The CLPS [12, 13] is a multisite, NIMH-funded longitudinal study of the natural course of personality disorders. Participating sites are at Brown, Columbia (now in collaboration with the University of Arizona), Harvard, Yale, and Texas A&M Universities. The aims of the CLPS have been to determine the stability of personality disorder diagnoses and criteria, personality traits, and functional impairment and to determine predictors of clinical course. The original CLPS sample recruited 668 treatment-seeking or recently treated patients who were diagnosed with one of four DSM-IV personality disorders—schizotypal (STPD), borderline (BPD), avoidant (AVPD), or obsessive-compulsive (OCPD)—or with major depressive disorder (MDD) and no personality disorder. Personality disorders were diagnosed at baseline with the semi-structured Diagnostic Interview for Personality Disorders-IV (DIPD-IV) [18] and confirmed by at least one other personality assessment method. Mood and other nonpersonality disorders were diagnosed with the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I) [19]. This original sample was supplemented with the recruitment of 65 additional minority patients to ensure adequate power to test differences between Caucasian, African-American, and Hispanic patients with the four personality disorders on various outcomes. The original CLPS sample completed 10 years of annual follow-up.

To provide more detailed data on persistence vs. change in personality disorder criteria and diagnoses, the interview used to make intake personality disorder diagnoses, the DIPD-IV, was modified in the CLPS to provide monthly ratings of the presence or absence of individual criteria for each of the four disorders under study. This approach was based on the method used to track the course of Axis I disorders in the study, the Longitudinal Interval Follow-up Evaluation (LIFE) [20], resulting in similar ratings of the course of both personality disorders and Axis I disorders in terms of the timing of assessments and the levels of symptoms or criteria present. The monthly ratings of personality disorder criteria also allow determination of various definitions of improvement or remission, based on the number of criteria present and the length of time present or absent. The LIFE has been the central measure of course used in the most comprehensive longitudinal study to date of mood disorders, the Collaborative Depression Study (CDS) [21]. The similarity of methods allows for a comparison of the stability and course of the four CLPS personality disorders with that of several mood disorders and for documenting interactions in the course of personality disorders and mood disorders over time. Primary questions for the CLPS have been whether personality disorders are more diagnostically stable than mood disorders and, when changes occur, which disorder appears to exert an effect on the other, as evidenced by the relative timing of changes in the expression of each type of disorder.

The MSAD [14] was the first NIMH-funded prospective study of the course and outcome of borderline personality disorder. The MSAD sample consists of 290 patients with BPD, diagnosed by both the DIPD-IV [18] and the Revised Diagnostic Interview for Borderlines [22], who were inpatients at McLean Hospital in the early 1990s, and 72 other hospitalized patients who were diagnosed with other personality disorders (OPDs). This comparison group included approximately 4 % with cluster A personality disorders, 18 % with other non-borderline cluster B personality disorders, 33 % with cluster C personality disorders, and 53 % with personality disorder not otherwise specified (PDNOS). The sample has been followed every 2 years for more than 16 years. Remission has been defined as no longer meeting criteria for the index personality disorder for a period of at least 2 years.

Participants of interest were respondents in Waves 1 and 2 of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) [15, 16]. The target population was the civilian non-institutionalized population 18 years and older residing in households and group quarters (e.g., college quarters, group homes, boarding houses, and non-transient hotels) in the United States. Blacks, Hispanics, and adults ages 18–24 were over-sampled, with data adjusted for over-sampling, household- and person-level nonresponse. Of the 43,093 respondents interviewed at Wave 1, census-defined eligible respondents for Wave 2 reinterviews included those not deceased (N = 1,403); deported and mentally or physically impaired (N = 781); or on active military duty (N = 950). In Wave 2, 34,653 of 39,959 eligible respondents were reinterviewed, for a response rate of 86.7 %. Sample weights further adjusted for Wave 2 nonresponse [16]. Overall, most respondents were female, white, over the age of 40, married or cohabiting, and had at least a college education.

In-person interviews were conducted at both waves by experienced lay interviewers with extensive training and supervision. Interviewers administered the NIAAA Alcohol Use Disorder and Associated Disabilities Interview Schedule-DSM-IV Version (AUDADIS-IV) [23], a fully structured diagnostic interview developed to assess substance use and other mental disorders in large-scale surveys. Computer algorithms produced diagnoses of DSM-IV Axis I disorders and all DSM-IV PDs. Major depressive disorder (MDD) was defined according to DSM-IV inclusion criteria, including all symptom, duration, and clinical significance (i.e., distress or impairment) criteria. Diagnoses additionally required that the disorders be “primary,” i.e., not substance induced or due to a general medical condition.

At Wave 1, criteria for MDD were assessed in two time frames: (1) current, i.e., during the last 12 months, and (2) prior to the last 12 months. At Wave 2, 3 years later, these criteria were again assessed in two time frames covering the time period between Waves 1 and 2. Persistent MDD was defined as meeting full criteria for current MDD at Wave 1 and full criteria for MDD throughout the entire 3-year follow-up. Recurrent MDD was defined as meeting full criteria at Wave 1 and again during the last 12 months at Wave 2, but not during the first 24 months after the Wave 1 interview. The impact of all DSM-IV personality disorders on the 3-year persistence and recurrence of MDD was examined.

The CICS [17] is a longitudinal study of a representative sample of approximately 800 children, who were originally recruited (with their mothers) in upstate New York in 1975, when they were between 1 and 10 years of age. They have been followed now periodically for 30 years. Originally, the study was designed to assess level of need for children’s services in the community. When first followed-up in 1983, the focus of the study shifted to predictors of Axis I disorders in early adolescence, but an interest in the development of personality disorders in this age group also existed. Using various methods, personality disorders have been assessed four times: in 1983, when the children were at mean age 14; between 1985 and 1986, when they were at mean age 16; between 1991 and 1993, at mean age 22; and between 2001 and 2004, at mean age 33. The relationships of Axis I disorders and personality disorders have been studied over the follow-up periods.

It is increasingly recognized that, despite conceptual distinctions, there is overlap in some of the psychopathology embedded in the criteria for mood disorders and personality disorders. One relevant model published over 20 years ago proposed that four psychobiological dimensions may underlie both the Axis I disorders and personality disorders: abnormalities in cognition and perception, affect regulation, impulsivity, and anxiety and inhibition [40]. This approach recognizes enduring vulnerabilities or propensities to manifest particular symptoms or behavior, very similar to the notion of personality traits, underlying Axis I disorders. From the perspective of personality, several models describe affective traits [41]. The Five-Factor Model (FFM) [42], for example, includes the trait domain of neuroticism, which is the enduring propensity to experience negative affects such as anxiety, depression, and irritability. Clark and colleagues have described a model of positive and negative affectivity, defining each as “…a stable, heritable, and highly general trait dimension with a multiplicity of aspects ranging from mood to behavior” [43]. They further describe these temperamental dimensions as vulnerabilities for the development of anxiety and depression [43]. The Alternative Model for personality disorders in DSM-5 Section III includes the trait domain of negative affectivity (NA), defined as “frequent and intense experiences of high levels of a wide range of negative emotions (e.g., anxiety, depression, guilt/shame, worry, anger, etc.), and their behavioral (e.g., self-harm) and interpersonal (e.g., dependency) manifestations” [44]. The trait facet of depressivity within the domain of NA is defined as “feelings of being down, miserable, and/or hopeless; difficulty recovering from such moods; pessimism about the future; pervasive shame and/or guilt; feelings of inferior self worth; thoughts of suicide and suicidal behavior” and is one of the “B” (pathological personality trait) criteria for BPD in the DSM-5 Alternative Model. These trait dimensions have been shown to be stable over a period of 6–7 years in a nonclinical sample recruited as college students, at least with regard to rank order stability, although the mean level of negative affectivity showed a significant decrease [45]. As noted by Widiger [41], fluctuations in intensity of the affects associated with temperamental dimensions “…can at times reach clinically significant levels of maladaptivity and warrant a diagnosis of a mental disorder” [41].