Apolipoprotein E genotype and cognition in the very old

Sleep Polygenic Risk Score Is Associated with Cognitive Changes over Time

Sleep problems have been associated with cognition, both cross-sectionally and longitudinally. Specific genes have been also associated with both sleep regulation and cognition. In a large group of older non-demented adults, we aimed to (a) validate the association between Sleep Polygenic Risk Score (Sleep PRS) and self-reported sleep duration, and (b) examine the association between Sleep PRS and cognitive changes in a three-year follow-up. Participants were drawn from the Hellenic Longitudinal Investigation of Aging and Diet (HELIAD). A structured, in-person interview, consisting of a medical history report and physical examination, was conducted for each participant during each of the visits (baseline and first follow-up). In total, 1376 participants were included, having all demographic, genetic, and cognitive data, out of which, 688 had at least one follow-up visit. In addition, an extensive neuropsychological assessment examining five cognitive domains (memory, visuo-spatial ability, attention/speed of processing, executive function, and language) was administered. A PRS for sleep duration was created based on previously published, genome-wide association study meta-analysis results. In order to assess the relationship between the Sleep PRS and the rate of cognitive change, we used generalized estimating equations analyses. Age, sex, education, ApolipoproteinE-ε4 genotype status, and specific principal components were used as covariates. On a further analysis, sleep medication was used as a further covariate. Results validated the association between Sleep PRS and self-reported sleep duration (B = 1.173, E-6, p = 0.001). Further, in the longitudinal analyses, significant associations were indicated between increased Sleep PRS and decreased visuo-spatial ability trajectories, in both the unadjusted (B = -1305.220, p = 0.018) and the adjusted for the covariates model (B = -1273.59, p = 0.031). Similarly, after adding sleep medication as a covariate (B = -1372.46, p = 0.019), none of the associations between Sleep PRS and the remaining cognitive domains were significant. PRS indicating longer sleep duration was associated with differential rates of cognitive decline over time in a group of non-demented older adults. Common genetic variants may influence the association between sleep duration and healthy aging/cognitive health.

Association between apolipoprotein E ε4 and longitudinal cognitive decline: nested case-control study among chinese community-dwelling elders

BACKGROUND/AIMS

Cognitive decline in the elderly is an early predictor of dementia. The apolipoprotein E (APOE) ε4 allele is considered an important genetic determinant of Alzheimer's disease (AD), and strongly suspected to play a role in cognitive variation. However, its effects upon predicting the progression of cognitive decline more generally remain unclear. Our aim was to explore the role of APOE ε4 in longitudinal cognitive decline, considering sociodemographics, vascular disease, and lipid profile.

METHODS

We chose a nested case-control design, and prospectively collected demographic and clinical data, determined APOE genotypes, and obtained follow-up information on cognitive variation (measured by a spectrum of cognitive tests) for 3 years. Cognitive decline was predefined as an increase in Clinical Dementia Rating Scale class, or at least a 4-point decrease (>1 SD) in MMSE, between baseline and follow-ups.

RESULTS

Among 600 follow-up subjects with mild cognitive impairment and aged 65 years or older, 114 pairs of cognitive decline and stable subjects were identified and matched for sex, age, and educational level in a 1:1 ratio. The APOE ε4 frequency in the cognitive decline group was significantly higher than that in the stable group (p < 0.05), while the APOE ε2 and ε3 prevalence in the cognitive decline group did not differ significantly from that in controls (p > 0.05). At the first follow-up, modest but significant declines only in the memory domain were associated with APOE ε4. At the last follow-up, significant associations were noted between APOE ε4 and cognitive decline from 5 of the 6 cognitive outcomes, which included story recall, memory, spatial recognition, naming, and sustained attention. Conditional logistic regression showed that the presence of APOE ε4 was significantly associated with the cognitive decline group, as compared to the stable group, adjusting for vascular diseases and lipid profile.

CONCLUSIONS

APOE ε4 offered information on the risk of cognitive decline in this longitudinal study, and may exert detectable effects early in a long prodromal AD trajectory.

Memory performance and the apolipoprotein E polymorphism in a community sample of middle-aged adults

The apolipoprotein E genotype (APOE) is an established risk factor for Alzheimer disease, with the age-at-onset occurring earlier in individuals having at least one APOE epsilon 4 allele, relative to the APOE epsilon 3 or APOE epsilon 2 isoforms. Moreover, nondemented older adults with the APOE epsilon 4 allele also show diminished cognitive performance, particularly on tests of learning and memory, and an accelerated decline in memory performance with increasing age. The current investigation extends the study of the APOE epsilon 4 allele and cognitive performance to healthy, middle-aged adults. A community sample of 220 non-Hispanic Caucasian men and women, aged 24-60 (average age = 46), were genotyped for the APOE polymorphism and completed a battery of neuropsychological tests. Multivariate analyses were conducted on measures of verbal learning and memory (e. g., learning a list of words and recalling them 30 min later), visual memory (e.g., reproducing a previously copied figure from memory), and attention span (e.g., repeating long lists of digits), after adjustments for age, and estimated IQ. Results indicated that performance on learning and memory tasks was significantly poorer in adults having any APOE epsilon 4 allele, relative to adults with APOE epsilon 2 and epsilon 3 genotypes (P <.01). Attention span did not differ by genotype. These findings, the first in a sample of middle-aged adults, suggest that the APOE polymorphism is a marker for age-related decline in memory (detectable prior to overt, clinical manifestations of memory loss), and/or a marker for individual differences in memory ability across the life span. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:707-711, 2000.

Cognitive function and apolipoprotein E in very old adults: findings from the Nun Study

OBJECTIVES

The epsilon4 allele of apolipoprotein E (APOE) has been associated with Alzheimer' s disease and with milder forms of cognitive impairment. We investigated the possibility that the absence of the epsilon4 allele may predict the maintenance of high cognitive function among very old individuals.

METHODS

Our data are from the Nun Study, a longitudinal study of aging and Alzheimer's disease in 678 Catholic sisters. All sisters participate in annual functional exams that include the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) battery of cognitive tests. High cognitive function was defined as intact scores on five of the CERAD tests. A total of 241 participants aged 75 to 98 met this criterion at the first exam.

RESULTS

Findings showed that 62% of the 241 participants maintained intact scores on the five CERAD tests throughout their participation in the study. Life table analyses indicated that those without the APOE epsilon4 allele spent more time with intact cognitive function than those with the epsilon4 allele (p = .007). Cox regression analyses indicated that those without the epsilon4 allele had half the risk of losing their intact status during the study when compared with those with the epsilon4 allele (p < .01).

DISCUSSION

Our findings suggest that the APOE epsilon4 allele may be included among the variables that predict high cognitive function in cognitively intact, very old adults. Although the presence or absence of the epsilon4 allele is known to be related to the risk of dementia, it also appears to be related to maintaining high levels of cognitive function in old age.

The relationship between apolipoprotein E, dementia, and vascular illness

The purpose of this study was to concurrently assess the relationship of Apolipoprotein E (APOE) with both dementias and vascular illnesses in the very old. Nine hundred and fifty nine subjects (mean age 85 years) in a long-term care facility were genotyped and cognitively tested with the Mini Mental State Exam. All subjects were studied for the relationship of APOE with atherosclerotic heart disease, hypertension, or stroke without concomitant dementia. Four hundred fifty individuals met criteria for inclusion into one of the following groups: Alzheimer's disease (n = 318), vascular dementia (n = 49), or not demented controls (n = 83) and were investigated for the relationship between APOE and these diagnostic categories. APOE epsilon4 was not associated with atherosclerotic heart disease, hypertension, or stroke without concomitant dementia. The APOE epsilon3 allele was more common in men with atherosclerotic heart disease. In contrast, the APOE epsilon4 allele was more common in patients with Alzheimer's disease (22%) and vascular dementia (26%) than in not demented controls (7%). APOE epsilon4 is associated with dementias in the very old, whereas its relationship with either peripheral or central nervous system vascular disease without dementia is not as robust.

Apolipoprotein E and longevity among Han Chinese population

The apolipoprotein E gene (APOE), which locates on chromosome 19, has three common APOE alleles encoding APOE*2, APOE*3, APOE*4. It has been considered to be closely associated with human longevity among Western population. However, the allele frequency varies among racial and ethnic groups. We studied the relationship between APOE and longevity among 1562 Han Chinese (246 female and 1316 male) whose ages ranged from 20-108 years old in Shanghai metropolitan area and Lian Yungang, Jiangsu province. APOE was amplified by one-stage PCR using the forward primer: 5'-GGC ACG GCT GTC CAA GGA GCT-3' and reverse primer: 5'-GAT GGC GCT GAG GCC GCG CT-3'. The PCR product was digested directly with 5 U of CfoI and separated by a 20% polyacrylamide (acrylamide:bisacrylamide = 29:1) nondenaturing gel. The allele frequency of APOE*4 in thevery old age group (> or = 85 years) was significantly different from that in the youth (20-39 years), middle (40-59 years) and old (60-84 years) age group (2.5% vs 8.4, 7.9 or 7.6%; P < 0.05), respectively.