APOLIPOPROTEIN-E (APOE) ALLELE FREQUENCIES IN LATE-ONSET SPORADIC ALZHEIMERS-DISEASE (AD), MIXED DEMENTIA AND VASCULAR DEMENTIA - LACK OF ASSOCIATION OF EPSILON-4 ALLELE WITH AD IN ITALIAN OCTOGENARIAN PATIENTS

The Apolipoprotein E (APOE) epsilon 4 allele has been found to be stro ngly associated with Alzheimer's disease (AD) in most studies conducte d up to now, though not all investigators have established a similar a ssociation with other forms of dementia, like vascular dementia. Our s tudy examined the APOE polymorphism in a sample of 149 dementia patien ts, of which there were 80 with probable sporadic late-onset AD, 16 wi th a mixed form of dementia (MD), and 53 with vascular dementia (VD). An elderly control sample was composed of 126 subjects. The data obtai ned on the whole AD sample did not confirm the association already rep orted with APOE epsilon 4. A difference did emerge when the subjects w ere subdivided on the basis of age at the examination. AD patients age d less than or equal to 80 years significantly differed from the corre spondent elderly controls, while no difference was observed between th e patients aged 81 years or older and controls. This pattern could be due to a previous disadvantageous effect of the epsilon 4 allele on th e subjects bearing it. A substantially similar pattern was observed in the few MD patients, while no differences were found in the two VD su bgroups. The odds ratio (OR) for AD associated with at least one epsil on 4 allele was significant and equal to 3.3 (95% CI = 1.2-9.1) for th e less than or equal to 80 age class, while it was not significant and equal to 1.1 (95% CI = 0.4-2.8) for the >80 age class. Our data indic ate that in AD patients aged less than 81 years, epsilon 4 is clearly associated with AD and that it can be considered a risk factor for AD chiefly before this age.