Two-step cluster analysis application to a sample of psychiatric inpatients at psychiatric service of diagnosis and care

Introduction Recent findings demonstrated significant overlaps among major psychiatric disorders on multiple neurocognitive domains. However, it is not clear which are the cognitive functions that contribute to this phenomenon. Objectives To find the optimal clustering solution using the two-step cluster analysis on a sample of psychiatric patients. Aims To classify into subgroups a cross-diagnostic sample of psychiatric inpatients on the basis of their neurocognitive profiles. Methods Seventy-one patients with psychotic, bipolar, depressive and personality disorders hospitalised at Psychiatric Diagnosis and Care Service of Bufalini Hospital of Cesena participated in the study. The symptomatology was assessed using Health of the Nation Outcome Scales-Roma and Brief Psychiatric Rating Scale. Cognitive functions were evaluated using Tower of London, Modified Wisconsin Card Sorting Test, Judgment and Verbal Abstract Tasks test, Raven matrices, Attentional Matrices, Stroop Test and Mini Mental State Examination. Two-step cluster analysis was conducted using the standardized scores of each neurocognitive test. Results Two groups were obtained:– group 1, with good cognitive performances;– group 2, with almost all subjects having impaired cognitive performances. Executive functions and attention are the major determinants of the cluster solution. The clusters did not differ on socio-demographic correlates. Different diagnoses were equally distributed amongst the clusters. Conclusions Two-step cluster analysis was useful in identifying subgroups of psychiatric inpatients with different cognitive functioning, overcoming other cluster techniques limitations. According to former literature, these results confirm a continuum of severity in cognitive impairment across different psychiatric disorders.