|1.4.2 Schizophrenia and Borderline Personality Disorder|
Two more disorders that are important to differentiate from but in some respects appear related to Bipolar disorder are Schizophrenia and Borderline Personality disorders.
The separation of manic depressive illness from schizophrenia was an important diagnostic task undertaken early on by Kraepelin (1896, 1919) who saw schizophrenia (“dementia praecox”) as a psychotic illness and a thought disorder, characterised by a steady downhill in cognition leading to chronic dementia, whereas manic depressive illness was seen as an episodic affective disorder with intermittent recovery. Although there is great heterogeneity in the symptom profiles of schizophrenia (or different schizophrenias), some of the primary symptoms of it such as delusions, hallucinations, disorganised behaviour (positive symptoms) and lack of insight can often appear in manic episodes to the extent that the two disorders may initially appear indistinguishable.
This is especially true if a cross-sectional approach is taken on the diagnosis without considering the history, content, and course of the symptoms even during the syndromal phases of each disorder. During manic episodes a key diagnostic feature is the mood congruence (or incongruence) of delusions as well as their content. Schizophrenic patients are more likely to have affect free or incongruent bizarre delusions, worse pre-morbid functioning prior to illness onset, and less insight throughout their illness. A factor analytic study of thought disorder (Solovay et al., 1987) that compared schizophrenic and manic patients found that combinatory and over-inclusive thinking was highly elevated in manic patients, whereas schizophrenics were more likely to have high levels of idiosyncratic, absurd, autistic, fluid and confused thinking.
Finally and perhaps most importantly during attempts to diagnose each disorder in remitted phases, the level of insight in bipolar patients appears to diminish only during manic phases of the illness (Ghaemi and Rosenquist, 2004), whereas in schizophrenia lack of insight is more chronic and trait-like. Also in bipolar disorder during subsyndromal phases the report of symptoms may be undermined mainly by social desirability biases rather than lack of insight as it would be in schizophrenia. Social desirability has been found to be high in bipolar patients (Neale, 1988) but no such reports exist in schizophrenia.
But most importantly the greatest challenge for diagnosing correctly bipolar disorder is brought up by Borderline personality disorder.
In many respects patients with Borderline personality disorder present a symptomatic picture that is not that different from bipolar disorder. They present both with depression and hypomanic symptoms and with extreme mood variability. Given that all personality disorders are also defined by the chronicity of particular problematic behaviours (easily misinterpreted as sub-syndromal symptoms), which are not usually severe enough to require acute treatment. In DSM-IV “Borderline personality disorder” is defined as “a pattern of instability in interpersonal relationships, self-image, and affects, and marked impulsivity”. However, many researchers have argued that borderline PD is a part of the bipolar spectrum and is closer to the bipolar II sub-type (Akiskal, 2004). Frank (2005, see p. 54) provides a thorough discussion on the similarities and differences between the two disorders. Symptoms that appear to be unique to borderline disorder are affective instability due to marked reactivity in mood, identity disturbance, chronic feelings of emptiness, dissociative states, frantic efforts to avoid real or imagined abandonment, recurrent suicidal threats, and self-mutilating behaviour. Even from this list of apparently unique borderline symptoms, “affective instability due to marked reactivity in mood”, and the fact that Borderline patients do not have full blown manic episodes (even if one decides to view this category as part of the bipolar spectrum), by diagnostic definition alone this group is not going to have either a history or a future of manic episodes.
Kraepelin, E. 1913. Psychiatrie. Ein Lehrbuch fu ̈r Studierende und A ̈rzte, Leipzig Germany: Barth.