The relation of the number of languages spoken to performance in different cognitive abilities in old age

Associations of multilingualism and language proficiency with cognitive functioning: epidemiological evidence from the SwissDEM study in community dwelling older adults and long-term care residents

BACKGROUND

We explored whether number of languages spoken and language proficiency are associated with cognitive performance among older adults living in the community and in long-term care (LTC) in Switzerland.

METHODS

Among study participants, 664 lived in the community in the Canton of Zurich (Mean age = 72.97 years; SD = 6.08), 386 lived in the community in Ticino (Mean age = 76.24 years; SD = 6.66), and 176 resided in LTC in Ticino (Mean age = 87.61 years; SD = 6.45). We recorded sociodemographic variables, number of languages spoken, language proficiency, and assessed overall cognitive performance, immediate and delayed memory, and verbal fluency with standardized tests. We used adjusted regression models.

RESULTS

A higher number of spoken languages was positively associated with overall cognitive performance, verbal fluency and immediate and delayed memory performance in community-dwelling older adults in the Cantons of Ticino and Zurich, (all p values ≤ 0.012;), but not in in older adults living in LTC homes (all p values ≥ 0.35). Higher language proficiency was associated with better memory performance among individuals living in the community in Ticino (p value = 0.003), and to better performance in verbal fluency and memory tasks in Zurich (p values ≤ 0.002). Among LTC residents, proficiency levels were not associated with cognitive performance.

CONCLUSIONS

Multilingualism and greater language proficiency were associated with better cognitive functioning in community-dwelling but not in institutionalized older adults. Multilingualism may contribute to cognitive reserve, as well as protect and delay cognitive decline in late life.

Interactional Effects Between Relational and Cognitive Reserves on Decline in Executive Functioning

OBJECTIVES

The present study set out to investigate associations of cognitive reserve (as indicated by education) and relational reserve (as indicated by the family network size and indices of emotional support) to decline in executive functioning over 6 years as measured by changes in Trail Making Test (TMT) completion time in older adults and whether education and network size interacted with age and sex as covariates with respect to this longitudinal association.

METHOD

We analyzed data from 897 participants tested on TMT parts A and B in two waves 6 years apart. The mean age in the first wave was 74.33 years. Participants reported information on their family networks and their level of education.

RESULTS

Latent change score modeling testing for moderation effects revealed a significant interaction of network size in the first wave of data assessment with education. Specifically, for lower levels of cognitive reserve (-1 SD of education), the longitudinal association between relational reserve in the first wave and subsequent changes in executive functioning was not significant. In contrast, for higher levels of cognitive reserve (+1 SD of education), a higher relational reserve in the first wave significantly predicted a smaller subsequent increase in TMT completion time from the first to the second wave (i.e., a smaller decline in executive functioning).

DISCUSSION

The present longitudinal study provides evidence for the interaction between cognitive and relational reserves. This confirms the hypothesis that reserves from different domains are intertwined and their combined effects contribute to less cognitive decline in old age.

Solving the Puzzle of Cognitive Reserve Effects on Cognitive Decline: The Importance of Considering Functional Impairment

AIMS

We investigated whether the longitudinal relation between cognitive reserve accumulated across the lifespan and rate of cognitive decline over 6 years differed by the individual's degree of functional impairment.

METHODS

We analyzed longitudinal data from 897 older adults (M = 74.33 years) tested on the Trail Making Test (TMT) in 2 waves 6 years apart.

RESULTS

There was a significant interaction of functional impairment with cognitive reserve on latent change in cognitive functioning. Specifically, with no functional impairment in the first wave of assessment, greater cognitive reserve accumulated across the lifespan significantly predicted a reduced cognitive decline over 6 years (i.e., smaller increase in TMT completion time). In contrast, with certain functional impairment (in at least some activities) in the first wave, greater cognitive reserve build-up predicted a steeper cognitive decline (i.e., larger increase in TMT completion time).

CONCLUSION

Individuals with greater cognitive reserve accumulated across the lifespan show a reduced cognitive decline if they still have relatively little functional impairment, while they will show a steeper decline (compared to individuals with less cognitive reserve) as soon as functional impairment becomes substantial.

Reserva cognitiva e os diferentes perfis de ganho cognitivo em idosos

O objetivo desse estudo foi verificar diferentes perfis de ganho cognitivo em idosos para a reserva cognitiva. Trata-se de uma scoping review, utilizando-se PubMed, Medline, Web of Science, Science Direct, Lilacs, SciELO, PsycInfo, PsycNet e AgeLine como base de dados; restringiu-se a busca entre o ano de 2008 e 2018. Identificou-se 2295 estudos e 51 foram elegíveis para a revisão. Dentre os 51 estudos selecionados, encontrou-se 9 perfis diferentes para manutenção cognitiva, sendo que 5 estudos não especificaram o perfil. Conclusão: Os perfis encontrados representaram relevância para a teoria de reserva cognitiva e forneceram esclarecimentos de como fatores individuais e de vida diária podem fazer o cérebro mais resiliente no envelhecimento e na velhice; no entanto, esses fatores individuais e o modo como eles contribuem para o desenvolvimento da reserva cognitiva e da manutenção da cognição ainda permanecem obscuras na literatura

Cognitive Reserve Moderates the Predictive Role of Memory Complaints for Subsequent Decline in Executive Functioning

Aims

We investigated whether the longitudinal relation between memory complaints and subsequent decline in executive functioning over 6 years differed by leisure activity engagement as major contributor to cognitive reserve in old age.

Methods

We analyzed longitudinal data from 897 older adults (M = 74.33 years) tested on the Trail Making Test (TMT) in two waves 6 years apart. Participants reported information on memory complaints and leisure activity engagement.

Results

There was a significant interaction of memory complaints with leisure activity engagement on latent change in executive functioning. Specifically, only for individuals with less (but not those with greater) leisure activity engagement, memory complaints significantly predicted a steeper subsequent decline in executive functioning across 6 years (i.e., increases in TMT completion time).

Conclusion

The role of memory complaints as an early predictor of decline in executive functioning seems to vary by individuals' cognitive reserve.

Exploring Language Learning as a Potential Tool against Cognitive Impairment in Late-Life Depression: Two Meta-Analyses and Suggestions for Future Research

Late-life depression (LLD) affects about an eighth of community-dwelling seniors. LLD impacts well-being, with loneliness and small social networks being typical. It has also been linked to cognitive dysfunction and an increased risk of developing dementia. Safety and efficacy of pharmacological treatments for LLD have been debated, and cognitive dysfunction often persists even after remission. Various cognitive interventions have been proposed for LLD. Among these, one has received special attention: foreign language learning could serve as a social intervention that simultaneously targets brain structures affected in LLD. Lifelong bilingualism may significantly delay the onset of cognitive impairment symptoms by boosting cognitive reserve. Even late-life foreign language learning without lifelong bilingualism can train cognitive flexibility. It is then counterintuitive that the effects of language learning on LLD have never been examined. In order to create a theoretical basis for further interdisciplinary research, this paper presents a status quo of current work through two meta-analyses investigating cognitive functioning in LLD on the one hand and in senior bilinguals or seniors following a language course on the other hand. While LLD was consistently associated with cognitive dysfunction, inconsistent results were found for bilingualism and language learners. Possible reasons for this and suggestions for future research are subsequently discussed.

Cognitive Reserve Attenuates 6-Year Decline in Executive Functioning after Stroke

AIMS

We investigated whether the longitudinal relationship between history of stroke and subsequent decline in executive functioning over 6 years differed by cognitive reserve.

METHODS

We analyzed longitudinal data from 897 older adults (mean age, 74.33 years) tested on the Trail Making Test (TMT) in two waves 6 years apart. Participants reported information on key frequently used proxies of lifelong cognitive reserve accumulation (i.e., education, occupation, and leisure activity engagement), and history of stroke.

RESULTS

There was a significant interaction of stroke with leisure activity engagement on latent change in executive functioning. Specifically, only for individuals with low (but not those with high) leisure activity engagement, history of stroke significantly predicted a steeper subsequent decline in executive functioning across 6 years (i.e., increases in TMT completion time).

CONCLUSION

The detrimental aftereffects of stroke on subsequent decline in executive functioning may be attenuated in individuals who have accumulated greater cognitive reserve through leisure activity engagement across their life.

Does bilingualism influence neuropsychological test performance in older adults? A systematic review

OBJECTIVE

Using standardized tests which have been normed on monolinguals for the assessment of bilinguals presents challenges to the accurate characterization of cognitive profile as the literature provides compelling evidence for the influence of bilingualism on cognitive abilities. However, little is known about the generalizability of these findings to clinical neuropsychology. The aim of this review was to address this gap by summarizing current evidence on the performance of bilingual older adults on standardized tests routinely used in clinical practice.

METHOD

A systematic search of Web of Science, PsycINFO and PubMed was conducted. 27 cross-sectional and longitudinal studies which use at least one standardized neuropsychological test for cognitive impairment were included in the review. Potential demographic (cultural/linguistic background of the participants, immigrant status), clinical (diagnostic status), and methodological confounders (language of test administration, components of bilingualism) were also examined. The review protocol was registered at the PROSPERO International Prospective Register of Systematic Review with registration number CRD42018114658.

RESULTS

The results of this review revealed some bilingual advantage on measures of inhibitory control and bilingual disadvantage on measures of verbal fluency in cross-sectional studies. Bilingualism status was not associated with test performance in longitudinal studies. However, findings lack consistency due to demographic variables and methodological differences across studies.

CONCLUSION

Neuropsychological tests assessing language domains and, to some extent executive function act as clinically relevant features of bilingualism for neuropsychological evaluation. However, immigration status, acculturation level and language of test administration needs to be taken into account when assessing bilingual older adults.

Cognitive Reserve Attenuates the Relation between Gastrointestinal Diseases and Subsequent Decline in Executive Functioning

AIMS

We investigated whether the longitudinal relationship between gastrointestinal diseases and subsequent decline in executive functioning over 6 years differed by cognitive reserve.

METHODS

We analyzed longitudinal data from 897 older adults (mean age 74.33 years) tested on TMT parts A and B in two waves 6 years apart. Participants reported information on education, occupation, leisure activity engagement, and gastrointestinal diseases.

RESULTS

There was a significant interaction of gastrointestinal diseases with leisure activity engagement on latent change in executive functioning. Specifically, only for individuals with low (but not those with high) leisure activity engagement, gastrointestinal diseases significantly predicted a steeper subsequent decline in executive functioning across 6 years (i.e., increases in TMT completion time).

CONCLUSION

Cognitive reserve may attenuate the detrimental influences of gastrointestinal diseases on subsequent decline in executive functioning.

Bilingualism Is Associated with a Delayed Onset of Dementia but Not with a Lower Risk of Developing it: a Systematic Review with Meta-Analyses

Some studies have linked bilingualism with a later onset of dementia, Alzheimer's disease (AD), and mild cognitive impairment (MCI). Not all studies have observed such relationships, however. Differences in study outcomes may be due to methodological limitations and the presence of confounding factors within studies such as immigration status and level of education. We conducted the first systematic review with meta-analysis combining cross-sectional studies to explore if bilingualism might delay symptom onset and diagnosis of dementia, AD, and MCI. Primary outcomes included the age of symptom onset, the age at diagnosis of MCI or dementia, and the risk of developing MCI or dementia. A secondary outcome included the degree of disease severity at dementia diagnosis. There was no difference in the age of MCI diagnosis between monolinguals and bilinguals [mean difference: 3.2; 95% confidence intervals (CI): -3.4, 9.7]. Bilinguals vs. monolinguals reported experiencing AD symptoms 4.7 years (95% CI: 3.3, 6.1) later. Bilinguals vs. monolinguals were diagnosed with dementia 3.3 years (95% CI: 1.7, 4.9) later. Here, 95% prediction intervals showed a large dispersion of effect sizes (-1.9 to 8.5). We investigated this dispersion with a subgroup meta-analysis comparing studies that had recruited participants with dementia to studies that had recruited participants with AD on the age of dementia and AD diagnosis between mono- and bilinguals. Results showed that bilinguals vs. monolinguals were 1.9 years (95% CI: -0.9, 4.7) and 4.2 (95% CI: 2.0, 6.4) older than monolinguals at the time of dementia and AD diagnosis, respectively. The mean difference between the two subgroups was not significant. There was no significant risk reduction (odds ratio: 0.89; 95% CI: 0.68-1.16) in developing dementia among bilinguals vs. monolinguals. Also, there was no significant difference (Hedges' g = 0.05; 95% CI: -0.13, 0.24) in disease severity at dementia diagnosis between bilinguals and monolinguals, despite bilinguals being significantly older. The majority of studies had adjusted for level of education suggesting that education might not have played a role in the observed delay in dementia among bilinguals vs. monolinguals. Although findings indicated that bilingualism was on average related to a delayed onset of dementia, the magnitude of this relationship varied across different settings. This variation may be due to unexplained heterogeneity and different sources of bias in the included studies. Registration: PROSPERO CRD42015019100.

The Bidirectional in Bilingual: Cognitive, Social and Linguistic Effects of and on Third-Age Language Learning

Bilingualism has been put forward as a life experience that, similar to musical training or being physically active, may boost cognitive performance and slow down age-related cognitive decline. In more recent years, bilingualism has come to be acknowledged not as a trait but as a highly individual experience where the context of use strongly modulates any cognitive effect that ensues from it (cf. van den Noort et al., 2019). In addition, modulating factors have been shown to interact in intricate ways (Pot, Keijzer and de Bot, 2018). Adding to the complexity is the fact that control processes linked to bilingualism are bidirectional-just as language control can influence cognitive control, individual differences in cognitive functioning often predict language learning outcomes and control. Indeed, Hartsuiker (2015) posited the need for a better understanding of cognitive control, language control as well as the transfer process between them. In this paper, we aim to shed light on the bidirectional and individual cognitive, social and linguistic factors in relation to bilingualism and second language learning, with a special focus on older adulthood: (1) we first show the intricate clustering of modulating individual factors as deterministic of cognitive outcomes of bilingual experiences at the older end of the lifespan; (2) we then present a meta-study of work in the emergent field of third-age language learning, the results of which are related to lifelong bilingualism; (3) objectives (1) and (2) are then combined to result in a blueprint for future work relating cognitive and social individual differences to bilingual linguistic outcomes and vice versa in the context of third-age language learning.

Sequential Multilingualism and Cognitive Abilities: Preliminary Data on the Contribution of Language Proficiency and Use in Different Modalities

This exploratory study focuses on sequential bi-/multilinguals (specifically, nonimmigrant young Dutch native speakers who learned at least one foreign language (FL) at or after the age of 5) and investigates the impact of proficiency-based and amount-of-use-based degrees of multilingualism in different modalities (i.e., speaking, listening, writing, reading) on inhibition, disengagement of attention, and switching. Fifty-four participants completed a comprehensive background questionnaire, a nonverbal fluid intelligence task, a Flanker task, and the Trail Making Test. Correlational and regression analyses considering multilingualism related variables and other variables that may contribute to the cognitive abilities under investigation (e.g., years of formal education, socioeconomic status, physical activity, playing video-games) revealed that only proficiency-based degrees of multilingualism impacted cognitive abilities. Particularly, mean FL writing proficiency affected inhibition (i.e., significant positive flanker effect) and L2 listening proficiency influenced disengagement of attention (i.e., significant negative sequential congruency effect). Our findings suggest that only those speakers who have reached a certain proficiency threshold in more than one FL show a cognitive advantage, which, in our sample, emerged in inhibition only. Furthermore, our study suggests that, regarding the impact of proficiency-based degrees of multilingualism on cognitive abilities, for our participants the writing and listening modalities mattered most.

A Systematic Review on the Possible Relationship Between Bilingualism, Cognitive Decline, and the Onset of Dementia

A systematic review was conducted to investigate whether bilingualism has a protective effect against cognitive decline in aging and can protect against dementia. We searched the Medline, ScienceDirect, Scopus, and ERIC databases with a cut-off date of 31 March, 2019, thereby following the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) protocol. Our search resulted in 34 eligible studies. Mixed results were found with respect to the protective effect of bilingualism against cognitive decline. Several studies showed a protective effect whereas other studies failed to find it. Moreover, evidence for a delay of the onset of dementia of between 4 and 5.5 years in bilingual individuals compared to monolinguals was found in several studies, but not in all. Methodological differences in the set-up of the studies seem to explain these mixed results. Lifelong bilingualism is a complex individual process, and many factors seem to influence this and need to be further investigated. This can be best achieved through large longitudinal studies with objective behavioral and neuroimaging measurements. In conclusion, although some evidence was found for a cognitive reserve-enhancing effect of lifelong bilingualism and protection against dementia, to date, no firm conclusions can be drawn.

Cognitive Reserve and Social Capital Accrued in Early and Midlife Moderate the Relation of Psychological Stress to Cognitive Performance in Old Age

AIMS

The present study set out to investigate the relation of psychological stress to cognitive performance and its interplay with key life course markers of cognitive reserve and social capital in a large sample of older adults.

METHODS

We assessed cognitive performance (verbal abilities and processing speed) and psychological stress in 2,812 older adults. The Participants reported information on education, occupation, leisure activities, family, and close friends.

RESULTS

Greater psychological stress was significantly related to lower performance in verbal abilities and processing speed. Moderation analyses suggested that the relations of psychological stress to cognitive performance were reduced in individuals with higher education, a higher cognitive level of the first profession practiced after education, a larger number of midlife leisure activities, a larger number of significant family members, and a larger number of close friends.

CONCLUSION

Cognitive reserve and social capital accrued in early and midlife may reduce the detrimental influences of psychological stress on cognitive functioning in old age.

High-Density Lipoprotein Cholesterol Level Relates to Working Memory, Immediate and Delayed Cued Recall in Brazilian Older Adults: The Role of Cognitive Reserve

AIMS

The present study set out to investigate the relation of the high-density lipoprotein cholesterol (HDL-C) level to cognitive performance and its interplay with key markers of cognitive reserve in a large sample of older adults.

METHODS

We assessed tests of working memory, immediate and delayed cued recall in 701 older adults from Amazonas, Brazil. The HDL-C level was derived from fasting blood samples. In addition, we interviewed individuals on their education, past occupation, and cognitive leisure activity.

RESULTS

A critically low HDL-C level (<40 mg/dL) was significantly related to lower performance in working memory, immediate and delayed cued recall. Moderation analyses suggested that the relations of the HDL-C level to working memory and delayed cued recall were negligible in individuals with longer education, a higher cognitive level of the job, and greater engagement in cognitive leisure activity.

CONCLUSION

Cognitive reserve accumulated during the life course may reduce the detrimental influences of a critically low HDL-C level on cognitive functioning in old age.

Intensity of Multilingual Language Use Predicts Cognitive Performance in Some Multilingual Older Adults

Cognitive advantages for bilinguals have inconsistently been observed in different populations, with different operationalisations of bilingualism, cognitive performance, and the process by which language control transfers to cognitive control. This calls for studies investigating which aspects of multilingualism drive a cognitive advantage, in which populations and under which conditions. This study reports on two cognitive tasks coupled with an extensive background questionnaire on health, wellbeing, personality, language knowledge and language use, administered to 387 older adults in the northern Netherlands, a small but highly multilingual area. Using linear mixed effects regression modeling, we find that when different languages are used frequently in different contexts, enhanced attentional control is observed. Subsequently, a PLS regression model targeting also other influential factors yielded a two-component solution whereby only more sensitive measures of language proficiency and language usage in different social contexts were predictive of cognitive performance above and beyond the contribution of age, gender, income and education. We discuss these findings in light of previous studies that try to uncover more about the nature of bilingualism and the cognitive processes that may drive an advantage. With an unusually large sample size our study advocates for a move away from dichotomous, knowledge-based operationalisations of multilingualism and offers new insights for future studies at the individual level.