Both odor identification and ApoE-ε4 contribute to normative cognitive aging

Research indicates that apoliprotein E (ApoE) plays a role in the development of Alzheimer's disease (AD) and possibly in the cognitive decline associated with normative aging. More recently, researchers have shown that ApoE is expressed in olfactory brain structures, and a relationship among ApoE, AD, and olfactory function has been proposed. In the current analyses, we investigated the contribution of ApoE and odor identification in decline trajectories associated with normative cognitive aging in various domains, using longitudinal data on cognitive performance available from the Swedish Adoption/Twin Study of Aging. Data on both ApoE status and olfactory functioning were available from 455 individuals ranging in age from 50 to 88 years at the first measurement occasion. Odor identification was measured via a mailed survey. Cognitive performance was assessed in up to 5 waves of in-person testing covering a period of 16 years. Latent growth curve analyses incorporating odor identification and ApoE status indicated a main effect of odor identification on the performance level in three cognitive domains: verbal, memory, and speed. A main effect of ApoE on rates of decline after age 65 was found for verbal, spatial, and speed factors. The consistency of results across cognitive domains provides support for theories that posit central nervous system-wide origins of the olfaction-cognition-ApoE relationship; however, olfactory errors and APOE ε4 show unique and differential effects on cognitive trajectory features.     

Dopamine and cognitive functioning: brain imaging findings in Huntington's disease and normal aging

Recent brain imaging studies in Huntington's disease (HD) and normal aging suggest a relationship between central dopaminergic neurotransmission and cognitive performance. Results demonstrate substantial losses in dopamine (DA) function in both HD and aging. Moreover, HD patients and older adults show deficits across multiple cognitive domains, including episodic memory, speed of processing, and executive functioning. Although few studies are available at present, there is converging evidence that multiple measures of pre- and postsynaptic DA biochemistry are (a) highly interrelated, and (b) strongly associated with the cognitive deficits that accompany HD and aging. There is also emerging evidence that DA neurotransmission influences cognitive performance independent of HD or age. In general, the research reviewed in this article indicates that the nigrostriatal DA system is an important component of a frontostriatal circuitry that is critically involved in cognitive functioning.     

Cognitive Functioning in Aging and Dementia: The Kungsholmen Project

The Kungsholmen Project (KP) is a community-based longitudinal study of aging and dementia targeting the 75+ population. In this article, we review empirical studies with a cognitive focus from the KP. The main findings indicate that (a) there is an age-related decline for some cognitive domains (e.g., episodic memory, verbal fluency, visuoconstructive skill, psychomotor speed), but not for others (e.g., primary memory, visuoperceptive skill, motor-hand coordination), (b) multiple individual-difference variables within demographic (e.g., sex, education) life-style (e.g., activity levels), genetic (e.g., apolipoprotein E genotype), and health-related (e.g., vitamin B deficiency, depression, diabetes) domains are related to late-life cognitive functioning, (c) a potential for improving cognitive performance – a reserve capacity – is present also among very old adults, (d) the 2 most common dementia diseases, Alzheimer’s disease (AD) and vascular dementia (VaD), affect cognition in a strikingly similar manner, (e) the role of individual-difference variables in cognitive functioning is markedly reduced in dementia – the pathogenesis itself may overshadow the influence of other variables, and (f) there is a long preclinical period in dementia during which cognitive deficits are detectable. As is true with the other projects represented in this issue, the KP portrays a rather diversified picture of cognitive aging, although systematic patterns are evident with regard to the variability of late-life cognitive functioning.     

The relationship between cognitive performance and electrophysiological indices of performance monitoring

Studies of electrophysiological indices of performance monitoring, such as the error-related negativity (ERN), posterror positivity (Pe), and N2 components of the event-related potential (ERP), suggest that increased ERN and Pe amplitudes and decreased N2 amplitudes are associated with better cognitive flexibility and cognitive control abilities; however, few studies have directly examined the relationship between cognitive performance and ERP indices of performance monitoring. We examined the neuropsychological profile of 89 healthy individuals who performed a modified flanker task. The neuropsychological domains tested included memory, verbal fluency, and attention/executive functioning. Pearson’s correlations and multiple regression analyses showed a significant relationship between measures of attention/executive functioning and ERN amplitude, even when negative affect, reaction time interference, and posterror slowing were controlled. N2 amplitude related only to posterror slowing. The amplitude of the Pe was not significantly related to any cognitive domains. These findings are consistent with recent work indicating that performance monitoring requires attention skills and cognitive flexibility. Implications for the conflict-monitoring and reinforcement-learning theories are discussed.     

A meta-analysis of the effects of antidepressants on cognitive functioning in depressed and non-depressed samples

A thorough understanding of the cognitive effects of antidepressant medications is essential given their frequency of use. This meta-analysis was conducted to investigate whether antidepressants differentially affect the various domains of cognitive functioning for depressed and non-depressed participants. An electronic search of PsycInfo, Medline and Google Scholar was conducted for all journal articles published between January 1998 and January 2017. Thirty-three studies were included enabling calculation of Hedges’ g using a random effects model for the cognitive domains of divided attention, executive function, expressive language, immediate memory, perceptual motor skills, processing speed, recent memory, sustained attention, visuospatial-constructional skills and working memory. Results revealed that overall, antidepressants have a modest, positive effect on divided attention, executive function, immediate memory, processing speed, recent memory and sustained attention for depressed participants. Selective serotonin reuptake inhibitors (SSRI’s) were found to have the greatest positive effect on cognition for depressed participants, as compared to the other classes of antidepressants analysed. Antidepressants did not significantly affect cognitive function in non-depressed participants.     

An analysis of diversity in the cognitive performance of elderly community dwellers: individual differences in change scores as a function of age.

This longitudinal study investigated whether age is associated with increases in interindividual variability across 4 ability domains using a sample of 426 elderly community dwellers followed over 3.5 years. Interindividual variability in change scores increased with age for memory, spatial functioning, and speed but not for crystallized intelligence for the full sample and in a subsample that excluded dementia or probable dementia cases. Hierarchical regression analyses indicated that being female, having weaker muscle strength, and having greater symptoms of illness and greater depression were associated with overall greater variability in cognitive scores. Having a higher level of education was associated with reduced variability. These findings are consistent with the view that there is a greater range of responses at older ages, that certain domains of intelligence are less susceptible to variation than others and that variables other than age affect cognitive performance in later life.     

Genetic Mediation of the Associations Among Motor and Perceptual Speed and Adult Cognitive Abilities

Quantitative genetic analyses were conducted to determine the genetic mediation of the associations among motor speed, perceptual speed, and cognitive abilities in normal aging. Measures of motor performance, perceptual speed, and cognitive functioning in four domains (crystallized, fluid, spatial, and memory) were available from the Swedish Adoption/Twin Study of Aging. The sample included 206 twin pairs ranging in age from 44 to 82 years. A Motor Speed factor was constructed from 17 timed measures of motor performance. Heritability of Motor Speed was .26 in middle-aged twins and .00 in older twins. Results indicated that genetic variance in cognitive functioning in the middle-aged cohort may be defined by working memory, whereas genetic variance in the older cohort was defined by perceptual speed. Indications of a nonshared environmental component in the association among motor speed, perceptual speed, and spatial abilities suggest possible frontal lobe involvement.     

Fonctions exécutives,vieillissement cognitif et variations stratégiques

Aging is characterized by a decrease of cognitive performance in most of cognitive domains. One of the most fundamental issues is then to know what are the underlying mechanisms of these age-related changes in human cognition. Recent research suggests that in addition to speed of processing and working memory capacities, age-related impairment in executive functioning plays an important role in the cognitive decline associated to aging. Above and beyond performance, current research shows that the mediating role of executive function in age-related changes in cognitive performance occurs via changes in strategies variations (i.e., repertoire, distribution, execution, and selection of the strategies used to accomplish a cognitive task). In this article, we illustrate both strategic variations and underlying executive control mechanisms in two important cognitive domains : episodic memory and problem solving.     

The relation between APOE status and neuropsychological memory test performance: an analysis of the Canadian Study of Health and Aging

This study examined the relationship between two risk factors for dementia, the apolipoprotein (APOE) epsilon4 allele and poor memory test performance. Participants were from the Canadian Study of Health and Aging, a 4-year longitudinal population-based study. Persons with no cognitive impairment who had an epsilon4 allele but whose memory was average or better were not at increased risk of developing dementia after five years. Risk was increased for those with below average memory and no epsilon4 allele, but was particularly increased for those with below average memory and an epsilon4 allele. While the APOE epsilon4 allele was associated with slightly lower memory test performance for persons without cognitive impairment at baseline, it only increased their risk of developing dementia if their memory was below average.     

Mindfulness induction and cognition: A systematic review and meta-analysis

Mindfulness meditation might improve a variety of cognitive processes, but the available evidence remains fragmented. This preregistered meta-analysis (PROSPERO-CRD42018100320) aimed to provide insight into this hypothesis by assessing the effects of brief mindful attention induction on cognition. Articles were retrieved from Pubmed, PsycInfo and Web of Science up until August 1, 2018. A total of 34 studies were included. The outcomes were categorized into four cognitive domains: attentional functioning, memory, executive functioning and higher-order function. A small effect was found across all cognitive domains (Hedges’ g = 0.18, 95% IC = 0.07–0.29). Separated analyses for each cognitive domain revealed an effect only in higher-order cognitive functions (k = 10, Hedges’ g = 0.35, 95% IC = 0.20–0.50). Results suggest that mindfulness induction improves cognitive performance in tasks involving complex higher-order functions. There was no evidence of publication bias, but studies generally presented many methodological flaws.     

Does Therapeutic Repetitive Transcranial Magnetic Stimulation Cause Cognitive Enhancing Effects in Patients with Neuropsychiatric Conditions? A Systematic Review and Meta-Analysis of Randomised Controlled Trials

Repetitive transcranial magnetic stimulation (rTMS) is increasingly used as a therapeutic intervention for neuropsychiatric illnesses and has demonstrated efficacy for treatment of major depression. However, an unresolved question is whether a course of rTMS treatment results in effects on cognitive functioning. In this systematic review and meta-analysis we aimed to quantitatively determine whether a course of rTMS has cognitive enhancing effects. We examined cognitive outcomes from randomised, sham-controlled studies conducted in patients with neuropsychiatric conditions where rTMS was administered to the dorsolateral prefrontal cortex (DLPFC) across repeated sessions, searched from PubMed/MEDLINE and other databases up until October 2015. Thirty studies met our inclusion criteria. Cognitive outcomes were pooled and examined across the following domains: Global cognitive function, executive function, attention, working memory, processing speed, visual memory, verbal memory and visuospatial ability. Active rTMS treatment was unassociated with generalised gains across the majority of domains of cognitive functioning examined. Secondary analyses revealed a moderate sized positive effect for improved working memory in a small number of studies in patients with schizophrenia (k = 3, g = 0.507, 95 % CI = [0.183–0.831], p < .01). Therapeutic rTMS when administered to the DLPFC in patients with neuropsychiatric conditions does not result in robust cognitive enhancing effects.     

Cognitive and non-cognitive factors contributing to the longitudinal identification of successful older adults in the betula study

Studies of successful aging have typically defined elderly who fall in the upper end of a distribution of test scores as successful. A different definition of successful aging requires that older adults fall at or above the mean level of younger adults and maintain this level over time. Here we examined this definition of successful aging in a sample of 1463 individuals between the ages of 50 of 85. Based on principal coordinate analysis of cognitive and non-cognitive variables, we identified a group of 55 (8.3%) 70-85 years olds that were high functioning. This group of elderly showed elevated performance on a range of cognitive tasks. Non-cognitive factors that characterized this group included education and subjective health. The participants were retested 5 years later and the same type of analysis was repeated. Of the remaining individuals who initially were classified as high functioning, 18 (35%) remained high functioning and thus met the definition for successful aging. Years of education was a significant predictor of who remained successful over time.     

Cognitive aging and flight performances in general aviation pilots

Unlike professional pilots who are limited by the FAA's age rule, no age limit is defined in general aviation. Our overall goal was to examine how age-related cognitive decline impacts piloting performance and weather-related decision-making. This study relied on three components: cognitive assessment (in particular executive functioning), pilot characteristics (age and flight experience), and flight performance. The results suggest that in comparison to chronological age, cognitive assessment is a better criterion to predict the flight performance, in particular because of the inter-individual variability of aging impact on cognitive abilities and the beneficial effect of flight experience.     

Cerebral White Matter Integrity and Cognitive Aging: Contributions from Diffusion Tensor Imaging

The integrity of cerebral white matter is critical for efficient cognitive functioning, but little is known regarding the role of white matter integrity in age-related differences in cognition. Diffusion tensor imaging (DTI) measures the directional displacement of molecular water and as a result can characterize the properties of white matter that combine to restrict diffusivity in a spatially coherent manner. This review considers DTI studies of aging and their implications for understanding adult age differences in cognitive performance. Decline in white matter integrity contributes to a disconnection among distributed neural systems, with a consistent effect on perceptual speed and executive functioning. The relation between white matter integrity and cognition varies across brain regions, with some evidence suggesting that age-related effects exhibit an anterior–posterior gradient. With continued improvements in spatial resolution and integration with functional brain imaging, DTI holds considerable promise, both for theories of cognitive aging and for translational application.     

Decomposing the relationship between cognitive functioning and self-referent memory beliefs in older adulthood: what’s memory got to do with it?

With advancing age, episodic memory performance shows marked declines along with concurrent reports of lower subjective memory beliefs. Given that normative age-related declines in episodic memory co-occur with declines in other cognitive domains, we examined the relationship between memory beliefs and multiple domains of cognitive functioning. Confirmatory bi-factor structural equation models were used to parse the shared and independent variance among factors representing episodic memory, psychomotor speed, and executive reasoning in one large cohort study (Senior Odyssey, N = 462), and replicated using another large cohort of healthy older adults (ACTIVE, N = 2802). Accounting for a general fluid cognitive functioning factor (comprised of the shared variance among measures of episodic memory, speed, and reasoning) attenuated the relationship between objective memory performance and subjective memory beliefs in both samples. Moreover, the general cognitive functioning factor was the strongest predictor of memory beliefs in both samples. These findings are consistent with the notion that dispositional memory beliefs may reflect perceptions of cognition more broadly. This may be one reason why memory beliefs have broad predictive validity for interventions that target fluid cognitive ability.     

Liens entre le déclin sensoriel et cognitif dans le vieillissement normal : revue critique de la littérature et apports de l’approche incarnée et située de la cognition

Biological aging impacts many organs including sensory's ones and the brain, and thus, cognition. Research has shown that the sensory and cognitive decline are positively correlated. The main data from this literature are firstly reviewed in the present article. Then, the four main hypotheses that are generally proposed to explain these associations are presented. According to them, sensory decline is supposed to cause cognitive decline, or vice-versa, or these concomitant changes result from the general alteration of the nervous system. However, none of them seems able to account for all of the existing data. Moreover, the precise mechanisms that may drive these associations remain to be clarified. The rest of the article is then dedicated to the embodied and situated cognition approach as it provides a particularly interesting and adequate framework to account for these links. Indeed, according to this approach, cognitive representations are grounded in their sensorimotor properties. In other words, cognitive functioning is not conceived as detached from sensory functioning, but instead directly dependent of it. Representations are thus thought to emerge from the sensorimotor simulation of the properties involved in these representations. Therefore, sensory decline should directly impact cognitive performance. It is then hypothesized that older adults have low-resolution representations decreasing the signal on noise ratio of traces, increasing sensorimotor interferences and thus decreasing cognitive performance. This approach leads to consider low and high levels of sensory and perceptual functioning, which are both impaired in aging. Therefore, the repercussion of the sensory-perceptual decline is not only valid for present processing, but also extend to all past knowledge. Several predictions are then proposed on (1) the link between high-level perceptual functioning and cognitive functioning in older adults; (2) the possible interaction in young adults between sensory and high-level perceptual functioning as a function of the level of interference of the material involved; (3) the possible link between the motor and cognitive functioning in older adults. The clinical consequences in terms of cognitive stimulation of such a perspective will close the article. It is proposed to develop a stimulation program based on pattern separation mechanism to better process sensory interference in order to train older adults to improve cognitive precision and thus performance.     

Terminal decline and cognitive performance in very old age: does cause of death matter?

Cross-sectional differences and longitudinal changes in cognitive functioning in relation to mortality across a 7-year follow-up period, with 3 times of measurement, were examined in a population-based sample of very old adults. The authors also sought to determine whether cause of death (cerebro/cardiovascular disease [CVD]; non-CVD) modified the magnitude of mortality-related cognitive deficits. Cognitive performance was indexed by tests of general cognitive ability, episodic memory, primary memory, verbal fluency, and visuospatial ability. Results indicated cross-sectional differences on all domains of functioning, with persons who would die within 3 years after baseline testing performing more poorly. Longitudinally, greater decrements were observed on all domains for persons who would die after the first follow-up period, as compared with survivors. Cause of death failed to modify the magnitude of the cross-sectional and longitudinal deficits. The pattern of results point to the general nature of this phenomenon.     

Cognitive and Non-Cognitive Factors Contributing to the Longitudinal Identification of Successful Older Adults in the Betula Study

ABSTRACT

Studies of successful aging have typically defined elderly who fall in the upper end of a distribution of test scores as successful. A different definition of successful aging requires that older adults fall at or above the mean level of younger adults and maintain this level over time. Here we examined this definition of successful aging in a sample of 1463 individuals between the ages of 50 of 85. Based on principal coordinate analysis of cognitive and non-cognitive variables, we identified a group of 55 (8.3%) 70–85 years olds that were high functioning. This group of elderly showed elevated performance on a range of cognitive tasks. Non-cognitive factors that characterized this group included education and subjective health. The participants were retested 5 years later and the same type of analysis was repeated. Of the remaining individuals who initially were classified as high functioning, 18 (35%) remained high functioning and thus met the definition for successful aging. Years of education was a significant predictor of who remained successful over time.     

Behavioral dysexecutive symptoms in normal aging

Executive deficits of normal aging such as deficits in planning, organization or decision making are likely to affect elderly individuals in their daily life functioning. Therefore, executive functioning in aging seems to be interesting to study not only in cognitive terms but also in relation to the behavioral area. This pilot study aimed to investigate the nature of behavioral dysexecutive problems in a sample of normal elderly adults as measured by the Dysexecutive Questionnaire. Factor analysis showed that five interpretable factors could be derived from the DEX: intentionality (factor 1), interference management (factor 2), inhibition (factor 3), planning (factor 4), and social regulation (factor 5), suggesting that different components may underlie the behavioral dysexecutive symptoms of normal aging. The relationship between these factors and neuropsychological measures of Executive Functions were also briefly explored.     

Performance variability is related to change in cognition: evidence from the Victoria Longitudinal Study

Performance variability across repeated task administrations may be an important indicator of age-related cognitive functioning. In the present investigation, the authors examined whether age differences and change in inconsistency were related to 6-year (3 occasion) cognitive change. Inconsistency scores were computed from 4 reaction time tasks performed by 446 older adults (54-89 years). Replicating previous cross-sectional results, greater inconsistency was observed for older participants even after controlling for differences in response speed. New longitudinal results demonstrated (a) associations between inconsistency at baseline measurement and 6-year change in cognitive performance; (b) longitudinal change in inconsistency; and (c) intraindividual covariation between 6-year change in inconsistency and 6-year change in level of cognitive function. These findings support the view that performance variability serves as a marker of cognitive aging.