Temporal Trends in the Level and Decline of Cognition and Disability in an Elderly Population: The PAQUID Study

Today's Older Adults Are Cognitively Fitter Than Older Adults Were 20 Years Ago, but When and How They Decline Is No Different Than in the Past

History-graded increases in older adults' levels of cognitive performance are well documented, but little is known about historical shifts in within-person change: cognitive decline and onset of decline. We combined harmonized perceptual-motor speed data from independent samples recruited in 1990 and 2010 to obtain 2,008 age-matched longitudinal observations (M = 78 years, 50% women) from 228 participants in the Berlin Aging Study (BASE) and 583 participants in the Berlin Aging Study II (BASE-II). We used nonlinear growth models that orthogonalized within- and between-person age effects and controlled for retest effects. At age 78, the later-born BASE-II cohort substantially outperformed the earlier-born BASE cohort (d = 1.20; 25 years of age difference). Age trajectories, however, were parallel, and there was no evidence of cohort differences in the amount or rate of decline and the onset of decline. Cognitive functioning has shifted to higher levels, but cognitive decline in old age appears to proceed similarly as it did two decades ago.

Secular Trends in Dementia Free Cognitive Function in Older Adults: A Systematic Review

BACKGROUND

Although numerous studies have reported a decrease in dementia risk in the last two decades, it is unclear whether dementia-free cognitive function is also changing across generations.

OBJECTIVE

The objective was to systematically evaluate the published data on generational differences in cognitive function in the older population.

METHODS

Searches were performed on PubMed, Embase, and PsychInfo for articles published in English before 20 June 2021. Included studies were from population-based samples that reported generational differences in cognition in individuals without dementia, aged ≥60 years.

RESULTS

28,101 studies were identified and 15 selected covering the period from 1971 to 2015: including studies from China, Europe, and the USA. The results show generally consistent findings of improvements or stability in dementia free cognitive function in later versus earlier born generations, but not for all cognitive domains. Prevalence of mild cognitive impairment and cognitive impairment no dementia has remained stable in the USA, UK, and China over the last two decades.

RESULTS

Prevalence of vascular related mild cognitive impairment has increased in China. Improvements in cognition may only partially be explained by increased educational attainment across generations.

CONCLUSION

This review provides evidence for generational effects in dementia-free cognitive function, predominately stability or improvements in performance, in later compared to earlier born individuals across different world regions. There is an urgent need to determine the factors driving such changes and whether they are being experienced in all world regions, particularly low- and middle-income countries where the burden of cognitive impairment is greatest and rising.

Effects of Age, Level of Education and HIV Status on Cognitive Performance in West African Older Adults: The West Africa IeDEA Cohort Collaboration

An in-depth understanding of the impact of aging, cognitive reserve, and HIV status on cognitive function is needed in older West African adults. Ninety-nine HIV-negative and 334 HIV-positive adults aged ≥ 50 years were enrolled in three clinics (Senegal and Côte d'Ivoire) participating in the IeDEA West Africa collaboration. All subjects underwent the Free and Cued Selective Reminding Test (FCSRT) and the Isaacs Set Test (IST). Age (both linear and quadratic), education level, and HIV status effects on Z-scores were assessed using multivariate linear regression models. Interactions between HIV status and age or educational level were tested. In the present cohort of older West African adults, the role of age and educational level on episodic memory and verbal fluency was observed without revealing an interaction between HIV status and age effect. As age had quadratic effects, older HIV-positive adults should not be considered as a unique group irrespective of their age. Low-educated HIV-positive patients had the lowest verbal fluency performance compared to others. Further studies are needed to duplicate these results. In clinical settings, screening and adapted programs focusing on improving cognition in those patients are needed.

Patterns of Functional Impairment over Time Amongst Older Men-the Manitoba Follow-up Study

Background

To determine the incidence and prevalence patterns of activity of daily living (ADL) impairments in ageing men.

Methods

3,983 men were enrolled in the Manitoba Follow-up Study (MFUS) cohort study in 1948. From 1996 onwards, functional status was measured. We classified basic (BADL) and instrumental (IADL) into mutually exclusive categories as a time dependant factor after the second survey wave as: First survey response; no limitation; incident (first episode of disability); persistent (limitation which was seen on all questionnaires after the incident episode); resilient (noted in previous surveys but not present); and recurrent (noted in present survey, and limitations noted as present and absent in previous surveys).

Results

There were 1,745 participants in 1996 at a mean age of 76 years. Incident BADL limitations increased substantially with age: from 1% at age 75 to 15% at age 95. Similarly, persistent limitations increased with age: from 0.4% at age 75 to 18% at age 95. However, BADL function was fluid, with many individuals grouped within the resilient and recurrent patterns. Similar age effects and variability were noted in IADLs.

Conclusion

New and persistent disabilities are highly associated with age. However, there is considerable change in functional status over time.

Changes in Prefrontal Cortical Activity During Walking and Cognitive Functions Among Patients With Parkinson's Disease

Background: Walking becomes more and more degraded as Parkinson's Disease (PD) progresses. Previous research examined factors contributing to this deterioration. Among them, changes in brain cortical activity during walking have been less studied in this clinical population.

Objectives: This study aimed to: (1) investigate changes in dorsolateral prefrontal cortex (DLPFC) activation during usual walking and dual-task walking conditions in patients with PD; (2) examine the association between cortical activity and behavioral/cognitive outcomes; and (3) explore which factors best predict increased activation of the DLPFC during usual walking.

Methods: Eighteen patients with early stage PD and 18 controls performed 4 conditions: (1) standing while subtracting, (2) usual walking, (3) walking while counting forward, and (4) walking while subtracting. Cortical activity in DLPFC, assessed by changes in oxy-hemoglobin (ΔHbO₂) and deoxy-hemoglobin (ΔHbR), was measured using functional near infrared spectroscopy (fNIRS). Gait performance was recorded using wearables sensors. Cognition was also assessed using neuropsychological tests, including the Trail Making Test (TMT).

Results: DLPFC activity was higher in patients compared to controls during both usual walking and walking while subtracting conditions. Patients had impaired walking performance compared to controls only during walking while subtracting task. Moderate-to-strong correlations between ΔHbO₂ and coefficients of variation of all gait parameters were found for usual walking and during walking while counting forward conditions. Part-B of TMT predicted 21% of the variance of ΔHbO₂ during usual walking after adjustment for group status.

Conclusions: The increased DLPFC activity in patients during usual walking suggests a potential compensation for executive deficits. Understanding changes in DLPFC activity during walking may have implications for rehabilitation of gait in patients with PD.