Elevated inflammation levels in depressed adults with a history of childhood maltreatment

Abstract

Context: The association between depression and inflammation is inconsistent across research samples.

Objective: To test whether a history of childhood maltreatment could identify a subgroup of depressed individuals with elevated inflammation levels, thus helping to explain previous inconsistencies.

Design: Prospective longitudinal cohort study.

Setting: New Zealand.

Participants: A representative birth cohort of 1000 individuals was followed up to age 32 years as part of the Dunedin Multidisciplinary Health and Development Study. Study members were assessed for history of childhood maltreatment and current depression.

Main outcome measures: Inflammation was assessed using a clinically relevant categorical measure of high-sensitivity C-reactive protein (>3 mg/L) and a dimensional inflammation factor indexing the shared variance of continuous measures of high-sensitivity C-reactive protein, fibrinogen, and white blood cells.

Results: Although depression was associated with high levels of high-sensitivity C-reactive protein (relative risk,1.45; 95% confidence interval,1.06-1.99), this association was significantly attenuated and no longer significant when the effect of childhood maltreatment was taken into account. Individuals with current depression and a history of childhood maltreatment were more likely to have high levels of high-sensitivity C-reactive protein compared with control subjects (n = 27; relative risk, 2.07; 95% confidence interval, 1.23-3.47). In contrast, individuals with current depression only had a nonsignificant elevation in risk (n = 109; relative risk, 1.40; 95% confidence interval, 0.97-2.01). Results were generalizable to the inflammation factor. The elevated inflammation levels in individuals who were both depressed and maltreated were not explained by correlated risk factors such as depression recurrence, low socioeconomic status in childhood or adulthood, poor health, or smoking.

Conclusions: A history of childhood maltreatment contributes to the co-occurrence of depression and inflammation. Information about experiences of childhood maltreatment may help to identify depressed individuals with elevated inflammation levels and, thus, at greater risk of cardiovascular disease.

FIGURE 1

Differences in effect size (Cohen’s d) units resulting from a priori defined contrasts between controls and other study groups. Effect sizes are commonly interpreted as small when equal to 0.2, moderate when equal to 0.5, and large when equal to 0.8. The “depressed-only individuals versus controls” contrast showed effect sizes of d=0.12 for the inflammation factor, d=0.07 for (log) hsCRP, d=0.16 for fibrinogen, and d=0.06 for white blood cells (WBC). The “maltreated-only individuals versus controls” contrast showed effect sizes of d=0.29 for the inflammation factor, d=0.28 for (log) hsCRP, d=0.19 for fibrinogen, and d=0.22 for WBC. The “depressed+maltreated individuals versus controls” contrast showed effect sizes of d=0.48 for the inflammation factor, d=0.29 for (log) hsCRP, d=0.45 for fibrinogen, and d=0.40 for WBC.