2.2. Methods

Blood was collected at home by a research nurse from 114 nonagenarian subjects, who were asked to fast overnight. Two thousand and seventy one subjects (2071) from the MONICA study group had blood available for ApoE allele testing. For consistency with the MONICA study (the reference population), ApoE phenotyp- ing was chosen instead of genotyping because the former technique was used for the MONICA group. ApoE phenotyping was carried out with the method of Menzel and Utterman (1986) based on isoelectric focusing of deplipidated plasma followed by immunoblotting with ApoE serum.

2.3. Statistics

Allele frequencies were estimated by the gene counting method and results analysed using Chi-square analysis, Yates corrected chi-square ((cid:1)2) and Fishers a exact test. P values 0.05 were considered significant.

3. Results

 The results show a shift in the apoE phenotypes in the 90 year old group compared with younger subjects in the MONICA group (Table 1) with a significant decrease in the E4 allele in nonagenarians (7.5%) compared with the MONICA study group (15.9%). Conversely, there was an increase in the E2 allele in nonagenarians (12.2%) compared with the MONICA group (8.3%), which just achieved significance. There was no difference in the frequency of the E3 allele

4. Discussion

These results are of interest because they suggest that subjects carrying the E4 may be less likely to survive into very old age. Conversely, nonagenarians

Although the results are based on observational evidence, these findings fit with the hypothesis that carriage of the E4 allele may predispose to atherosclerosis and/or Alzheimer’s disease thus reducing the chance of survival to very old age, in this study by about 50%. Some other European groups have reported a similar reduction in E4 allele in cohorts of centenarians (Louhija et al., 1994) and octo/nonagenarians (Kervinen et al., 1994; Eggertsen et al., 1993), though like Northern Ireland, these studies have been conducted in geographical areas with a high baseline incidence of atherosclerosis. Although the prevalence of E4 is high in Afro groups (Zehraoui et al., 1997), there is no evidence of a decline in carriage with ageing in the sparse studies done to date. It is hard to know how this may be interpreted except to suggest that environmental and/or other genetic factors are likely to also be ameliorating influences for the E4 gene pool in different geographical areas and add to the belief that successful ageing is a multifactorial process.

With respect to the E2 allele, this study seems to support an association of E2 with successful ageing which is in agreement with Schacter’s finding but which is more difficult to explain. An analysis of the profile of E2 carriage in nonagenarians in the BELFAST study, suggested that almost all carried only one allele of E2 and most associated with E3 rather than E2 or E4. This is interesting, since carriage of the homozygous E2/E2 phenotype in younger subject groups, is associated with hypertriglyceridemia and predisposition to atherosclerosis (Utermann, 1987). It has been suggested that genes, which may be damaging or detrimental in younger groups may have benefits for the aged subjects in keeping with the ‘thrifty gene’ hypothesis.

The nonagenarian subject group in this study was not selected by age alone but was highly selected for health by closely approximating to the SENIEUR protocol, which has been widely used for immunological studies of ageing. Since healthy ageing is not universal, selection for good health may have had important effects on the analysis by exaggerating ApoE age-related effects. However, a good quality

ApoE alleles E2 E3 E4 MONICA (2071) 8.3% (343) 75.8% (3141) 15.9% (658) Rea (cid:1)90 years (114) 12.2% (14) 80.3% (202) 7.5% (12) X2=4.45 n.s. X2=11.76 P=0.047 P=0.0006 OR=1.55 (1–2.4) OR=0.43 (0.3–0.7)

healthspan is what most of us aspire to and factors which give us the best chance of obtaining it are important to dissect out. At present, it looks as if having one E2 allele might be a useful start, at least for Caucasian subjects. However, it will be important to follow up the nonagenarian cohort, to access information about morbidity and mortality rates and replicate the findings elsewhere.

References Alafuzoff, I., Helisalmi, S., Mannermaa, A., Soininen, H.,

Severity of cardiovascular apolipoprotein E genotype, and brain pathology in ageing and dementia. Ann. NY Acad. Sci.

–

Bladbjerg, E.M., Anderson-Ranberg, K., de Maat, M.P., Kristensen, S.R., Jeune, B., Gram, Jespersen, J.,

Longevity is independent of common variations in genes associated cardiovascular risk. Thromb. Haemost.

,

–

Corder, E.H., Saunders, Al M., Risch, N.J., Strittmatter, W.J., Schmechel, D.E., Gaskell, Rimmler, J.B., Locke, P.A., Conneally, P.M., Schamader, K.E., Small, G.W., Roses, A.D., J.L., Periack-Vance, M.A.,

Protective effect of apoprotein E type

allele for late Alzheimers disease. Nat. Genet.

,

–

Eggertsen, G., Tegelman, R., Ericsson, S., Angelin, B., Berglund, L.,

Apolipoprotein E phism in healthy Swedish population: variation of allele frequency with age and relation to lipid concentrations. Clin. Chem.

,

–

Farrer, L.A., Cupples, A., Haines, J.L., Hyman, B., Kukull, W.A., Mayeux, R., Myers, Pericak-Vance, M.A., Risch, N., van Duijn, C.M.,

Effects of age sex and ethnicity on association between apolipoprotein E genotype and Alzheimers disease. J. Am. Med. Assoc.

–

Folstein, M.F., Folstein, S.F., M

ugh, P.R.,

Mini mental state, a practical method for the cognitive state of patients for the clinican. J. Psychiatr. Res.

,

–

Galinsky, D., Tysoe, C., Brayne, C.E., Easton, D.F., Huppert, F.A., Dening, T.R., Paykel, Rubinsztein, D.C.,

Analysis of the apo E/apo C-I, angiotensisn converting enzyme methylenetetrahytdrofolate reductase genes as candidates affecting human longevity.

,

–

Haan, M.N., Shemanski, J., Jagust, W.J., Manolio, T.A., Kuller, L.,