Catatonia Spectrum: Validation of a Questionnaire Investigating Catatonia Spectrum

AIM: A growing body of literature has demonstrated the utility of a dimensional perspective on mental disorders. The current study aims to determine the psychometric properties of the Catatonia Spectrum (CS), a new questionnaire specifically tailored to assess the spectrum of catatonia, from full blown forms to subthreshold ones. METHODS: 86 adults with at least three symptom criteria for catatonia according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), 81 adults affected by borderline personality disorder (BPD), 104 adults with a diagnosis of major depressive disorder (MDD), and 105 subjects without mental disorders (CTL), were recruited from six Italian University Departments of Psychiatry and administered the: Bush-Francis Catatonia Rating Scale (BFCRS), Bush-Francis Catatonia Screening Instrument (BFCSI), and CS. RESULTS: CS scale demonstrated a high level of internal consistency and excellent test-retest reliability for total and domain scores. CS domain scores were positively and significantly correlated with each other (p < 0.001) with Pearson’s coefficients ranging from 0.337 to 0.663. All the CS domain scores were highly correlated with the CS total score. The correlation coefficients between CS and alternative measures of catatonia appeared all significant and positive. Significant differences among diagnostic groups on both CS domains and total scores were found. CS total scores increased significantly and progressively from the CTL, to the MDD and the BDP group, up to the catatonia group, which reported the highest value. CONCLUSION: The CS showed excellent internal consistency and test-retest reliability and strong convergent validity with alternative dimensional measures of catatonia. The questionnaire performed differently across the four diagnostic groups, with an increasing score gradient from healthy controls to patients with MDD, BPD and up to the catatonia group.