Background: It has been demonstrated that the mechanism of cognitive memory control in humans is sustained by the hippocampus and prefrontal cortices, which have been found to be structurally and functionally abnormal in borderline personality disorder (BPD). We investigated whether the memory control mechanism is affected in BPD.
Method: Nineteen Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV BPD patients and 19 matched healthy controls (HC) performed a specific think/no-think paradigm exploring the capacity of remembering and suppressing pair of words previously learned. After the think-no think phase, the second member of each word pair has to be remembered either when subjects are presented with the cue word showed at the beginning of the test (Same Probe Test; SPT) or when they are presented with an extra-list categorical word (Independent Probe Test; IPT). We evaluated the effect of suppression and of retrieval activity on later retention of words.
Results: Both on the SPT and on the IPT, HC showed the expected improvement of memory retrieval on to-be-remembered words, unlike BPD patients. On the SPT, HC, but not BPD patients, correctly recalled significantly more words among remembered words (RW) than among suppressed words (SW). Similarly to HC, subjects with BPD without a history of childhood abuse showed a significantly higher percentage of correctly recalled words among RW than among SW.
Conclusions: The mechanism of active retrieval of memories and of improvement through repetition is impaired in BPD, particularly in those who experienced traumatic experiences. This impairment might play an important role, possibly resulting in the emergence of unwanted memories and dissociative symptoms.