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Symptom network of persistent, remittent MDD related to longitudinal depression

Symptom networks of individuals with major depressive disorder are related to longitudinal depression, with a more densely connected network among persistent than remittent disease, according to recent findings.

“Current classifications do not adequately address this complexity. In novel network approaches to psychopathology, psychiatric disorders are conceptualized as complex dynamic systems of mutually interacting symptoms,” Claudia van Borkulo, MSc, of University Medical Center Groningen, the Netherlands, and colleagues wrote. “This perspective implies that a more densely connected network of symptoms is indicative of a poorer prognosis, but, to date, no previous study has examined whether network structure is indeed associated with the longitudinal course of [major depressive disorder (MDD)].”

Researchers prospectively evaluated 515 individuals from the Netherlands Study of Depression and Anxiety with past-year MDD and at least moderate depressive symptoms, as assessed with the Inventory of Depressive Symptomatology (IDS), at baseline. In this study, remittent and persistent MDD were defined on the basis of a follow-up assessment after 2 years. Baseline was from September 2004 through February 2007 and follow-up was from September 2006 through February 2009. MDD was persistent if individuals had at least moderate depressive symptoms at 2-year follow-up, otherwise, MDD was considered remitted. Study participants had a mean age of 40.9 years.

Overall, 253 participants had persistent MDD at 2-year follow-up.

Individuals with persistent MDD had higher baseline IDS sum score than those with remitted MDD (40.2 vs. 35.1; P < .001).

The network of individuals with persistent MDD was more strongly connected than that of individuals with remittent MDD. Differences in connectivity were still present when controlling for differences in baseline severity by matching on IDS sum score and “partialing out general functioning,” as indicated by the WHO Disability Assessment Schedule II (WHODAS II).

The Network Comparison Test indicated that connectivity differences were statistically significant for all analyses.

The test statistic for difference in network connectivity was 1.79 (P = .01) for original data, 1.55 (P = .04) for data matched on IDS sum score, and 1.65 (P = .02) for WHODAS II data.

Fatigue or loss of energy and feeling guilty had the greatest difference in importance of persistent MDD network compared with remittent MDD network, according to researchers.

“This study found that, when investigating MDD at the symptom level, association patterns are predictive of recovery: a more densely connected network seems related to less positive prospects for recovery from depression,” van Borkulo and colleagues wrote. “This proof-of-principle concept seems to be a promising line of research and offers support for an added value of a different operationalization of psychopathology in terms of symptom network structure.” – by Amanda Oldt

Disclosure: The researchers report no relevant financial disclosures.