Alexithymia is a multifaceted, transdiagnostic trait characterized by challenges in emotion processing. Affecting up to 10% in the general population, it represents a risk factor for various mental and physical health conditions. Recent neuroimaging studies have elucidated the neural substrates of alexithymia, providing initial insight into altered functional connectivity within key emotional, attentional, and interoceptive networks, potentially impairing emotion processing and everyday functioning. However, no large-scale study has yet confirmed these network alterations.

Resting-state functional magnetic resonance imaging from 575 individuals (ages 29–60, 334 women) in the population-based SHIP-TREND cohort, using regions of interest covering major functional networks across the whole brain, was paired with the 20-item Toronto Alexithymia Scale (TAS-20) to investigate the signature of alexithymia. The analysis accounted for technical variables, sociodemographic factors, lifestyle, and current depressive symptoms.

Higher TAS-20 scores were associated with altered functional connectivity within the frontoparietal network and between the dorsal attention and salience networks. Specifically, the subscale “difficulties identifying feelings” was associated with functional alterations between and within attentional, salience, and sensorimotor networks, indicating a divergent pattern within the salience network.

These findings underscore the widespread impact of alexithymia on brain networks involved in emotional attention, interoception, and somatosensory processing. Controlling for lifestyle factors, current depressive symptoms, and other health indicators supports the specificity of these patterns. This supports the view of alexithymia as a personality trait that affects large-scale network functioning, potentially hampering emotional regulation and self-awareness processes, contributing to mental and physical health risks.