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Author for correspondence: Anthony C. Ruocco, E-mail: [email protected]
Introduction
The family study research design is a key approach for establishing the validity of clinical phenotypes associated with psychiatric illness (Robins and Guze, 1970). Family studies of borderline personality disorder (BPD) are relatively few in number and have mainly focused on the risk of psychiatric disorders in relatives of probands with an index diagnosis of BPD (see White et al., 2003). Most consistently, relatives of probands with BPD show an elevated risk for depressive disorders and impulse-spectrum disorders, such as substance use disorders and Cluster B personality disorders (Loranger et al., 1982; Pope et al., 1983; Soloff and Millward, 1983; Loranger and Tulis, 1985; Schulz et al., 1989; Riso et al., 2000). The risk for BPD is also significantly higher in the relatives of probands with BPD (Loranger et al., 1982; Baron et al., 1985; Links et al., 1988; Zanarini et al., 1988; Gunderson et al., 2011). Furthermore, dimensions of BPD psychopathology, including affective, cognitive, impulse control, and interpersonal dimensions, appear to aggregate in families affected with the diagnosis (Silverman et al., 1991; Zanarini et al., 2004; Gunderson et al., 2011).
Increasingly, family studies of psychiatric disorders have incorporated intermediate phenotype measures, in part, to increase the statistical power of genetic linkage analyses (Gottesman and Gould, 2003; Meyer-Lindenberg and Weinberger, 2006). Only a small number of family studies of BPD have included intermediate phenotype measures, revealing subtle deficits on tests of higher order neurocognitive abilities in probands with BPD and their first-degree relatives (Gvirts et al., 2012) or within a subset of relatives (Ruocco et al., 2012). However, the participant samples are relatively small, limiting explorations of clinical, personality, and neurodevelopmental factors that may moderate the heterogeneous findings. More broadly, family studies of BPD have been limited by notable methodological weaknesses, including small sample sizes, use of different diagnostic instruments across studies to assess BPD, inconsistent masking across studies of the diagnostic assessments of relatives to the proband's diagnosis, and indirect (i.e. informant-based) assessments of relatives (White et al., 2003).
In the present study, we recruited probands with an index diagnosis of BPD and their first-degree biological relatives to a...