Psychometric properties of the BIRT Motivation Questionnaire (BMQ), a self-measure of avolition in individuals with schizophrenia

"Green et al. Paranoid Thoughts Scale-revised": Structural invariance and clinical utility of a brief version in schizophrenia

OBJECTIVE

Persecutory ideas are highly frequent in psychotic disorders and particularly in schizophrenia. Although several measures exist to assess persecutory ideas in both clinical and non-clinical samples, there is a need for brief and psychometrically sound measures to capture the multidimensional aspects of paranoia in people diagnosed with schizophrenia. Our aim was to validate a brief version of the revised Green et al., Paranoid Thoughts Scale (R-GPTS) in schizophrenia in order to minimize time-consuming assessment.

METHODS

100 individuals with schizophrenia and 72 non-clinical controls were recruited. We used the GPTS-8, a brief 8-item version of the R-GPTS recently developed and validated in the French general population. Psychometric properties of the scale were investigated including its factor structure, internal consistency, and convergent/divergent validities.

RESULTS

Confirmatory factor analysis supported the original two-factor structure (social reference and persecution subscales) of the GPTS-8. The GPTS-8 was positively and moderately correlated with the Positive and Negative Syndrome Scale (PANSS) suspiciousness item indicating good internal consistency. Concerning divergent validity, no correlations were found between the GPTS-8 and the Montreal cognitive assessment (MoCA). Importantly patients with schizophrenia reported higher scores on the GTPS-8 than controls demonstrating its clinical validity.

CONCLUSIONS

The French GPTS 8-item brief scale-8 retains the psychometric strengths of the R-GPTS in schizophrenia with relevant clinical validity. The GPTS-8 can consequently be used as a short and quick measure of paranoid ideations in individuals with a diagnosis of schizophrenia.

Preliminary evidence that fatigue contributes to anhedonia in stable individuals diagnosed with schizophrenia

OBJECTIVES

Anhedonia and fatigue are trans-diagnostic symptoms commonly observed in schizophrenia. Anhedonia is a core negative symptom with a strong relationship with depression and is associated with diminished global functioning. Similarly, fatigue is also associated to depression and research across psychiatric illnesses indicate that fatigue may persist even when primary symptoms are treated. Although fatigue is common in people diagnosed with schizophrenia, it is under studied within this population. The objective of this exploratory study was to investigate the association of fatigue and anhedonia by controlling for depression in a sample of individuals diagnosed with schizophrenia.

METHOD

Fifty-one stable individuals diagnosed with schizophrenia from the University Department of Adult Psychiatry in Montpellier took part in this study. Participants completed questionnaires on fatigue impact and depression, and were assessed for symptom severity. Following data collection, statistical analyses were conducted in order to explore associations between clinical variables and fatigue impact. Based on the results obtained, a hierarchical linear regression was conducted in order to investigate whether fatigue impact contributed to the variance of negative symptoms.

RESULTS

The hierarchical linear regression indicated that when controlling for depression, fatigue impact contributes to ~20% of the variance of anhedonia. Together the social impact of fatigue and depression contribute to 24% of the variation of anhedonia.

CONCLUSION

To the best of our knowledge, this exploratory study is the first to investigate and show that fatigue impact may contribute to anhedonia. We recommend further research to investigate fatigue, its impact on symptomatology, and better categorization of negative symptoms in hopes of developing targeted fatigue treatment interventions.