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Age-related changes in memory are not uniform, even in the absence of dementia. Characterization of non-disease associated cognitive changes is crucial to gain a more complete understanding of brain aging. Episodic memory was investigated in 13,037 ethnically diverse elderly (ages 72 to 85 years) with two to 15 years of follow-up, and with known dementia status, age, sex, education, and APOE genotypes. Adjusted trajectories of episodic memory performance over time were estimated using Latent Class Mixed Models. Analysis was conducted using two samples at baseline evaluation: i) non-cognitively impaired individuals, and ii) all individuals regardless of dementia status. We calculated the age-specific annual incidence rates of dementia in the non-demented elderly (n = 10,220). Two major episodic memory trajectories were estimated: 1) Stable-consisting of individuals exhibiting a constant or improved memory function, and 2) Decliner-consisting of individuals whose memory function declined. The majority of the study participants maintain their memory performance over time. Compared to those with Stable trajectory, individuals characterized as Decliners were more likely to have non-white ethnic background, fewer years of education, a higher frequency of ε4 allele at APOE gene and five times more likely to develop dementia. The steepest decline in episodic memory was observed in Caribbean-Hispanics compared to non-Hispanic whites (p = 4.3 x 10(-15)). The highest incident rates of dementia were observed in the oldest age group, among those of Caribbean-Hispanics ancestry and among Decliners who exhibited rates five times higher than those with Stable trajectories (11 per 100 person-years versus 3 per 100 person-years. Age, education, ethnic background and APOE genotype influence the maintenance of episodic memory. Declining memory is one of the strongest predictors of incident dementia.

[Objectives] Under existing technical conditions, fleet formation is optimized in order to improve the cooperative detection performance of a fleet against hostile submarines. [Methods] The coverage index is defined as a measure of submarine detection ability. Taking a naval combat formation for antisubmarine warfare as the research object, based on the theory of the probability formula of the joint detection performance of multiple ships and taking the maximization of the coverage area as the goal, a formation optimization model based on antisubmarine detection ability is established. An integral optimization method based on the probability distance function is designed to solve the model, and a reasonable formation scheme is obtained. [Results] The simulation results show that the coverage area changes regularly with the variation of the distribution distance of the ship. Under the same fleet size, the detection performance of herringbone formation or wedge-shaped formation is better than that of a single horizontal formation or azimuth team formation under optimal distribution spacing. In addition, the optimal distribution spacing decreases with the increase of the detection probability threshold. As the scale of the fleet increases, the coverage area increases correspondingly in a linear manner. [Conclusions] This model can effectively improve the capability of fleet searching and provide a decision basis for the use and deployment of surface ships in a potential search force.

Identifying genes underlying memory function will help characterize cognitively resilient and high‐risk declining subpopulations contributing to precision medicine strategies. We estimated episodic memory trajectories in 35,245 ethnically diverse older adults representing eight independent cohorts. We conducted apolipoprotein E (APOE)‐stratified genome‐wide association study (GWAS) analyses and combined individual cohorts' results via meta‐analysis. Three independent transcriptomics datasets were used to further interpret GWAS signals. We identified DCDC2 gene significantly associated with episodic memory (Pmeta = 3.3 x 10‐8) among non‐carriers of APOE ε4 (N = 24,941). Brain transcriptomics revealed an association between episodic memory maintenance and (1) increased dorsolateral prefrontal cortex DCDC2 expression (P = 3.8 x 10‐4) and (2) lower burden of pathological Alzheimer's disease (AD) hallmarks (paired helical fragment tau P =.003, and amyloid beta load P =.008). Additional transcriptomics results comparing AD and cognitively healthy brain samples showed a downregulation of DCDC2 levels in superior temporal gyrus (P =.007) and inferior frontal gyrus (P =.013). Our work identified DCDC2 gene as a novel predictor of memory maintenance. [ABSTRACT FROM AUTHOR]

Background: Genetic studies of Alzheimer's disease (AD) have focused on the clinical or pathological diagnosis as the primary outcome, but little is known about the genetic basis of the preclinical phase of the disease. Our goal was to identify the underlying genetic bases for brain amyloidosis during the preclinical phase of AD. Method: We performed genome‐wide association studies of positron emission tomography (PET) amyloid levels and meta‐analyzed the results. Genetic and imaging data were acquired from ten cohorts of primarily non‐demented individuals. The largest cohort, the A4 study (n = 3,154) was a secondary prevention trial designed to slow cognitive decline associated with brain amyloidosis. The other, smaller longitudinal cohort studies, similar in design, provided additional amyloid PET data with existing genetic data (n = 1,160 analyzed and n = 550 currently being analyzed). Result: We identified a locus for amyloidosis within RBFOX1 in addition to APOE along with several loci nearing significance. Conclusion: Multiple genetic loci may be associated with brain amyloidosis. Further research into these specific loci and genes will help in our understanding of the molecular bases of amyloid buildup in the brain. [ABSTRACT FROM AUTHOR]

Identifying genes underlying memory function will help characterize cognitively resilient and high-risk declining subpopulations contributing to precision medicine strategies. We estimated episodic memory trajectories in 35,245 ethnically diverse older adults representing eight independent cohorts. We conducted apolipoprotein E (APOE)-stratified genome-wide association study (GWAS) analyses and combined individual cohorts' results via meta-analysis. Three independent transcriptomics datasets were used to further interpret GWAS signals. We identified DCDC2 gene significantly associated with episodic memory (Pmeta = 3.3 x 10 -8 ) among non-carriers of APOE ε4 (N = 24,941). Brain transcriptomics revealed an association between episodic memory maintenance and (1) increased dorsolateral prefrontal cortex DCDC2 expression (P = 3.8 x 10 -4 ) and (2) lower burden of pathological Alzheimer's disease (AD) hallmarks (paired helical fragment tau P = .003, and amyloid beta load P = .008). Additional transcriptomics results comparing AD and cognitively healthy brain samples showed a downregulation of DCDC2 levels in superior temporal gyrus (P = .007) and inferior frontal gyrus (P = .013). Our work identified DCDC2 gene as a novel predictor of memory maintenance., (© 2021 the Alzheimer's Association.)