Both chronicity and neuroticism can predict the long-term presence of psychiatric symptoms among patients with a major depressive disorder (MDD), according to research published in the Journal of Affective Disorders.       

Researchers analyzed patients with current MDD who were included in the Netherlands Study of Depression and Anxiety to examine whether chronic MDD and neuroticism level could predict the 9-year trajectory of individual depressive symptoms.

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In total, 558 patients (mean age 42.7±12.1; 64.7% women) were analyzed. At baseline, mean sum Inventory of Depressive Symptomology self-report scores were 34.6±11.1, which indicated moderate depression severity. Neuroticism scores were 3.02±0.57 points and were higher in patients with chronic depression at baseline (t=5.31; <.001). Across the entire sample, 21.5% of patients had both chronic depression and a neuroticism level above the median.

Chronic MDD was independently associated with higher severity of depression over 9 years (standardized difference of severity [SDS]=0.131; t=11.023; P <.001) — a 0.131 standard deviation higher average score for the 28 Inventory of Depressive Symptomology self-report scores. On average, individual symptoms were more highly severe in patients with chronic MDD compared with those with nonchronic MDD, including all mood and cognitive symptoms.

In general, patients with higher levels of neuroticism (>43 score) had lower levels of education and were more likely to be chronically depressed and using antidepressants compared with patients with lower levels of neuroticism. Investigators found that high neuroticism was independently associated with a higher depression severity over 9 years (SDS=0.071; t=10.509; P <.001) — a 0.071 standard deviation higher average score for the 28 Inventory of Depressive Symptomology self-report scores. Neuroticism was strongly linked with mood and cognitive symptoms; patients with high neuroticism scores were likely to experience low self-esteem and high interpersonal sensitivity.

“The present study found that a history of chronic depression and neuroticism at baseline was a predictor for the severity of most individual symptoms during 9 years of follow-up,” the researchers wrote.

Study limitations included the observational nature of the cohort, which may have led to several confounding variables, the relationship between chronic depression and neuroticism, and the use of self-reported symptoms.

“[F]uture research might explore whether psychotherapeutic treatments that focus on low self-esteem or interpersonal sensitivity yield better outcomes for individual patients with high neuroticism and/or chronicity,” the researchers of the study concluded, adding that this examination would find whether “personalized interventions lead to better outcomes compared to standardized treatment protocols that approach MDD as a homogenous syndrome for all patients.” 

Reference
Van Eeden WA, van Hemert AM, Carlier IVE, Penninx BW, Spinhoven P, Giltay EJ. Neuroticism and chronicity as predictors of 9-year course of individual depressive symptoms [published online April 15, 2019]. J Affect Dis. doi: 10.1016/j.jad.2019.04.052