Alexithymia is a documented syndrome, common among survivors of severe and prolonged trauma: a genuine inability to identify or describe one's own emotional states, not from unwillingness to talk about feelings but from an actual difficulty accessing what those feelings even are. This isn't the same as suppression or denial, where a person knows what they feel but chooses not to express it — alexithymia describes a real gap in the capacity to notice and name internal emotional experience in the first place.
This matters clinically because standard talk therapy, which generally assumes a client can identify and describe their feelings as a starting point, runs into a real obstacle with alexithymic patients — the deficit isn't a communication style to work around, it's a genuine capacity that trauma treatment often has to help rebuild before conventional talk-based approaches can be fully effective.
Psychiatrist Henry Krystal's studies of Holocaust survivors identified alexithymia as a common, durable long-term consequence of severe, prolonged trauma — many survivors, decades after the war, showed a genuine and consistent difficulty identifying or describing their own internal emotional states, not out of reluctance to discuss their experiences but from an actual gap in the capacity to notice what they were feeling in the first place. Van der Kolk builds on this research, describing later neuroimaging work (by researcher Paul Frewen) that found distinct brain activation differences between traumatized subjects with and without alexithymia, providing physiological evidence for the syndrome rather than just behavioral observation.