Time-averaged MSD of Brownian motion

We study the statistical properties of the time-averaged mean-square displacements (TAMSD). This is a standard non-local quadratic functional for inferring the diffusion coefficient from an individual random trajectory of a diffusing tracer in single-particle tracking experiments. For Brownian motion, we derive an exact formula for the Laplace transform of the probability density of the TAMSD by mapping the original problem onto chains of coupled harmonic oscillators. From this formula, we deduce the first four cumulant moments of the TAMSD, the asymptotic behavior of the probability density and its accurate approximation by a generalized Gamma distribution

APOE Genotype Influences Functional Status among Elderly without Dementia

The presence of apolipoprotein-ϵ4 (APOE-ϵ4) significantly increases the risk of Alzheimer's disease (AD). The association between APOE-ϵ4 status and functional abilities was explored further in a multicultural sample of community-dwelling, non-demented elders. The sample was limited to cognitively-intact, community-dwelling elders, who were free of stroke or other neurologic disability. In 218 elders who met research criteria, the presence of APO-ϵ4 was associated with poorer functional status, apart from the effects of neuropsychological performance, gender, age, and education (OR = 2.5, 95% CI: 1.3, 4.9). In 158 subjects without an APOE-ϵ4 allele, 50% reported no functional limitation; in the 60 subjects with an ϵ4 allele, only 28% reported no functional limitation (P < .01). The relationship was not explained by the distribution of co-morbidities. The association between poorer function and the presence of an APOE-ϵ4 allele was evident in each ethnic group. In path analyses, the presence of an APOE-ϵ4 allele was associated with decreased functional ability in non-demented elders not simply through an association with poorer cognitive status, but also independently. These results suggest that the APOE-ϵ4 genotype is associated with functional deficit in people with normal neuropsychological profiles

Influence of Education and Occupation on the Incidence of Alzheimer's Disease

Objective. —Several cross-sectional studies have found an association between Alzheimer's disease (AD) and limited educational experience. It has been difficult to establish whether educational experience is a risk factor for AD because educational attainment can influence performance on diagnostic tests. This study was designed to determine whether limited educational level and occupational attainment are risk factors for incident dementia. Design. —Cohort incidence study. Setting. —General community. Participants. —A total of 593 nondemented individuals aged 60 years or older who were listed in a registry of individuals at risk for dementia in North Manhattan, NY, were identified and followed up. Interventions. —We reexamined subjects 1 to 4 years later with the identical standardized neurological and neuropsychological measures. Main Outcome Measure. —Incident dementia. Results. —We used Cox proportional hazards models, adjusting for age and gender, to estimate the relative risk (RR) of incident dementia associated with low educational and occupational attainment. Of the 593 subjects, 106 became demented; all but five of these met research criteria for AD. The risk of dementia was increased in subjects with either low education (RR, 2.02; 95% confidence interval [CI], 1.33 to 3.06) or low lifetime occupational attainment (RR, 2.25; 95% CI, 1.32 to 3.84). Risk was greatest for subjects with both low education and low life-time occupational attainment (RR, 2.87; 95% CI, 1.32 to 3.84). Conclusions. —The data suggest that increased educational and occupational attainment may reduce the risk of incident AD, either by decreasing ease of clinical detection of AD or by imparting a reserve that delays the onset of clinical manifestations

Genetic Susceptibility and Head Injury as Risk Factors for Alzheimer's Disease among Community-Dwelling Elderly Persons and Their First-Degree Relatives

We performed a community-based study to investigate the relationship of genetic susceptibility and head injury to Alzheimer's disease(AD) in 138 patients with AD and 193 healthy elderly control subjects. Data concerning presence or absence of dementia and certain exposures were also obtained from 799 first-degree relatives of the patients and 1,238 first-degree relatives of the control subjects. Adjusting for age, gender, and other risk factors, the odds ratio for AD associated with head injury was 3.7 (95% confidence interval [CI], 1.4–9.7). The association was highest for head injuries that occurred after age 70. The risk of AD was higher in first-degree relatives of patients with onset prior to age 70 than in relatives of control subjects (risk ratio [RR] = 2.5; 95% CI, 1.1–5.6). The risk was not increased for relatives of patients with onset of AD at age 70 or older. Compared with relatives without head injury, the risk of AD was increased among both head-injured relatives of patients (RR = 5.9; 95% CI, 2.3–14.8) and head-injured relatives of control subjects (RR = 6.9; 95% CI, 2.5–18.9). Our results are consistent with the hypothesis that severe head injury and genetic susceptibility are associated with AD. Both associations concur with current concepts regarding the role of amyloid in AD. Although we regard head injury, like genetic susceptibility, to be a putative risk factor for AD, the temporal relationship between head injury and AD warrants further investigation

Depressed Mood and the Incidence of Alzheimer's Disease in the Elderly Living in the Community

BACKGROUND: It remains unclear whether depression increases the risk for dementia in the elderly. We evaluated the relationship between depressed mood at baseline and the incidence of dementia, particularly Alzheimer's disease, in the elderly living in the community. METHODS: A total of 1070 elderly individuals, aged 60 years or older, were identified as part of a registry for dementia in the Washington Heights community of North Manhattan, NY. In a prospective, longitudinal design with follow-up for 1 to 5 years, annual physician evaluation and neuropsychological testing were used to assess levels of cognitive impairment and to diagnose dementia. Depressive symptoms were evaluated with the 17-item Hamilton Rating Scale for Depression. Based on clinical considerations and a validity study, a positive score for the depressed mood item was used in statistical analyses. To confirm the results, the total Hamilton Rating Scale for Depression score was also evaluated as the "depression" variable. RESULTS: Of the 1070 subjects, 218 met criteria for dementia at baseline evaluation. In the 852 subjects without dementia, depressed mood was more common in individuals with greater cognitive impairment. In a follow-up study of 478 of these subjects without dementia (mean +/- SD, 2.54 +/- 1.12 years of follow-up), the effect of baseline depressed mood on the end- point diagnosis of dementia (93% had possible or probable Alzheimer's disease) was evaluated in a Cox proportional hazards model. Depressed mood at baseline was associated with an increased risk of incident dementia (relative risk, 2.94; 95% confidence interval, 1.76 to 4.91; P .001). This effect remained after adjustment for age, gender, education, language of assessment, Blessed Memory Information and Concentration test scores, and Blessed Functional Activity Scale scores (relative risk, 2.05; 95% confidence interval, 1.16 to 3.62; P .02). Similar results were obtained when the total Hamilton Rating Scale for Depression score was used as the depression variable, with the use of the same covariates (relative risk, 1.07 per point interval; 95% confidence interval, 1.02 to 1.11; P .01). CONCLUSIONS: Depressed mood moderately increased the risk of developing dementia, primarily Alzheimer's disease. Whether depressed mood is a very early manifestation of Alzheimer's disease, or increases susceptibility through another mechanism, remains to be determined

Prevalence and Characteristics of Anergia (Lack of Energy) in Patients With Acute Coronary Syndrome

Anergia, a commonly occurring syndrome in older adults and patients with cardiovascular diseases, is associated with functional and clinical limitations. To date, the prevalence and clinical–demographic characteristics of anergia in patients with acute coronary syndrome (ACS) have not been elucidated. We examined the prevalence and clinical–demographic characteristics of anergia in a multiethnic sample of patients with ACS. Hospitalized patients with ACS (n = 472), enrolled in the Prescription Usage, Lifestyle, and Stress Evaluation (PULSE) prospective cohort study, completed assessments of demographic, behavioral, and clinical characteristics within 7 days of hospitalization for an ACS event. Current depressive disorder was ascertained using a structured psychiatric interview 3 to 7 days after discharge. Anergia was assessed at baseline and defined using patients' binary responses (yes/no) to 7 items related to energy level. At least 1 complaint of anergia was reported by 79.9% of patients (n = 377) and 32% of patients (n = 153) met criteria for anergia. In a multivariable logistic regression model, anergia was independently associated with being a woman, being white (compared to black), having bodily pain, participating in exercise, having current depressive disorder, and having higher values on the Charlson Co-morbidity Index. In conclusion, anergia is a highly prevalent syndrome in patients with ACS. It is distinct from depression and is associated with modifiable clinical factors such as participation in exercise and bodily pain that may be appropriate targets for intervention

Validation and factor structure of the Thai version of the EURO-D scale for depression among older psychiatric patients

Objectives: To assess the concurrent and the construct validity of the Euro-D in older Thai persons

Apolipoprotein E and Alzheimer's Disease: Ethnic Variation in Genotypic Risks

The presence of the apolipoprotein E4 (apo €4) allele significantly increases the risk of Alzheimer's disease. Whether this is due to biological effects of the apo E4 protein or reflects linkage disequilibrium with an as yet unidentified Alzheimer's disease susceptibility gene is of critical importance. In a community study in northern Manhattan we found a fivefold increase in the risk of Alzheimer's disease among African-Americans, Hispanics, and whites homozygous for apo ~4. Overall, the risk between Alzheimer's disease and apo ~4 heterozygosity was also increased by twofold, but the association was somewhat weaker for African-Americans than for Hispanics and whites. In contrast, the apo e2/~3 genotype was associated with an eightfold increased risk of Alzheimer's disease in African-Americans but it was associated with reduced risk in whites. Variability in the strength and type of association between Alzheimer's disease and the apo E polymorphisms in the three ethnic groups could not be fully explained by age differences. The allelic frequency of apoe"4 was significantly higher in patients than control subjects in all ethnic groups at age 70 or younger, reflecting the higher proportion of apo E4 homozygotes, but this difference diminished with increasing age. The allelic frequency of apoe'2 for African-Americans and Hispanics, but not whites, was significantly higher in patients than control subjects, but only after age 70. Though these findings need confirmation, they suggest that modifier genes or environmenral factors may interact selectively with apo E4 in African-Americans to weaken the association with Alzheimer's disease or that the apo E allelic system is in linkage disequilibrium with a nearby, as yet unidentified Alzheimer's disease susceptibility locus

Boundary driven zero-range processes in random media

The stationary states of boundary driven zero-range processes in random media with quenched disorder are examined, and the motion of a tagged particle is analyzed. For symmetric transition rates, also known as the random barrier model, the stationary state is found to be trivial in absence of boundary drive. Out of equilibrium, two further cases are distinguished according to the tail of the disorder distribution. For strong disorder, the fugacity profiles are found to be governed by the paths of normalized $\alpha$-stable subordinators. The expectations of integrated functions of the tagged particle position are calculated for three types of routes.Comment: 23 page