A comparison of the quality of intrusive memories in post-traumatic stress disorder and depression

As in post-traumatic stress disorder (PTSD), intrusive memories (IMs) also play an important role in depression. Evidence about the comparative quality of IMs in PTSD and depression is limited and inconsistent. A total of 28 adults with PTSD, 29 with depression, and 30 controls identified intrusive and voluntary segments of narrative memories of key events. Self-report and language measures of memory quality were obtained. Depressed and PTSD participants reported higher frequency of IMs and higher IM-related interference than controls. IMs in PTSD participants were distinguished from depressed and control participants by higher self-rated distress, higher self-rated sensory quality, and a higher proportion of sensory words in the narrative. The depressed and control groups did not differ on IM quality. PTSD IM segments had more sensory content than voluntary segments and fewer temporal markers. The IM segments of the depressed and control groups had fewer temporal markers than the voluntary segments. Depression severity predicted fewer sensory words in the IM after considering peri-event dissociation and arousal but did not add to the prediction of other IM qualities. A strong sensory quality is a distinctive feature of IMs in PTSD but not in depression. Basic sensory processes contribute to the intrusiveness of remembering in PTSD but not in depression.