Study: Long-Term Depression Linked to Schizophrenia

The presence of persistent or “trait” depression is much higher in schizophrenic patients, and is associated with more severe psychosis, according to a new study from the Maryland Psychiatric Research Center at the University of Maryland.

A team of researchers led by Joshua Chiappelli, MD, a psychiatrist and academic fellow at the school, studied the connection between trait depression and cognitive deficits, functional capacity impairment, and white matter integrity in 126 patients and 151 controls recruited from the Maryland Psychiatric Research Center.
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The participants completed the Maryland Trait and State Depression (MTSD) questionnaire, answering a series of 36 questions regarding the frequency of depression symptoms over the past week (state questions), and over the course of their adult lives (trait questions). The authors assessed cognition using the Digit Symbol Coding task of the Wechsler Adult Intelligence Scale and the Digital Sequencing task from the Brief Assessment of Cognition in Schizophrenia. The researchers determined white matter integrity by the measure of fractional anistropy on a diffusion MRI.

The team found that severity of both trait and state depression in patients with schizophrenia was significantly and positively associated with scores on the Brief Psychiatric Rating Scale. A higher MTSD score, meanwhile, was not associated with severe cognitive deficits, the authors note, pointing out that severe trait depression was actually significantly associated with working memory, processing speed, and functional capacity.

In addition, whole brain FA values were higher in controls than in patients with schizophrenia, and higher trait depression scores were significantly linked to higher FA values in schizophrenia patients.

These findings “add to the body of evidence suggesting that depression is a frequent co-morbidity in schizophrenia, and should be assessed even in patients for whom frank psychotic symptoms are the primary presenting problem,” says Chiappelli.

“Furthermore, the findings suggest that, somewhat paradoxically, patients with schizophrenia who appear to have less severe cognitive impairments may actually be more vulnerable to depression than more cognitively impaired schizophrenia patients.”

—Mark McGraw

Reference

Chiappelli J, Kochunov P, et al. Testing trait depression as a potential clinical domain in schizophrenia. Schizophrenia Research. 2014.