Here is the first half of the Medscape article:

Demystifying Borderline Personality: The Cyclothymic-Bipolar II Connection

Introduction

Despite considerable overlap between borderline personality disorder and affective disorders based on methodologically sound studies, as prominent a borderline expert as Gunderson[1] has downplayed such a relationship. Such denial is all the more surprising given the fact that his research team[2] reported that borderline patients at some point in their life met criteria for dysthymia (80%) and/or major depressive disorders (100%). For this reason, it is generally conceded that the nature of affective illness in borderline patients is best described as "atypical." The question of the relationship between borderline and affective disorders then is one of characterizing the nature of "atypicality." The thrust of my argument in this report[3] is that the atypicality of the affective dysregulation of patients given borderline diagnoses can be more precisely delineated in terms of cyclothymic and bipolar II disorders.

Defining the Borderline Terrain

In the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV), borderline refers to a discrete operationally defined construct within the "dramatic cluster" of personality disorders. This definition largely derives from the work of Gunderson and Singer.[4] Among its chief merits is the stimulation of a plethora of data-based investigations of borderline conditions since 1980 as well as the development of the Diagnostic Interview for Borderline (DIB) as its structured measurement. Among the limitations of this operationalized approach is that the concept has been oversimplified, even banalized: it has an unwieldy heterogeneity and overlaps significantly, not only with personality disorders within its own cluster, but also with the schizotypal-paranoid and anxious clusters. Of related concern is the fact that DSM-IV criteria, rather than restricting themselves to defining personality attributes, mix traits, symptoms and behaviors -- particularly of an affective nature (Table 1).

Table 1. Core Characteristics of DSM-IV Borderline Personality Rearranged to Highlight Affective Loading

Unstable intense relationships: splitting, object hunger, abandonment depression
Affective instability: mercurial moods, reactive dysphoria, angry outbursts
Behavioral dyscontrol: impulsivity, substance abuse, binge eating, suicidality
Chronic emptiness: boredom
Unstable sense of self: identity disturbances
Micropsychosis: paranoid sensitivity, dissociation

Of even greater concern is that the operational construct may not coincide with what psychoanalysts mean when they make the clinical diagnosis of borderline personality organization. The latter refers to Kernberg's pioneering contributions[5] in delineating a vulnerable psychic structure, rather than a specific nosologic entity. It refers to a class of personality dysfunctions with common defensive operations, reflecting a vulnerable psychic structure that functions at a "stably unstable" level between the classic neuroses and psychoses. Unlike Gunderson's concept of borderline as a specific personality disorder -- which does not lie on the border of any specific mental disorder -- Kernberg's conceptualization maps a large terrain of psychopathology with affective, neurotic, and paraphiliac disturbances. Kernberg's position appears to be more compatible with psychobiologic formulations of borderline, which place this personality disorder on the borders of such disorders as schizophrenic, manic-depressive, and epileptic psychoses. In this framework,[6] borderline refers to formes frustes of the major endogenous psychoses (ie, subschizophrenic, subaffective, or subictal disorders). This paper updates previous contributions by the present author,[6-10] and integrates them with other emerging trends that emphasize the central role of the cyclothymic constitution in the genesis of borderline, atypical, and bipolar II disorders.

Delineating the Affective Border

Initially, the borderline concept developed as a dilute form of psychosis, and its main usefulness was to exclude such patients from the couch. Working in New York, Stone[11] -- who reported that these patients often came from families with manic-depressive and alcoholic members -- can be credited for having been the first to make a persuasive argument about the need to shift from borderline as a subschizophrenic to a subaffective disorder.

Independently, the present author too arrived at the same conclusion: curiously, our work at the University of Tennessee[6,7] had started off with the hypothesis that many patients with borderline personality had affinity to schizophrenic disorders as defined in the framework of the Danish adoption study of schizophrenia. We studied 100 consecutive outpatients -- in a Memphis mental health center -- meeting the Gunderson and Singer criteria[4] for borderline personality. They were clinically evaluated using a semistructured interview based on a modified version of the Washington University approach to psychiatric diagnosis.[12]

Contradicting our starting hypothesis, only 16% were schizotypal.[6] As for other psychopathology, borderline embraced a broader spectrum than we had anticipated. At index evaluation, 66 met the criteria for recurrent depressive, dysthymic, cyclothymic, or bipolar II disorders; other patients met criteria for sociopathic, panic-agoraphobic, attention-deficit/hyperactivity and epileptic disorders. During prospective observation of up to 3 years, and compared with nonborderline personality subjects, borderline probands had a significantly higher risk for developing major affective disorders than schizophrenia spectrum disorders; furthermore, there were 4 completed suicides. Prominent substance abuse history, stormy biographies, and unstable developmental history marked by repeated object loss were common to all borderline subgroups. From a familial standpoint, borderline probands were closest to the affective, especially the bipolar, comparison group. This familial-genetic bipolar link was reinforced by antidepressant associated switches into irritable-angry hypomanic and mixed states in 20% of our sample during prospective observation. (Of note, "paradoxical" disinhibition on antidepressants in borderline patients has also been observed by others.[13,14])

To summarize, the recurrent nature of affective disorder, coupled with familial bipolarity and spontaneous and pharmacologic excursions into brief periods of elation, places the affective pathology of borderline patients in the soft bipolar realm (that can be broadly defined as bipolar II).

The Nature of "Atypicality"

It is often assumed that micropsychotic and dissociative episodes in patients given borderline diagnoses emanate from psychotic processes. This is a misconception. Grandiose or irritable forms of hypomania occurred in a third of our borderline probands with affective diagnoses.[6] Transient drug-induced psychoses secondary to alcohol, sedative hypnotic, psychedelic or stimulant drug use, or withdrawal were reported in nearly half of all borderline cases. Finally, depersonalization-derealization, as well as brief reactive psychoses, were not uncommon in the borderline probands with concurrent panic-agoraphobic diagnoses. Such data provide a useful beginning framework for understanding the "atypicality" of the affective disorder in borderline patients.

To explain the atypicality of the affective state of borderline patients, Gunderson and Phillips[1] contrasted "empty" depression in this personality with the more classical "guilt" depressions in "classical" affective disorder. Thus, their unstable, hostile, and labile moods -- the unrelenting tension and irritability with superimposed paroxysms of rage -- are relegated by these authors back into the characterologic realm. The thrust of this argument is based on a misconception that only classical affective disorder is a "true" affective disorder. In a forensic population, Coid[15] recently provided a compelling description of the affective storms of borderline patients (restlessness, irritability, explosive anger, tension, psychotic anxiety), which lead to -- and alternate with -- the deceptive "calm" and "emptiness" following self-mutilation. Whatever one ends up calling such patients, one cannot but respect their affectively driven temperamental excesses (lest one becomes victimized by them!). Since 1981, the present author[7] has defended the position that a significant proportion of these patients suffer -- and make their loved ones suffer -- as a result of temperamental dysregulation along dysthymic-irritable-cyclothymic lines. Mood lability and hostile emotional avalanches, which characterize borderline patients, seem to derive from such temperamental dysregulation, which is quintessentially affective in nature.