Lithium exposure and chronic inflammation with activated macrophages and monocytes associated with atherosclerosis in bipolar disorder

Background: Atherosclerosis accounts for cardiovascular diseases (CVDs). This study aimed to explore the association between carotid intima-media thickness (CIMT), psycho-pharmacotherapy, and inflammatory markers along with other molecules related to atherosclerosis in bipolar disorder (BD). Methods: The euthymic patients with bipolar I disorder (BD-I) aged over 20 years were recruited to measure CIMT through ultrasound and the blood levels of lipid profiles, soluble tumor necrosis factor receptor-1 (sTNF-R1), soluble interleukin-6 receptor (sIL-6R), monocyte chemoattractant protein-1, chitinase 3-like 1, endothelial adhesive proteins, and thrombin-antithrombin complex. Results: Participants were 103 BD-I patients with mean 44.3 years old. The ratio of lithium exposure in relation to illness chronicity and the current daily dosage of lithium therapy exhibited an inverse relationship with CIMT in the entire sample. After controlling for age and BMI, multivariate regression indicated that a higher lithium level was significantly associated with decreased CIMT in the entire sample, high-risk (those with CVDs or endocrine diseases, N = 48), middle-risk (those without CVDs and endocrine diseases, N = 55), and low-risk (those aged <45 years in the middle-risk subgroup, N = 43) subgroups. Furthermore, higher levels of sTNF-R1 in the entire sample and high-risk subgroup and sIL-6R in the middle- and low-risk subgroups were statistically associated with greater CIMT. Limitation: The age range was too wide to control for the effect of age on CIMT and medication. Conclusions: Lithium exposure may be a protective factor for atherosclerosis progression in BD-I. The chronic inflammation in BD-I with activated macrophages and monocytes may link with the atherosclerosis development over time.