The aim of this study was to examine the structural change in the hippocampal subfields in early-onset (EO) mild cognitive impairment (MCI) patients associated with the APOE ε4 carrier state.

This study had 50 subjects aged 55-63 years, all of whom were diagnosed with amnestic MCI at baseline via the Korean version of the Consortium to Establish a Registry for Alzheimer’s Disease Assessment Packet (CERAD-K). The EO-MCI patients were divided into the MCI continued (MCIcont) and Alzheimer’s disease (AD) converted (ADconv) groups 2 years later. The volumes of hippocampal subfields were measured for all the subjects. The calculations were based on the change of the volumes between the 2-year-interval brain Magnetic resonance image (MRI) scans between MCIcont and ADconv groups according to the Apolipoprotein ε4 (APOE ε4) carrier state.

There was a significant correlation between APOE ε4 allele and structural changes in several hippocampal subfields. The volume reduction in cornus ammonis 1 (CA1) field and subiculum, especially in the APOE ε4 carriers. The significance was more prominent in ADconv group.

These results suggest that the possession of APOE ε4 allele may lead to significantly greater predilection for the structural changes in hippocampal subfields, showing significant changes, especially in the ADconv patients compared with MCIcont patients.

To examine the impact of determinants of incident dementia in three different old age groups (75–79, 80–84, 85+years) in Germany.

Multicenter prospective AgeCoDe/AgeQualiDe cohort study with baseline and nine follow-up assessments at 1.5-year intervals.

Primary care medical record registry sample.

General practitioners’ (GPs) patients aged 75+years at baseline.

Conduction of standardized interviews including neuropsychological assessment and collection of GP information at each assessment wave. We used age-stratified competing risk regression models (accounting for the competing event of mortality) to assess determinants of incident dementia and age-stratified ordinary least square regressions to quantify the impact of identified determinants on the age at dementia onset.

Among 3027 dementia-free GP patients, n = 704 (23.3%) developed dementia during the 13-year study period. Worse cognitive performance and subjective memory decline with related worries at baseline, and the APOE ε4 allele were associated independently with increased dementia risk in all three old age groups. Worse cognitive performance at baseline was also associated with younger age at dementia onset in all three age groups. Other well-known determinants were associated with dementia risk and age at dementia onset only in some or in none of the three old age groups.

This study provides further evidence for the age-specific importance of determinants of incident dementia in old age. Such specifics have to be considered more strongly particularly with regard to potential approaches of early detection and prevention of dementia.

There is little information on the association of the APOEe4 allele and AD risk in African populations. In previous analyses from the Indianapolis-Ibadan dementia project, we have reported that APOE ε4 increased the risk for Alzheimer's disease (AD) in African Americans but not in Yoruba. This study represents a replication of this earlier work using enriched cohorts and extending the analysis to include cognitive decline.

In this longitudinal study of two community dwelling cohorts of elderly Yoruba and African Americans, APOE genotyping was conducted from blood samples taken on or before 2001 (1,871 African Americans & 2,200 Yoruba). Mean follow up time was 8.5 years for African Americans and 8.8 years for Yoruba. The effects of heterozygosity or homozygosity of ε4 and of the possession of e4 on time to incident AD and on cognitive decline were determined using Cox's proportional hazards regression and mixed effects models.

After adjusting for covariates, one or two copies of the APOE ε4 allele were significant risk factors for incident AD (p < 0.0001) and cognitive decline in the African-American population (p < 0001). In the Yoruba, only homozygosity for APOE ε4 was a significant risk factor for AD (p = 0.0002) but not for cognitive decline (p = 0.2346), however, possession of an e4 allele was significant for both incident AD (p = 0.0489) and cognitive decline (p = 0.0425).

In this large longitudinal comparative study, APOE ε4 had a significant, but weaker, effect on incident AD and on cognitive decline in Yoruba than in African Americans. The reasons for these differences remain unclear.

Se is an essential trace element in human nutrition associated with antioxidant activity. Previous studies on predictors of toenail Se or serum Se have mostly concentrated on demographic factors such as age and gender. The present paper examines the association between apoE genotype and Se levels in nail samples in a rural elderly Chinese cohort.

Two thousand Chinese aged 65 years and over from four counties in China were enrolled in a cohort to study the association of Se with cognitive decline. Nail samples were collected from each participant and analysed for Se levels. Dietary Se intake was estimated from an FFQ using Se contents measured in food items collected from each village. Blood samples on filter cards were collected and analysed for apoE genotype. Mixed-effect models were constructed with nail Se level as the dependent variable and each village as the random effect, which controlled for the potential confounding effect from correlation in Se measures obtained from participants residing in the same village.

In this elderly Chinese cohort, carriers of the apoE ε4 allele had significantly lower Se levels measured in nail samples than non-carriers after adjusting for other significant covariates and controlling for estimated dietary Se intake. There was no significant difference between the two genotypes on estimated Se dietary intake (P = 0·6451).

Future studies are needed to examine the mechanism underlying the association between the apoE ε4 allele and Se levels, including the role of oxidative stress and that of reduced lipid metabolism in the apoE ε4 carriers.