Reduced intra-frontal functional connectivity during a verbal fluency task in depressed individuals with autistic traits: an fNIRS study
TL;DR
It is suggested that autistic traits modulate task-evoked large-scale network organization within a clinically relevant depressive-state cohort and support the utility of fNIRS-based network analysis for characterizing neurobiological heterogeneity associated with depressive symptoms.
Abstract
Background Depressive symptoms accompanied by autistic traits represent an important source of clinical heterogeneity. While aberrant functional connectivity (FC) within prefrontal networks has been implicated as a shared neural feature of both autism spectrum disorder (ASD) and depression, task-evoked FC abnormalities in individuals experiencing both remain poorly understood. This study employed functional near-infrared spectroscopy (fNIRS) to evaluate task-evoked FC during a verbal fluency task (VFT), with a focus on prefrontal network organization. Methods Fifty neurotypical controls and 43 individuals experiencing depressive symptoms were enrolled. The depressive-state cohort was further subdivided into high autistic traits (DP_AQ-high) and low autistic traits (DP_AQ-low) subgroups based on Autism-Spectrum Quotient (AQ) scores. FC among channels in frontal, temporal, and inferior parietal regions was calculated using zero-lag Pearson correlation analysis of oxyhemoglobin (HbO₂) and deoxyhemoglobin (HbR) signals during the VFT. Between-group FC differences were evaluated using ANOVA for the Control versus depressive-state comparison, and medication-adjusted ANCOVA for the DP_AQ-high versus DP_AQ-low comparison, with diazepam-equivalent anxiolytic dosage and imipramine-equivalent antidepressant dosage as covariates. Results Relative to neurotypical controls, the depressive-state group exhibited decreased interhemispheric frontal FC across both chromophores, alongside network-specific FC increases and decreases. Within the depressive-state group, the DP_AQ-high subgroup consistently demonstrated increased interhemispheric frontoparietal FC across both chromophores, accompanied by localized intra-frontal FC reductions, compared with the DP_AQ-low subgroup. Conclusion These findings suggest that autistic traits modulate task-evoked large-scale network organization within a clinically relevant depressive-state cohort and support the utility of fNIRS-based network analysis for characterizing neurobiological heterogeneity associated with depressive symptoms.