.001) when the highest HV Q4 was compared to lowest HV Q1 (Fig2A). In combination, the highest quartile of bilateral HV and EPA demonstrated an increased probability of being cognitive impairment-free and they had a 72% lower (HR, 0.28 [0.18-0.43]; P<0.001) risk of cognitive impairment (Fig2B). Conclusions 1. Red cell n-3 FAs levels are associated with higher HV in AF pts. 2. Higher baseline levels of n-3 FAs, particularly of EPA, are associated with both an increased HV and a decreased risk of cognitive impairment after 7 years follow up.