Reduced Age-Related Cataracts Among Elderly Persons Who Reach Age 90 With Preserved Cognition: A Biomarker of Successful Aging?

Neuropsychological Test Norms in Cognitively Intact Oldest-Old

OBJECTIVES

Individuals aged 90 or older (oldest-old), the fastest growing segment of the population, are at increased risk of developing cognitive impairment compared with younger old. Neuropsychological evaluation of the oldest-old is important yet challenging in part because of the scarcity of test norms for this group. We provide neuropsychological test norms for cognitively intact oldest-old.

METHODS

Test norms were derived from 403 cognitively intact participants of The 90+ Study, an ongoing study of aging and dementia in the oldest-old. Cognitive status of intact oldest-old was determined at baseline using cross-sectional approach. Individuals with cognitive impairment no dementia or dementia (according to DSM-IV criteria) were excluded. Participants ranged in age from 90 to 102 years (mean=94). The neuropsychological battery included 11 tests (Mini-Mental Status Examination, Modified Mini-Mental State Examination, Boston Naming Test - Short Form, Letter Fluency Test, Animal Fluency Test, California Verbal Learning Test-II Short Form, Trail Making Tests A/B/C, Digit Span Forward and Backwards Test, Clock Drawing Test, CERAD Construction Subtests), and the Geriatric Depression Scale.

RESULTS

Data show significantly lower scores with increasing age on most tests. Education level, sex, and symptoms of depression were associated with performance on several tests after accounting for age.

CONCLUSIONS

Provided test norms will help to distinguish cognitively intact oldest-old from those with cognitive impairment. (JINS, 2019, 25, 530-545).

Cognitive functioning of individuals aged 90 years and older without dementia: A systematic review

INTRODUCTION

Reference values to define cognitive impairment in individuals aged 90 years and older are lacking. We systematically reviewed the literature to determine the level of cognitive functioning of individuals aged 90 years and older without dementia.

METHODS

The search identified 3972 articles of which 20 articles were included in the review. We calculated mean cognitive test scores and cut-off scores for cognitive tests published in two or more articles.

RESULTS

The mean cognitive test scores (SD)/cut-off scores for individuals aged 90 years and older without dementia of the five most commonly used cognitive tests were: MMSE: 26.6 (2.6)/23.3 points, Digit Span forward: 5.9 (1.8)/3.6 digits, Digit Span backward: 4.4 (1.6)/2.4 digits, TMT-A: 85.8 (42.5)/140.2s and TMT-B: 220.3 (99.2)/347.3s.

DISCUSSION

We provided mean cognitive test scores and cut-off scores that will improve the diagnostic process of cognitive impairment in individuals aged 90 years and older.

The association between gout and cataract risk: A meta-analysis

PURPOSE

To evaluate the relationship between gout and age-related cataracts (ARCs).

METHODS

A comprehensive literature search of the PubMed and Web of Science databases was conducted to identify papers on the association between gout and cataract risk that had been published between February 1991 and January 2017. Pooled relative risks (RRs) or odds ratios (ORs) and their corresponding 95% confidence intervals (CIs) were calculated. The random-effects model was used instead of the fixed-effects model when heterogeneity was identified, as indicated by a Cochran's Q statistic P-value <0.10 or I2 index score >50%.

RESULTS

A total of 3 cross-sectional studies and 3 case-control studies were included in the meta-analysis. Gout was significantly associated with increased odds of ARCs (OR 1.53, 95% CI 1.27-1.84). In the subgroup analysis, gout exhibited positive associations with the odds of posterior subcapsular cataracts (PSCs, OR 1.69, 95% CI: 1.06-2.70) and cortical cataracts (CCs, OR 1.39, 95% CI: 1.06-1.81). However, no association was identified between gout and the odds of nuclear cataracts.

CONCLUSIONS

The current literature suggested that gout may be associated with increased odds of ARCs, especially PSCs and CCs. Further efforts should be made to confirm these findings and clarify the effect of gout and gout medications on the development of cataracts.

Hormone-brain-aging relationships, broadly reactive with imidazole-containing dipeptides: targeting of telomere attrition as an aging biomarker and dynamic telomerase activity flirting

It has been documented that telomere-associated cellular senescence may contribute to certain age-related disorders, and telomere length (TL) may be an informative biomarker of healthy aging. Hormone-brain-aging behavior-modulated telomere dynamics and changes in telomerase activity are consistent elements of cellular alterations associated with changes in proliferative state, and these processes are consequently considered as the new therapeutic drug targets for physiological control with advanced drug delivery and nutritional formulations. We raise and support a therapeutic concept of using nonhydrolyzed forms of naturally occurring neuron-specific imidazole dipeptide-based compounds carnosine and carcinine, making it clinically possible that slowing down the rate of telomere shortening could slow down the human aging process in specific tissues where proliferative senescence is known to occur, with the demonstrated evidence of telomere shortening that appeared to be a hallmark of oxidative stress and disease. Carnosine released from skeletal muscle during exercise may be transported into the hypothalamic tuberomammillary nucleus (TMN) histamine neurons and hydrolyzed. The resulting L-histidine may subsequently be converted into histamine, which could be responsible for the effects of carnosine on neurotransmission and hormone-like antiaging physiological function. The preliminary longitudinal studies of elderly individuals suggest that longer telomeres are associated with better survival, and an advanced oral nutritional support with nonhydrolyzed carnosine (or carcinine and patented compositions thereof) is a useful therapeutic tool for a critical TL maintenance that may fundamentally be applied in the treatment of age-related sight-threatening eye disorders, prolonged life expectancy, increased survival and chronological age of an organism in health control, smoking behavior, and disease. "Our pleasures were simple-they included survival." -Dwight D. Eisenhower, 34th President of the United States, 1953-1961.

Age-related cataract in dogs: a biomarker for life span and its relation to body size

Clinical data from 72 dog breeds of varying size and life expectancy were grouped according to breed body mass and tested for prevalence at ages 4 to 5, ages 7 to 10, and lifetime incidence of non-hereditary, age-related cataract (ARC). The incidence of ARC was found to be directly related to the relative life expectancies in the breed groups: The smallest dog breeds had a lower ARC prevalence between ages 4 and 5 than mid-size breeds and these, in turn, a lower prevalence than the giant breeds. A similar sequence was evident for ages 7 to 10 and for overall lifetime incidence of ARC. These differences became more significant when comparing small and giant breeds only. We could also confirm the inverse relationship between body size and life expectancy in these same sets of dog breeds. Our results show that body size, life expectancy, and ARC incidence are interrelated in dogs. Given that ARC has been shown to be at least partially caused by oxidative damage to lens epithelial cells and the internal lens, we suggest that it can be considered not only as a general biomarker for life expectancy in the canine and possibly other species, but also for the systemic damages produced by reactive oxygen species. This suggests new approaches to examine the gene expression pathways affecting the above-noted linkages.

EPHA2 is associated with age-related cortical cataract in mice and humans

Age-related cataract is a major cause of blindness worldwide, and cortical cataract is the second most prevalent type of age-related cataract. Although a significant fraction of age-related cataract is heritable, the genetic basis remains to be elucidated. We report that homozygous deletion of Epha2 in two independent strains of mice developed progressive cortical cataract. Retroillumination revealed development of cortical vacuoles at one month of age; visible cataract appeared around three months, which progressed to mature cataract by six months. EPHA2 protein expression in the lens is spatially and temporally regulated. It is low in anterior epithelial cells, upregulated as the cells enter differentiation at the equator, strongly expressed in the cortical fiber cells, but absent in the nuclei. Deletion of Epha2 caused a significant increase in the expression of HSP25 (murine homologue of human HSP27) before the onset of cataract. The overexpressed HSP25 was in an underphosphorylated form, indicating excessive cellular stress and protein misfolding. The orthologous human EPHA2 gene on chromosome 1p36 was tested in three independent worldwide Caucasian populations for allelic association with cortical cataract. Common variants in EPHA2 were found that showed significant association with cortical cataract, and rs6678616 was the most significant in meta-analyses. In addition, we sequenced exons of EPHA2 in linked families and identified a new missense mutation, Arg721Gln, in the protein kinase domain that significantly alters EPHA2 functions in cellular and biochemical assays. Thus, converging evidence from humans and mice suggests that EPHA2 is important in maintaining lens clarity with age.

Cataract is the leading cause of blindness. Cataract may form at any age, but the peak incidence is bimodal—in the perinatal period or later than 50 years of age. The early onset forms follow Mendelian inheritance patterns and are rare. Age-related cataract accounts for 18 million cases of blindness and 59 million cases of reduced vision worldwide. Among three types of age-related cataract, cortical cataract is known to be highly heritable, although few genes have been linked to its etiology. We report here that EPHA2 is associated with cortical cataract. EPHA2 is expressed in mouse and human cortical lens fiber cells, and homozygous deletion of Epha2 in two independent strains of mice led to development of cataract that progressed with age. Common and rare variants including a missense mutation in the EPHA2 gene were associated for cortical cataract in three different Caucasian populations. Our study identified EPHA2 as a gene for human age-related cataract and established Epha2 knockout mice as a model for progressive cortical cataract.

Population-based studies in ophthalmology

PURPOSE

To review major findings of population-based studies in ophthalmology, to summarize key questions, and to highlight future directions for this study design.

DESIGN

Summary and critical analysis of major population-based studies in eye diseases.

METHODS

Literature review and interpretation.

RESULTS

In the last 30 years, there have been many population-based studies in ophthalmology conducted in the United States and other countries around the world. These studies have provided information on the epidemiology of visual loss and the major eye diseases associated with visual loss; the risk factors; and the socioeconomic burden of eye disease. Population-based studies remain the most valid to determine the prevalence and incidence of a disease, and the population-attributable risk of new risk factors, including the interaction of genetic markers with systemic and environmental factors. Repeated surveys over time may also demonstrate impact of preventive strategies.

CONCLUSIONS

Population-based studies have provided substantial data on the frequency and impact of the major eye diseases in the community. This study design will continue to have an important role in addressing key questions of why eye diseases occur, who is at highest risk, and what preventive and therapeutic strategies are necessary to eliminate these diseases.