Subclinical thought disorder: Development and validation of a clinician -report measure

Subtle manifestations of thought disturbance, or subclinical thought disorder (STD), appear in several psychiatric diagnoses, such as personality disorders and residual psychotic disorders. The present study investigated the nature of STD with the aim of addressing two questions. First, is STD a unidimensional or multidimensional construct? Second, what etiological variables are associated with STD? Identifying different dimensions of STD could contribute to the refinement of the diagnostic criteria for schizotypal personality disorder (SPD) and address a longstanding conundrum in the literature about the comorbidity between SPD and borderline personality disorder (BPD), by distinguishing forms of STD uniquely associated with each. We developed a 90-item clinician-report measure of STD: the Subclinical Thought Disorder Inventory (STDI). The present study outlines the development and validation of the measure. Psychologists and psychiatrists (N = 307) randomly chosen from the membership registers of the American Psychological and American Psychiatric Associations provided demographic, diagnostic, developmental history, and family psychiatric history data on a nonpsychotic patient from their current practice. Factor analysis of the measure produced an eight-factor solution: (1) affective disruption; (2) concrete/impoverished thinking; (3) alternative beliefs/superstitiousness; (4) cognitive/linguistic slippage; (5) memory impairment; (6) peculiar/paranoid cognition; (7) dissociation/perceptual aberration; and (8) psychotic symptoms.;Analyses examined the relationship of these factors to diagnostic, developmental, and family psychiatric history data. The affective disruption and dissociation/perceptual aberration factors showed expected relationships with variables typically associated with BPD (e.g., suicide attempts, unstable relationships, poor relationships with parents), whereas the concrete/impoverished thinking, cognitive/linguistic slippage, and peculiar/paranoid cognition factors correlated in theoretically meaningful ways with criterion variables related to SPD (e.g., lack of confidantes, biological family history of psychosis). Developmental history variables showed a strong relationship to STD in females but not in males. A family history of psychosis was associated with STD in both sexes but was more sensitive and specific in males. Different types of STD are associated with specific adult and childhood adaptive functioning variables, Axis II diagnoses, and developmental and family psychiatric history variables, in ways that suggest distinct pathways to the development of STD.