To assess the associations of blood biomarkers of carbohydrate, lipid, and apolipoprotein metabolisms with the future risk of amyotrophic lateral sclerosis (ALS).
In the Apolipoprotein-related MOrtality RISk study, we enrolled 636,132 men and women during 1985-1996 in Stockholm, Sweden, with measurements of serum glucose, total cholesterol, triglycerides, apolipoprotein B (apoB), and apolipoprotein A-I (apoA-I). Serum low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) were either directly measured or calculated from total cholesterol, triglycerides, and apoA-I. The cohort was followed until the end of 2011. We used Cox models and mixed-effects models to, first, estimate the associations between these biomarkers and ALS incidence and, second, to assess the changes of these biomarkers during the 20 years before ALS diagnosis.
One-unit increase of LDL-C (hazard ratio [HR] = 1.14; 95% confidence interval [CI] = 1.02-1.27), apoB (HR = 1.68; 95% CI = 1.17-2.42), and apoB/apoA-I ratio (HR = 1.90; 95% CI = 1.29-2.78) was associated with a higher incidence of ALS. High glucose level (=6.11mmol/L) was associated with a lower incidence (HR = 0.62; 95% CI = 0.42-0.93), whereas high LDL-C/HDL-C (=3.50; HR = 1.50; 95% CI = 1.15-1.96) and high apoB/apoA-I (=0.90 for men, =0.8 for women; HR = 1.41; 95% CI = 1.04-1.90) ratios were associated with a higher incidence. During the 10 years before diagnosis, ALS patients had increasing levels of LDL-C, HDL-C, apoB, and apoA-I, whereas gradually decreasing levels of LDL-C/HDL-C and apoB/apoA-I ratios.
Alterations in the carbohydrate, lipid, and apolipoprotein metabolisms are associated with ALS risk and may serve as prodromal symptoms decades before ALS diagnosis. The imbalance between apoB and apoA-I as well as between LDL-C and HDL-C may be an etiological mechanism for ALS and needs to be further studied. Ann Neurol 2017;81:718-728.