The relationship between neutrophil-lymphocyte, platelet-lymphocyte ratio and cognitive functions in bipolar disorder.

OBJECTIVE: Inflammation is an important factor in pathophysiology of bipolar disorder. Neutrophil-lymphocyte ratio (NLR) and platelet-lymphocyte ratio (PLR) analysis are used to predict peripheral inflammation. The aim of this study is to calculate neutrophil-lymphocyte and platelet-lymphocyte ratios, which are inflammatory markers, and investigate their effect on cognitive functions in euthymic patients with objective bipolar disorder. METHOD: Twenty - eight patients with type-I bipolar disorder and 22 healthy controls matched for age, gender and educational status were included in the study. Neuropsychological tests were applied to all participants. Neutrophils, lymphocytes and platelets counts of the participants were measured and NLR and PLR were calculated. RESULTS: There was a significant negative correlation between NLR and Stroop interference score in study group. There was no statistically significant difference in NLR and PLR between study and control group. No significant correlation was found between PLR and neurocognitive test scores. CONCLUSION: This study revealed negative correlation between NLR and Stroop interference scores. We need further prospective studies with larger sample size to investigate role of inflammation on cognitive functions.

[The Relationship of Interleukin-18 and Interleukin-6 Levels with Cognitive Functions in Bipolar Disorder]. / Bipolar Bozuklukta Interlökin-18 ve Interlökin-6 Sitokin Seviyelerinin Bilissel Islevler ile Iliskisi.

OBJECTIVE: Impairment in immune functions is proposed as a key factor in the cognitive decline in bipolar disorder (BD) however there is scarcity of research on the impact of inflammation on cognitive functions. Our aim is to compare IL-18 and IL-6 levels in BD patients and controls and to study the relationship between IL-18 and IL-6 levels and cognitive impairment METHOD: Thirty-six euthymic BD-I patients and 38 age, sex and educational level matched healthy controls were enrolled in the study. All participants were evaluated with neurocognitive tests. The plasma IL-6 and IL-18 levels of both groups were measured with ELISA kits. RESULTS: There was no statistically significant difference between IL-6 and IL-18 levels of patient and healthy control groups. In the patient group, IL-18 level was positively correlated with completed categories score wheras there was a negative correlation with perseverative response and perseverative errors. Moreover IL-18 level was positively correlated with immediate recall, delayed recall and learning scores while there was a negative correlation with stroop interference scores. No correlation was found between IL-6 level and neuropsychological test scores in the patient group. CONCLUSION: This is the first study that investigates the relation of IL-18 with cognitive functions. Possible detrimental or protective effects of IL-18 in BD is not yet clear, however the positive association of IL-18 level and neuropsychological test scores might indicate a neuroprotective role of IL-18 in the euthymic period of BD which is the closest state to physiological condition.