APOLIPOPROTEIN-E POLYMORPHISM AND STROKE IN A POPULATION-SAMPLE AGED 75 YEARS OR MORE

Background and Purpose We investigated apolipoprotein E polymorphism s troke risk in a population sample of 1810 persons aged 75 years or mor e in Stockholm (the Kungsholmen Project). Information on cognition at cohort inception (from 1987 to 1989) and on stroke occurrence (from 19 69 to 1994) is available for the cohort. In the cohort, cognitive impa irment is associated with the epsilon 4 allele, and longer survival in subjects aged greater than or equal to 85 years with good cognition i s associated with the epsilon 2 allele and the absence of epsilon 4. M ethods We compared stroke incidence in the 1077 of 1124 genotyped subj ects who carried epsilon 2/3, epsilon 3/3, or epsilon 3/4 and estimate d the proportion of cognitive impairment attributable to stroke. Resul ts Risk of stroke did not vary with apolipoprotein E polymorphism (P=. 82): 24% of 87 incident stroke patients during follow-up compared with 25% of 827 subjects with normal cognition and no stroke diagnosis at baseline carried the epsilon 3/4 genotype. An estimated 9% of cognitiv e impairment was attributable to stroke. Notably, a reduced epsilon 3/ 4 frequency of 20% was found in subjects who survived a prior stroke a nd were included in the cohort, and risk of hemorrhagic stroke tended to be associated with the presence of the epsilon 3/4 genotype and the absence of epsilon 2/3. Conclusions This population-based study indic ates that apolipoprotein E polymorphism is not a risk factor for ische mic stroke in subjects aged greater than or equal to 75 years (althoug h it might possibly influence survival after stroke occurrence and be a risk factor for infrequent hemorrhagic stroke) and that approximatel y 10% of cognitive impairment in this age group is attributable to str oke.