Depression symptoms common in schizophrenia patients
MedWire News: Symptoms of depression are common in patients with stable schizophrenia who have not been previously been diagnosed with the mood condition, results from a Spanish study show.
The researchers also found that depression symptoms are not secondary to other symptoms of schizophrenia or the adverse effects of medication.
Writing in the journal Comprehensive Psychiatry, Susana Majadas (University of Salamanca) and team explain: "The presence of depressive symptoms in patients with schizophrenia has been associated with overall worse outcomes and, a greater medical comorbidity, work impairment, a poorer quality of life, a greater risk of relapse or hospitalization, and an increased risk of suicide."
However, they add that the reported prevalence of depression symptoms in schizophrenia patients varies widely between studies, from 6% to 65%.
To investigate further, the team evaluated the prevalence of depression symptoms using a specific and validated tool - the Calgary Depression Scale for Schizophrenia (CDSS) - in 90 stable outpatients, aged 18-50 years, with schizophrenia (n=73), schizoaffective disorder (n=15), or schizophreniform disorder (n=2). None of the patients had previously been diagnosed with depression.
The participants were also assessed using the Positive and Negative Syndrome Scale (PANSS), the Scale for the Assessment of Negative Symptoms (SANS), the Scale to Assess Unawareness of Mental Disorder (SUMD), the Simpson Angus Scale (SAS) for evaluating drug-related extrapyramidal syndromes, and the Barnes Akathisia Rating Scale (BARS).
The researchers found that 28 (31%) patients tested positive for depression, with a score of at least 5 out of a possible score of 13.
Compared to the nondepressed patients, those with depression had a significantly higher mean total PANSS score (59.5 vs 47.6), PANSS general psychopathology score (30.3 vs 23.5), and PANSS negative symptom score (18.5 vs 14.5). They also higher scores on the SANS (41.7 vs 29.2) and BARS (2.0 vs 0.4) than nondepressed patients.
No significant differences were found between the groups in scores for positive symptoms, insight, or extrapyramidal symptoms other than akathisia.
CDSS scores had a high correlation with depressive scores on PANSS and a moderate correlation with the PANSS general psychopathology score. The correlation between CDSS total score and negative symptoms was moderate using the SANS and low with the PANSS negative symptom score.
There was no correlation between depressive symptoms and positive symptoms, insight, or extrapyramidal symptoms, and the correlation with akathisia was low.
Majadas and team conclude: "Our results suggest that patients with schizophrenia in a stable phase frequently have clinically relevant symptoms of depression… and that these symptoms, with the possible exception of a contribution from negative symptoms, are not secondary to other symptoms of their disorder or to extrapyramidal adverse effects of medications."
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By Mark Cowen