Exploratory CT-Based Assessment of Emphysema Burden in Smokers with Bipolar Disorder Receiving Lithium Treatment
Şaban Melih Şimşek1, Meltem Hazel Şimşek2, Ruhsel Cörüt1
1Department of Chest Diseases, Giresun University Faculty of Medicine, Giresun, Turkey.
Purpose:
Experimental studies suggest that lithium may modulate emphysema-related tissue injury through activation of the WNT/β-catenin signaling pathway. However, clinical data examining the relationship between lithium exposure and emphysema burden remain limited. This study aimed to investigate the association between long-term lithium use and CT-derived emphysema burden in smokers with bipolar disorder.
Patients And Methods:
This retrospective observational study included 67 smokers with bipolar disorder who had received lithium treatment for at least 5 years and 71 matched controls with similar demographic and smoking characteristics. Quantitative emphysema measurements were obtained from thoracic computed tomography using low attenuation area percentage (LAA%). Multivariable linear regression analyses were performed adjusting for age, sex, BMI, and smoking exposure.
Results:
Right, left, and total lung LAA% values were lower in the lithium-treated group than in controls (7.53% vs 10.11%, p=0.009; 7.73% vs 10.02%, p=0.019; and 7.64% vs 10.07%, p=0.011, respectively). In multivariable analysis, lithium treatment remained independently associated with lower total LAA% after adjustment for age, sex, body mass index, and smoking exposure (B = -2.636, standardized β = -0.236, 95% CI -4.537 to -0.736; p = 0.007). Weak inverse correlations between serum lithium concentrations and emphysema measurements were observed in unadjusted analyses but were no longer significant after multivariable adjustment.
Conclusion:
Long-term lithium exposure was associated with lower CT-derived emphysema burden in smokers with bipolar disorder. Given the observational design and potential influence of inspiratory effort during CT acquisition, these findings should be considered hypothesis-generating rather than evidence of a protective effect. Prospective longitudinal and mechanistic studies are warranted to clarify the relationship between lithium exposure and smoking-related parenchymal lung injury.
