Early onset APOE Ɛ4-positive Alzheimer's disease patients: Are they different?

Abstract

Alzheimer's disease (AD) patients who develop symptoms before the age of 65 are classified as early onset (EOAD). The ɛ4 variant allele of apolipoprotein E (APOE ɛ4) is known to be the major genetic risk factor for Alzheimer's disease (AD). Several studies suggested opposite effects of APOE ɛ4 in EOAD and late onset AD. Our aim was to explore the role of APOE ɛ4 variant in a Tunisian cohort of EOAD. We conducted a descriptive and retrospective cross-sectional study including patients with definite AD according to the recommendations of 2011 of the National Institute on Aging and Alzheimer's Association who had APOE genotyping with PCR–RFLP method, recruited from the department of Neurology of Razi University Hospital in Tunisia. We analyzed clinical and neuropsychological data. We included 140 EOAD patients. One hundred patients (71.4%) were APOE ɛ4 carriers. Sex-ratio was 0,67 with no significant differences between APOE ɛ4 carriers and non carriers. Mean age was 76 years and mean age of onset = 56.9 years [41–64] and were both significantly older in APOE ɛ4 carriers (respectively p = 0,046 and p ";〈10−3). Mean disease course was 6,14 years and was significantly shorter in ɛ4 carriers. There were no differences in dementia or executive dysfunction severity in APOE ɛ4 carriers and non carriers (mean MMSE = 14,2 and 16,8(p = 0,083); mean FAB = 7,4 and 8,6 respectively (p = 0,287)). APOE ɛ4 was common in EOAD associated with older age at onset and shorter disease course in line with previous studies.