The APOE Genotype in Idiopathic Normal Pressure Hydrocephalus

Introduction Amyloid plaque has been reported in brain biopsies from patients with idiopathic normal-pressure hydrocephalus (iNPH) and proposed as a significant feature of the pathophysiology. Presence of the apolipoprotein E epsilon 4 (APOE epsilon 4) allele is associated with increased risk of Alzheimer's disease (AD). Aims To compare the distribution of APOE genotype in iNPH patients with an age-matched population- based control group and with Alzheimer's disease (AD) patients. Methods APOE genotype frequencies were determined in 77 iNPH patients (50 men and 27 women, mean age 71.7 years) diagnosed with iNPH, a sample of 691 AD patients and 638 agematched population controls (299 men and 339 women) from the INTERGENE cohort. Results The APOE distribution did not differ significantly between the iNPH patients and the control population. The per e4-allele odds-ratio (OR) of iNPH was given by OR = 0.90, 95% confidence interval (CI) = (0.50, 1.60) that was considerably smaller than the per-allele OR of AD, OR = 5.34 (4.10, 7.00). Conclusion The results suggest that the APOE-related risk of AD in patients with iNPH is not higher than in the general population.