Clinical implications o f study

The major clinical implication of this study's findings is that theory of mind skills may be a worthwhile focus for intervention which in BPD, especially if subsequent studies indicate that poor theory of mind is related to particular symptoms of the disorder (e.g. interpersonal difficulties) or overall severity. The Bateman and Fonagy (1999) model of psychotherapeutic intervention in BPD already has the improvement of mentalisation skills as an explicit focus for treatment, and this treatment package has been shown to be successful in producing good clinical outcomes in a randomised controlled trial. It may be that other treatment approaches that do not have such an explicit aim of improving mentalisation (e.g. Dialectical Behaviour Therapy: Linehan, 1993), would benefit from such a focus. The results of this study also raise the possibility that a mentalisation deficit in BPD may apply even in neutral contexts which are not specifically related to attachment history, contrary to the proposal of Fonagy et al., (2000). This may mean that it could be useful to target the improvement of mentalisation skills in a wide variety of types of situation, including some which appear to be more neutral for the patient. The lack of consistent evidence for executive dysfunction in this study and others means there is not presently any support for the introduction of interventions which specifically target executive difficulties in BPD. However, if subsequent research is able to reliably identify sub-groups of individuals (e.g. Streeter et al., 1995) for whom

executive dysfunction is an issue, then it may be worth considering adapting some interventions which have been used for head trauma patients with dysexecutive difficulties (e.g. Mateer, 1999).

4 .4.3 Suggestions for future research

There are a number of possibilities for future investigation of executive functioning and theory of mind in BPD which are suggested by the results of this study.

As with any new finding, the theory of mind result obtained in this study with the SCT will require replication in order to establish whether it is a robust phenomenon, ideally with the use of a depressed control group in order to tease apart the relative influences of BPD diagnosis and co-morbid depression upon any theory of mind deficit. The use of other developmentally advanced theory of mind tests in the BPD population would also be useful with regard to replication, and may help to confirm (as argued in section 4.2.1) that the SCT assesses theory of mind at a higher level than the HSST. Suitable tests might include the Eyes task (Baron-Cohen et al., 1997) and the Faux-pas detection test described by Stone et al. (1998).

This study failed to find a relationship between SCT performance and personality pathology within the BPD group, as measured by the IIP-PD. As suggested in section 4.2.3 this may have been because the IIP-PD is a general measure of personality pathology which is not designed to be specific to BPD. Future research in this area may be able to demonstrate a relationship between theory of mind performance and a more specific measure of BPD symptomatology (e.g. DIB: Zanarini et al., 1989), which would give a stronger indication of whether theory of mind ability is related to BPD symptoms.

Another way of investigating the relationship between theory of mind and BPD symptoms would be to measure theory of mind skills before and after psychotherapeutic intervention, which would enable one to determine whether positive therapeutic outcome

was associated with changes in mentalising ability. This design may also shed light on whether higher levels of theory of mind may skills be a predictor of good psychotherapy outcome.

If the theory of mind result of this study were to be replicated, future studies may also wish to further investigate whether a mentalisation deficit in BPD is likely to apply equally across all types of situation, or whether it may be more apparent in certain contexts which are relevant to the individual’s attachment history. One possible way of doing this would be to add extra stories to the SCT which would be more likely to be relevant to the attachment history of BPD participants, in order to see if theory of mind performance on these stories was any different to the neutral stories. (This would probably require a pilot study in the normal population to establish that the “attachment stories” were of the same level of difficulty as the neutral ones.)

With regard to future investigations of executive dysfunction in BPD, a study with larger sample sizes may be able to address the issue of whether some sub-groups of patients with BPD (e.g. those with a history of brain insults: Streeter et al., 1995) may have clearer executive function deficits than have been hitherto found in the disorder. If this were to be the case, and if these deficits were found to relate to BPD symptoms, then this may support the introduction of interventions targeting executive dysfunction in a proportion of BPD patients.

Section 4.3.1 suggested that a modified Predicaments test which included scenarios with emotionally charged themes (e.g. threat or loss), would provide the ideal context in which to investigate the potential effect of emotional arousal upon executive functioning in BPD. It may also be useful to omit the of the solution fluency section of the test, in order to ascertain whether individuals with BPD in this study were being helped by being asked to think of many solutions before giving their best answer (as this is a similar procedure to that seen in some CBT approaches to problem-solving: e.g. Hawton and

Kirk, 1989). This change in administration may make the task a more sensitive assessment of executive ability in an interpersonal context.