Poster Session II - A227 BRAIN NEAR INFRARED SPECTROSCOPY REVEALS A POTENTIAL LINK BETWEEN PREFRONTAL CORTEX HYPOXIA, MITOCHONDRIAL DYSFUNCTION, AND ALTERED INTEROCEPTION IN CROHN’S DISEASE

Abstract Background Crohn’s disease (CD) patients show heightened interoceptive awareness (perception of internal body sensations), which may worsen psychological distress. The prefrontal cortex (PFC) plays a key role in processing interoceptive signals. PFC hypoxia can be measured as low tissue oxygen saturation (StO2) by frequency-domain near-infrared spectroscopy (FD-NIRS). Mitochondria are key cellular oxygen consumers, and hypoxia can alter their function/structure. NIRS light scattering (NIRS-LS) can detect mitochondrial dysfunction in vivo. Thus, we hypothesized that low PFC oxygenation could lead to mitochondrial dysfunction and altered interoception in CD. Aims To investigate whether PFC NIRS-LS is altered in CD patients compared to healthy controls (HCs) and examine its relationship to PFC hypoxia and interoceptive awareness. Methods HCs (n=15, age 44±15) and CD patients (n=26, age 49±14) were recruited. CD patients were grouped as remitted (rCD; n=16, age 51±14) and active disease (aCD; n=10, age 46±15) using the Harvey-Bradshaw Index. Resting PFC FD-NIRS was measured to obtain StO2 and NIRS-LS (measured as µs at 690nm and 824nm; wavelengths sensitive to the absorption spectra of oxyhemoglobin and deoxyhemoglobin). Interoceptive awareness was assessed in the CD cohort using the Multidimensional Assessment of Interoceptive Awareness (MAIA) questionnaire. µs was compared between HC, rCD and aCD (ANCOVA, age-controlled) and correlated with PFC StO2 (partial Pearson, HC & CD) and MAIA scores (partial Spearman, CD), controlling for disease activity (aCD vs rCD). Results µs at 690nm or 824nm did not differ significantly between HC, rCD and aCD (Table 1). In the overall CD cohort, there was a moderate positive correlation between StO2 and µs at both wavelengths (r=0.4, p=0.03 for both). This relationship was not seen in HC. In CD, µs at 690nm and 824nm correlated moderately/strongly and negatively with MAIA subscales: noticing (r=-0.6 and -0.5, respectively, p=0.01 for both), attention regulation (r=-0.7, p<0.001 for both), and trusting (r=-0.7, p<0.001 for both) (Fig. 1). Conclusions Reduced PFC NIRS-LS correlated with lower PFC oxygenation and higher MAIA scores in CD patients. Lower µs occurs in ischemic brain injury and is reported to reflect mitochondrial dysfunction. Our findings suggest a potential link between PFC hypoxia, mitochondrial dysfunction, and enhanced interoception in CD. Funding Agencies CIHR