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Five-factor model best conceptualizes latent structure of negative schizophrenia symptoms

Data from three cross-sectional studies revealed that the latent structure of negative symptoms in schizophrenia was best conceptualized using a five-factor model with separate factors for the five consensus domains issued by NIMH — blunted affect, alogia, anhedonia, avolition and asociality.

These findings indicate that the trend toward conceptualizing the latent structure of negative symptoms as two distinct dimensions fails to capture the construct’s full complexity.

“[Exploratory factor analysis] studies supporting the two factors have been influential, informing how researchers search for pathophysiological mechanisms of negative symptoms and how pharmaceutical companies have recently been approaching targeted treatment development,” Gregory P. Strauss, PhD, department of psychology, University of Georgia, and colleagues wrote in JAMA Psychiatry. “However, these decisions may not be empirically supported, and a more fine-grained approach may be warranted.”

Previous research has surmised latent structure via exploratory factor analysis, concluding that two dimensions reflect motivation and pleasure (MAP) and diminished expressivity (EXP) factors; however, it’s unknown whether these findings are statistically correct because exploratory factor analysis does not test latent structure.

Therefore, researchers used confirmatory factor analysis to examine and compare the fit of four models of the latent structure of negative symptoms in schizophrenia in three cross-sectional studies conducted on 860 outpatients with schizophrenia. Confirmatory factor analysis assessed:

• a one-factor model;
• a two-factor model with EXP and MAP factors;
• a five-factor model with separate factors for the five NIMH consensus domains (blunted affect, alogia, anhedonia, avolition and asociality); and
• a hierarchical model with two second-order factors reflecting EXP and MAP and five first-order factors reflecting the five consensus domains.

The investigators reported patient outcomes, which included confirmatory factor analysis model fit statistics derived from symptom severity scores rated on the most current measures: Scale for the Assessment of Negative Symptoms (SANS), Brief Negative Symptom Scale (BNSS) and Clinical Assessment Interview for Negative Symptoms (CAINS).

Strauss and colleagues conducted confirmatory factor analysis on each scale, including 268 patients for the SANS, 192 for the BNSS and 400 for the CAINS. The one- and two-factor models provided poor fit for the all scales, but the five-factor and hierarchical models provided excellent fit. For the latter two factor models, comparative fit indexes and Tucker Lewis indexes met the 0.95 threshold and the 1.00 threshold with all three measures. Indicators of relative fit favored the five-factor model over the hierarchical model in the BNSS and CAINS data, while the hierarchical model were slightly superior in the SANS data.

“The latent structure of negative symptoms is best conceptualized in relation to the five domains identified in the 2005 NIMH consensus development conference,” Strauss and colleagues wrote. “If distinct clinical and pathophysiological correlates of these five domains are identified in future research, this approach will warrant a change in how negative symptoms are conceptualized and how targeted treatment development is approached.” – by Savannah Demko

Disclosure: Strauss reports developing the Brief Negative Symptom Scale, and receiving royalties and consultation fees from ProPhase, LLC, which are donated to the Brain and Behavior Research Foundation. Please see the study for all other authors’ relevant financial disclosures.