Assessment of Trait and State Aspects of Depression in Schizophrenia

Abstract

Depression and negative symptoms can be difficult to distinguish in schizophrenia. Assessments for negative symptoms usually account for the longitudinal nature of these symptoms, whereas instruments available to measure depression mainly assess current or recent symptoms. This construct difference may confound comparison of depressive and negative symptoms in schizophrenia because both domains may have trait-like aspects. We developed an instrument to measure both longitudinal "trait" as well as recent "state" symptoms of depression and tested this instrument (Maryland Trait and State Depression [MTSD] scale) in a sample of 98 individuals with schizophrenia or schizoaffective disorder and 115 community participants without psychotic illness. Exploratory factor analysis of the MTSD revealed 2 factors accounting for 73.4% of the variance; these 2 factors corresponded with "trait" and "state" depression inventory items. Neither MTSD-state nor MTSD-trait was correlated with negative symptoms as measured with the Brief Negative Symptom Scale (r = .07 and -.06, respectively) in schizophrenia patients. MTSD state and trait scores were significantly correlated with the Brief Psychiatric Rating Scale depression subscale (r = .58 and .53, respectively) as well as the Profile of Mood States depression subscale (r = .57 and .44). Persons with schizophrenia had significantly greater trait depressive symptoms than controls (P = .031). Individuals with schizoaffective disorder had significantly higher trait depression (P = .001), but not state depression (P = .146), compared with schizophrenia patients. Trait depressive symptoms are prominent in schizophrenia and are distinct from negative symptoms.

Evaluation of Myo-Inositol as a Potential Biomarker for Depression in Schizophrenia

“…As reported previously (Chiappelli et al, 2014b), SSD patients had greater levels than controls of both trait (mean ± SD: 1.21 ± 1.08 vs 0.55 ± 0.62, respectively, po0.001), and state (mean ± SD: 1.04 ± 0.99 vs 0.30 ± 0.40, respectively, po0.001) depression as measured with the MTSD (Table 1). There was no significant difference in ACC myo-Inositol levels between the SSD (6.84 ± 0.84) and community comparison (6.94 ± 0.60) samples (t = 0.80, p = 0.43; Figure 2a).…”

“…The principal finding of greater levels of depression associated with lower myo-Inositol was stronger for the trait-like experience of depressive symptoms than state depression, suggesting the utility of myo-Inositol as a marker that tracks a more stable, longitudinal aspect of psychopathology, as opposed to a state-dependent measure. Our prior work with this instrument suggested a similar factor structure in symptoms of depression between schizophrenia patients and a community comparison sample, and also found that the MTSD-measured depressive symptoms were distinct from negative symptoms (Chiappelli et al, 2014b). The results here provide convergent validity that the experience of depression is comparable between schizophrenia and affective disorders, in that the neurobiological marker myo-Inositol tracks both in a similar manner.…”

“…Factor analysis revealed that depression symptoms captured by MTSD in both schizophrenia patients and controls were segregated into two domains: trait and state depression. Trait depression reported by the patients through MTSD was distinct from their negative symptoms (Chiappelli et al, 2014b). The MTSD assesses how frequently symptoms of depression were experienced in the week prior to assessment ('State' subscale) and throughout adult life ('Trait' subscale) (www.mdbrain.org/MTSD_instructions_and_scale.pdf).…”

“…However, these studies did not consider whether brain myo-Inositol was related to depression in schizophrenia patients, as would be suggested by studies in MDD. Although the subjective experience of depression is similar between psychotic and mood disorders (Chiappelli et al, 2014b), there have been few studies to examine if the neurobiological correlates of depression also overlap. Therefore, we aimed to examine myo-Inositol in the context of depression in schizophrenia.…”

Testing trait depression as a potential clinical domain in schizophrenia

“…We used the Maryland Trait and State Depression (MTSD) Scale that was developed to provide a tool to overcome this limitation (Chiappelli et al, 2014). This is a self-rated scale performed in an interview setting, with some items assessing the frequency of depressive symptoms experienced over the course of adult life, and other items asking specifically about depressive symptoms experienced in the past week.…”