Introduction: There is a strong association between the e4 allele of apolipoprotein E (APOE) and Alzheimer's disease (AD). This converts this allele into a risk factor for the development of AD. The association between APOE4 and dementia with Lewy bodies (DLB) is under discussion. In DLB, the presence of APOE4 has been related with a greater amount of senile plaques and neurofibrillary tangles.
Method: This is a case-control study in which the APOE genotype was determined using the modified PCR technique of Wenham in 306 patients with diagnosis of probably AD, NINCDS-ADRDA criteria, 58 cases of probably DLB, McKeith et al. consensus criteria (1996), all of them with SPECT with pathological 123I-FP-CIT and 80 normal controls (NC) having similar age and gender distribution.
Results: The frequency of alleles was: DLB group epsilon4: 16%; epsilon3: 75%; epsilon2: 9%; AD: epsilon4: 32%; epsilon3: 67%; epsilon2: 1%; and in the normal control group: epsilon4: 12%; epsilon3: 83%; epsilon2: 5%. The percentage of alleles in both genders was similar in the three groups.
Conclusions: APOE4 percentage in DLB group (16%) was lower than in AD group (32%), and similar to the control group (12%). Considering that the presence of morphopathological Alzheimer type alterations in DBL, essentially neurofibrillary tangles, is inversely correlated with the presence of Parkinsonian signs, this group may represent pure forms of the disease, although the lack of neuropathological demonstration does not make it possible to confirm this hypothesis.