The McLean Screening Instrument for Borderline Personality Disorder: What, and why in a clinical cohort?

Borderline Personality Disorder is a severe psychiatric disorder with debilitating consequences. Screening for the disorder is problematic as symptoms overlap with other psychiatric disorders. The McLean Screening Instrument (MSI) assesses endorsement (yes/no) of 10 symptoms, with a cut-off of seven indicating potential caseness. Participants were (N = 68) from an established clinical cohort who completed a structured clinical interview, the MSI, the Childhood Trauma Questionnaire, and the Adolescent and Adult Time Attitudes Scale. A proportion (N = 20) also completed a follow-up interview examining their rationale for endorsing MSI items. Total number of MSI items endorsed was meaningfully related to scores on emotional neglect and negative time attitudes. There was substantive overlap between MSI threshold (≥7 items) and lifetime diagnosis of a mental disorder. The stated rationale for endorsing MSI items, was less indicative of personality trait, and was related more to particular developmental periods, one-off episodes, and life-contexts. Additionally, participants conflated constructs such as emptiness with loneliness, and moodiness with general emotionality. Those meeting MSI threshold recalled more childhood emotional neglect, and were more negative about all time periods. It is apparent that scoring of the MSI is driven by prevailing life circumstances as much as enduring personality traits.