Dyslipidemia and blood-brain barrier integrity in Alzheimer's disease

Abstract

Background. Blood-brain barrier (BBB) dysfunction may have a significant role in the pathogenesis of Alzheimer's disease (AD). Modifiable factors associated with BBB function may have therapeutic implication. This study tested the hypothesis that dyslipidemia is associated with BBB impairment in mild-to-moderate AD. Methods. Thirty-six subjects with AD were followed for 1 year. Fasting CSF and plasma were collected with clinical assessments at baseline and 12 months. BBB impairment was defined as CSF albumin index ≥9. Independent t-tests and linear regression assessed the relationship between plasma lipoproteins and BBB integrity. Results. Dyslipidemia was prevalent in 47% of the population, and in 75% of those with BBB impairment. Subjects with BBB impairment had significantly higher mean plasma triglyceride and lower HDL cholesterol (TG, P = 0.007; HDL, P = 0.043). Plasma triglycerides explained 22% of the variance in BBB integrity and remained significant after controlling for age, gender, ApoE-4 genotype, blood pressure, and statin use. Conclusion. Dyslipidemia is more prevalent in AD subjects with BBB impairment. Plasma triglyceride and HDL cholesterol may have a role in maintaining BBB integrity in mild-to-moderate Alzheimer's disease.

Figure 1

Relationship between plasma lipids and blood-brain barrier in subjects with AD. (a) Mean difference in TG = 137.89 mg/dL, P = 0.007. (b) Mean difference in HDL = 16.17 mg/dL, P = 0.043. Standard error bars around the mean set at +/−1.0. (c) Horizontal reference line separates the plots by subjects with (above) and without (below) BBB impairment. Vertical reference line indicates lipid risk threshold.