According to Gold et al. (2017), one of the underpinning reasons for a person with BPD to suffer from identity issues and a lack of a stable sense of self stem partly from a disrupted episodic memory making it harder for them to mentally revisit the past (Gold et al.  refer to this problem as a ‘disruption the temporal sense of self).
Indeed, because the same brain circuits are involved in projecting oneself into a mentally simulated past event and projecting oneself into a mentally simulated future event, the individual who has difficulty imagining him/herself in a reconstructed past also has difficulties imagining him/herself in the future.
More specifically, Gold et al. suggest that the BPD individual who finds it difficult to mentally time travel has the difficulty due to three main problems:
1 PROBLEM WITH SCENE CONSTRUCTION:
The process of imaginatively generating and maintaining a complex and coherent mental representation of a particular event.

2 PROBLEMS WITH SELF PROJECTION:

The ability to alter one’s (temporal) perspective away from the present 

3 PROBLEMS WITH AUTONOETIC CONSCIOUSNESS:

Autogenetic consciousness refers to the sense of ‘owning’ a personal experience and a sense of what has been termed ‘mineness’ about it. It is associated with difficulties planning, thinking about one’s future experiences and the future in general.

PROBLEMS WITH MENTAL TIME TRAVEL INTO THE FUTURE IMPAIRS SENSE OF SELF AND CONTRIBUTES TO DISINHIBITION

Because the BPD sufferer has an impaired ability to mentally project him/herself into the future and to actually feel what it would be like to be there due to impaired autonoetic consciousness, it is much harder for him/her than it is for the average person to fully pre-experience situations and the consequences of his/her actions and behaviors. This, in turn, leads to an impairment of rational decision-making and rational agency, as well as an increase in disinhibition (even seriously bad future consequences of behavior lose their inhibitory power if the BPD individual can not imagine him/herself experiencing such consequences in the future in any substantial and personally meaningful way).

David Hosier BSc Hons; MSc; PGDE(FAHE).

REFERENCE:

Self and identity in borderline personality disorder: Agency and mental time travelNatalie Gold PhD, Michalis Kyratsous MBBS MRCPsych First published: 24 May 2017Wily Online Library https://doi.org/10.1111/jep.12769