A factor model of the functional psychoses and the relationship of factorsto clinical variables and brain morphology

Background. Despite more than 100 years of study, there remains no definiti ve diagnostic validation of the functional psychoses. Factor analysis sugge sts the presence of three or more psychopathological syndromes in functiona l psychoses as a whole. The relationship between these factors and cerebral anatomy has been investigated in schizophrenia only. This study aimed to a ddress the relationship of symptom factors to clinically important variable s and cerebral anatomy in a sample of psychotic patients with a spread of d iagnoses. Methods. In a sample of patients with functional psychoses, symptom data wa s obtained on four consecutive admissions using the OPCRIT symptom checklis t. OPCRIT data was used to generate operational diagnoses in accordance wit h pre-set criteria and a principle components analysis was performed on sym ptom data. Factor loadings were compared between each admission to examine factor stability over time. Factor scores at first admission were also corr elated with clinical variables obtained from patients' case notes. From the sample of 204 patients, 64 subjects were recruited and underwent an MRI sc an of the brain. Regional anatomical volumes were compared with diagnosis a nd factor loadings at first admission. Results. A principal components analysis gave a four-factor solution of 'ma nic', 'depressive', 'disorganization' and 'reality distortion' factors at e ach admission. Factors showed a high degree of stability over the four admi ssions studied. The factors were significantly associated with several clin ical variables. Three of the four factors were associated with a specific p attern of cerebral anatomy. Conclusions. This study suggests that factors may correspond to relatively specific disease processes underlying functional psychotic illness, We prop ose that the use of symptom factors may facilitate the investigation of the underlying mechanisms of psychotic illness.