Neutrophil-lymphocyte ratio is increased in elderly patients with first episode depression, but not in recurrent depression

Association between inflammation and depression, especially in elderly patients, leads to conclusions about their shared influence on risk of cardiovascular disease and death. It might be found useful to predict those issues by monitoring inflammatory parameters, such as neutrophil/lymphocyte ratio (NLR). The aim of this study was to determine the NLR in elderly patients with unipolar depression compared with non-depressed elderly patients. NLR was measured in 684 Caucasian subjects (depressed: n = 465, non-depressed: n = 219), aged ≥ 60 (depressed: mean age 74.8 ± 7.8 years, non-depressed: mean age: 71.1 ± 5.7 years). There were two subgroups within depressed patients: first episode depression (n = 138, 29.6%) and recurrent depression (n = 328, 70.3%). NLR was calculated as ratio between absolute neutrophil count to absolute lymphocyte count. NLR was significantly higher in unmedicated patients with depression compared with healthy control (2.10 ± 2.13 vs. 2.01 ± 0.75, p = 0.004). It was higher in first episode depression compared with recurrent depression (2.11 ± 1.76 vs 1.64 ± 1.04, p < 0.05). There was a positive correlation with severity of symptoms. We found non-specific effect of treatment with antidepressants or antipsychotics on lower NLR. Increased NLR in patients with first episode of depression compared to recurrent depression and healthy control may have important clinical consequences. Severity of symptoms are positively correlated with NLR, which may indicate that with increasing severity of depression, the risk of cardiovascular events is also rising, which leads to higher mortality. In elderly patients with depression even a small reduction of such risk may translate into better prognosis and improve quality of live. The difference between first episode and recurrent depression in terms of inflammatory biomarkers requires further studies.