APOE-ε4 polymorphism and cognitive deficit among the elderly population of Fernando de Noronha

Abstract

-Background: Polymorphism of the gene for apolipoprotein E (APOE) is an important risk factor for the development of Alzheimer's disease. The ε4 allele of the APOE gene has been linked with a number of neuropsychiatric illnesses, and also with stress and depression among geriatric populations. Objective: To identify APOE-ε4 polymorphism and correlate this with cognitive deficit among the elderly population of the island of Fernando de Noronha. Method: Neuropsychiatric tests (mini-mental state examination, verbal fluency test and clock drawing test) were applied to 52 elderly people without Alzheimer's disease. DNA was isolated from peripheral blood and genotyping of APOE was done by the PCR-RFLP method. Results: 87% of the elderly population (mean age 69.6±7.0) had cognitive deficit. Conclusion: The observed frequency of the ε4 allele was 10%, but the correlation between the presence of ε4 and cognitive deficit in this population was not statistically significant.KEY WORDS: APOE, polymorphism, elderly people, cognitive deficit. Polimorfismo de APOE-ε4 e déficit cognitivo na população idosa de fernando de noronhaResumo -Introdução: Polimorfismos no gene da apoliproteína E (APOE) são importantes fatores de risco para o desenvolvimento da doença de Alzheimer (DA). O alelo ε4 do gene APOE tem sido relacionado com declínio cognitivo e algumas doenças neuropsiquiátricas, primariamente a doença de Alzheimer. Objetivo: Identificar os polimorfismos de APOE-ε4 e relacionar com deficit cognitivo na população idosa da ilha de Fernando de Noronha. Método: Foram aplicados testes neuropsiquiátricos (mini exame do estado mental, teste de fluência verbal e teste do relógio) em 52 idosos sem DA. O DNA foi isolado do sangue periférico e a genotipagem de APOE foi realizada por PCR-RFLP. Resultados: 87% da população idosa com idade média de 69.6±7.0 apresentou déficit cognitivo. Foi observada uma freqüência de 10% do alelo ε4. Conclusão: Não foi encontrada significância estatística quando relacionada a presença deste alelo e déficit cognitivo nos idosos avaliados.

Association between alzheimer’s disease and apoe gene genotypic polymorphisms: systematic review and meta-analysis / Associação entre doença de alzheimer e polimorfismos genotipicos do gene apoe: revisão sistemática e metanálise

“…Concurrent to these and to our study, Garcia et al 54 Regarding the genotypic frequencies of the APOE gene, Zhou et al 40 and Demarchi et al 56 presented results very similar to those found in this meta-analysis. When evaluated together, they demonstrated that the Ԑ4 allele plays a role as a risk factor, while the Ԑ2 allele has a protective factor weight, agreeing with our results on its association with the genetic protection condition.…”

Gene polymorphisms of CETP and apolipoprotein E in elderly subjects with cognitive impairment

“…Moreover, we observed an interesting association of the APOE ε2 allele distribution with the CETP B2 allele in elderly subjects: healthy elderly subjects had an increased frequency of the APOE ε2/ CETP B2 combined genotype (18.3%) as compared to the mentally affected elderly subjects (7.6%, P=0.011) ( Table 4). There was no statistically significant with other reports showing that the APOE ε4 allele is not associated with cognitive deficit [19][20][21]. Other investigators, however, reported that the presence of at least one ε4 allele was associated with faster cognitive decline in Alzheimer's disease patients [22].…”

APOE ε4 and cognitive function in early life: A meta-analysis.

“…In addition, more than a decade of research has also demonstrated deficits in various cognitive domains in nondemented ε4 carriers in comparison with non-ε4 carriers in middle and old adulthood (e.g., Berr et al, 1996; Cantu, 2000; De Blasi et al, 2009; Driscoll, McDaniel, & Guynn, 2005; Greenwood, Lambert, Sunderland, & Parasuraman, 2005; Helkala et al, 1995; Lavretsky et al, 2003; Negash et al, 2007; Packard et al, 2007; Reed et al, 1994; Small et al, 1999; Wetter et al, 2005; Zehnder et al, 2009). Conversely though, there is also evidence that cognitive performance is not affected by ε4 genotype in healthy adulthood (e.g., Bathum et al, 2006; Bunce, Fratiglioni, Small, Winblad, & Backman, 2004; Chen et al, 2002; Garcia et al, 2008; Jacobson et al, 2005; Kim et al, 2002; Marquis et al, 2002; Salo et al, 2001; Tohgi et al, 1997; Ystad et al, 2009), or that older ε4 carriers even show better cognitive performance (e.g., Carrion-Baralt et al, 2009). Thus, research on APOE ε4 in non-clinically-impaired cognitive functioning has produced mixed findings.…”