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External Correlates of the Latent Dimensions of Negative Symptoms
Background: The two-factor structure of negative symptoms reflecting Motivation/Pleasure (MAP) and Emotional Expression (EXP) in schizophrenia has permeated the literature. Recent factor analytic studies however suggest that a more narrow-bandwidth five-factor structure that includes anhedonia, asociality, avolition, alogia, and affective flattening, may better fit negative symptom data. The current presentation summarizes results from a series of studies that extensively compared the two-factor and the five-factor model of negative symptoms vis-a-vis their association with external variables. External validators included measures of cognition, function, attitudes, and affect in multinational samples. In addition, laboratory-based measures of were examined in relation to the alternate negative symptom structures. Method: 146 people (Study 1) and 308 people (Study 2) with schizophrenia or schizoaffective disorder were recruited from Spain and the USA respectively. In the Spanish sample, The Brief Negative Symptoms Scale (BNSS), MATRICS Consensus Cognitive Battery (MCCB) and the Personal and Social Performance Scale (PSP) served as measures of negative symptoms, cognition, and function respectively. In the USA sample, the Schedule for the Assessment of Negative Symptoms (SANS), Repeatable Battery of Neuropsychological Status (RBANS), and the Level of Function Scale (LOF) served similar roles respectively. In a US-based sample, the Positive and Negative Affect Scale and the Defeatist Attitude Scale were administered to a sample of 177 individuals. In separate samples, Digital Phenotyping Technology were also used obtained behavioral and ecological momentary assessment variables from samples based in the USA from Binghamton University, University of Georgia, and Louisiana State University. Factor analytic methods and canonical correlational analyses were used to model the association of negative symptoms with negative symptom dimensions comparing the two-factor model to the more complex five-factor model. Results: While the two factor dimension and the five-factors demonstrated similar patterns of associations with external variables, the five-factor dimensions often captured additional patterns of associations missed by the two-factor MAP/EXP dimensions. This pattern was apparent in the majority of the samples examined including psychometric, behavioral, and lab-based data. Discussion: These findings suggest that the recent trend toward conceptualizing the latent structure of negative symptoms as two distinct dimensions, does not adequately capture the complexity of the construct. Moreover, the five narrower bandwidth dimensions may provide additionally useful information about the association of negative symptoms with external variables missed by the broader bandwidth MAP and EXP dimensions. The validity of the five-factor model of negative symptoms has implications for studies of schizophrenia phenomenology and clinical trials design.