APOE ε4 is not associated with Alzheimer's Disease in elderly Nigerians
ABSTRACT Since 1992, research teams from Indiana University and the University of Ibadan have been collecting and comparing data from two diverse, elderly populations to identify risk factors for dementia and Alzheimer's disease. Apolipoprotein E (APOE) was genotyped in 2,245 Nigerian samples. Of these, 830 had a diagnosis: 459 were normal, and 140 had dementia including 123 diagnosed with Alzheimer's disease. In contrast with other populations, the APOE epsilon4 allele was not significantly associated with Alzheimer's disease or dementia. This lack of association in the Yoruba might reflect genetic variation, environmental factors, as well as genetic/environmental interactions.
Full-textDOI: · Available from: Sujuan Gao, Apr 11, 2014
- SourceAvailable from: Maëlenn Guerchet
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- "In this study, the presence of depressive symptoms at the time of the survey was significantly associated with dementia. This factor has already been associated with cognitive impairment in another elderly African population . The relationship between depression and dementia is discussed in the literature   , but it remains controversial whether depressive symptoms represent a risk factor for dementia, or if they are an early symptom of neurodegeneration or a response to first cognitive deficit symptoms. "
ABSTRACT: Risk factors for dementia in American and European countries have been well investigated. However, little research has been carried out in sub-Saharan Africa, where life events as well as environmental, socio-economic, and modifiable risk factors (i.e., cardiovascular risk factors) may differ. Two cross-sectional surveys were conducted in representative samples of the older general population living in Bangui (Central African Republic) and Brazzaville (Congo). Dementia was defined according to the DSM-IV criteria. Multivariate regression analyses were performed in order to identify independent factors associated with dementia. Among the 977 elderly Africans included in this analysis, 75 (7.6%) were diagnosed as having dementia. Increasing age, female gender, hypertension, a body mass index <18.5 kg/m2, depressive symptoms, and the lack of a primary education were significantly associated with dementia. Among life events, the death of one parent during childhood and recently having moved house were also associated with dementia. Beyond the usual risk factors for dementia, this study highlights the role of stressful events in low-income countries. Factors associated with dementia in African countries seem different from established factors in high-income countries and require further investigation.Journal of Alzheimer's disease: JAD 12/2011; 29(1):15-24. DOI:10.3233/JAD-2011-111364 · 4.15 Impact Factor
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- "Ethnicity is also important, and for genes of interest with respect to cognitive aging such as APOE, there are major differences in allele frequencies between ethnic groups. At least in the context of pathology these variations have different associations with risk, so that a population with a high incidence of APOE ε4 may show a weak effect of ε4 carrier status on risk of dementia (Gureje et al., 2006), which in other populations are associated with a high risk effect (Raber et al., 2004). These are general issues affecting the whole field of cognitive and neuropsychiatric genetics. "
ABSTRACT: Knowledge of genetic influences on cognitive aging can constrain and guide interventions aimed at limiting age-related cognitive decline in older adults. Progress in understanding the neural basis of cognitive aging also requires a better understanding of the neurogenetics of cognition. This selective review article describes studies aimed at deriving specific neurogenetic information from three parallel and interrelated phenotype-based approaches: psychometric constructs, cognitive neuroscience-based processing measures, and brain imaging morphometric data. Developments in newer genetic analysis tools, including genome wide association, are also described. In particular, we focus on models for establishing genotype-phenotype associations within an explanatory framework linking molecular, brain, and cognitive levels of analysis. Such multiple-phenotype approaches indicate that individual variation in genes central to maintaining synaptic integrity, neurotransmitter function, and synaptic plasticity are important in affecting age-related changes in brain structure and cognition. Investigating phenotypes at multiple levels is recommended as a means to advance understanding of the neural impact of genetic variants relevant to cognitive aging. Further knowledge regarding the mechanisms of interaction between genetic and preventative procedures will in turn help in understanding the ameliorative effect of various experiential and lifestyle factors on age-related cognitive decline.Frontiers in Aging Neuroscience 11/2010; 2:143. DOI:10.3389/fnagi.2010.00143 · 2.84 Impact Factor
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- "sso - ciated with AD ( Heckmann et al . , 2004 ) , the APOE 4 allele also does not appear to increase risk of AD in certain com - munities with high consangunity such as the Wadi Ara Arabs in North Israel ( Farrer et al . , 2003 ) . The lack of effect of 4 allele as a susceptibility factor for probable AD in Yoruba , Bantu and Nilotic Africans ( Gureje et al . , 2006 ; Heckmann et al . , 2004 ; Osuntokun et al . , 1995 ; Sayi et al . , 1997 ) is unclear . The 4 allele has been suggested to be the ' thrifty ' allele in that exposure of APOE 4 to the contemporary envi - ronmental conditions including dietary habits and sedentary life styles could have induced it a susceptibility factor for AD and co"
ABSTRACT: Previous studies have established cross-cultural methods to screen for ageing- related dementia and susceptibility genes, in particular Alzheimer's disease (AD) among the Canadian Cree, African Americans and Yoruba in Nigeria. We determined whether the Community Screening Interview for Dementia (CSID), translated into Kikuyu, a major language of Kenya, could be used to evaluate dementia of the Alzheimer type. Using two sets of coefficients of cognitive and informant scores, two discriminant function (DF) scores were calculated for each of 100 elderly (>65 years) Nyeri Kenyans. When the cut-off points were selected for 100% sensitivities, the specificities of the DF scores were remarkably similar (93.75%) in the Kenyan sample. We propose the adapted CSID can be utilised to detect dementia among East Africans. We also show that apolipoprotein E epsilon 4 allele frequencies were high (approximately 30%) and not different between normal subjects and those with probable AD. There was no evidence to suggest years of education or vascular factors were associated with dementia status.Neurobiology of aging 09/2008; 31(5):732-40. DOI:10.1016/j.neurobiolaging.2008.06.014 · 4.85 Impact Factor