Intact reversed language-dominance but exaggerated cognate effects in reading aloud of language switches in bilingual Alzheimer's disease

Language switching and speaking a nondominant language challenge executive control: Preliminary data for novel behavioral markers of Alzheimer's risk in Spanish-English bilinguals

OBJECTIVE

The present study explored psycholinguistic analysis of spoken responses produced in a structured interview and cued linguistic and nonlinguistic task switching as possible novel markers of Alzheimer's disease (AD) risk in Spanish-English bilinguals.

METHOD

Nineteen Spanish-English bilinguals completed an Oral Proficiency Interview (OPI) in both languages, cued-switching tasks, and a battery of traditional neuropsychological tests (in a separate testing session). All were cognitively healthy at the time of testing, but eight decliners were later diagnosed with AD (on average 4.5 years after testing; SD = 2.3), while 11 controls remained cognitively healthy.

RESULTS

Past studies showed picture naming was more sensitive to AD in the dominant than in the nondominant language, but we found the opposite for a composite measure of spoken utterances produced in the OPI that included revisions, repetitions, and filled pauses (RRFPs), which were especially sensitive to AD risk in the nondominant language. Errors produced on language switch trials best discriminated decliners from controls (in receiver operating characteristic curves), and though the nonlinguistic switching task was also sensitive to AD risk, it elicited more errors overall and was also negatively affected by increased age and low education level.

CONCLUSIONS

Speaking a nondominant language and errors in cued language switching provided sensitive and specific markers of pending cognitive decline and AD risk in bilinguals. These measures may reflect early decline in executive control abilities that are needed to plan and monitor the production of connected speech and to manage competition for selection between languages. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Autocorrection if→of function words in reading aloud: A novel marker of Alzheimer's risk

OBJECTIVE

The present study investigated cognitive mechanisms underlying the ability to stop "autocorrect" errors elicited by unexpected words in a read-aloud task, and the utility of autocorrection for predicting Alzheimer's disease (AD) biomarkers.

METHOD

Cognitively normal participants (total n = 85; n = 64 with cerebrospinal fluid [CSF] biomarkers) read aloud six short paragraphs in which 10 critical target words were replaced with autocorrect targets, for example, The player who scored that final [paint] for the local team reported [him] experience. Autocorrect targets either replaced the most expected/dominant completion (i.e., point) or a less expected/nondominant completion (i.e., basket), and within each paragraph half of the autocorrect targets were content words (e.g., point/paint) and half were function words (e.g., his/him). Participants were instructed to avoid autocorrecting.

RESULTS

Participants produced more autocorrect errors in paragraphs with dominant than with nondominant targets, and with function than with content targets. Cognitively normal participants with high CSF Tau/Aβ42 (i.e., an AD-like biomarker profile) produced more autocorrect total errors than those below the Tau/Aβ42 threshold, an effect also significant with dominant-function targets alone (e.g., saying his instead of him). A logistic regression model with dominant-function errors and age showed errors as the stronger predictor of biomarker status (sensitivity 83%; specificity 85%).

CONCLUSIONS

Difficulty stopping autocorrect errors is associated with biomarkers indicating preclinical AD, and reveals promise as a diagnostic tool. Greater vulnerability of function over content words to autocorrection in individuals with AD-like biomarkers implicates monitoring and attention (rather than semantic processing) in the earliest of cognitive changes associated with AD risk. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Which language is more affected in bilinguals with Alzheimer's disease? Diagnostic sensitivity of the Multilingual Naming Test

OBJECTIVE

This study examined the joint consequences of bilingualism and Alzheimer's disease (AD) for picture naming ability to determine which language is more affected by AD and what scoring methods best distinguish patients from controls.

METHOD

Sixty-five Spanish-English bilinguals including 26 with dementia and 39 controls with equivalent age, education, and bilingual proficiency level, were tested on the Multilingual Naming Test (Gollan et al., 2012).

RESULTS

Bilinguals with AD named fewer pictures than controls, and overall AD seemed to affect both languages about equally, but exploratory analyses suggested that this varied with item difficulty. In the dominant language difficult items exhibited a larger effect of AD than easy items (which were at ceiling for both patients and controls), whereas in the nondominant language items of all difficulty levels were about equally affected by AD. An "either-language" scoring procedure (that counted items as correct if produced only in one of the two languages) increased naming scores especially in balanced bilinguals, and to an equal extent in patients and controls. Receiver Operating Characteristic analyses revealed that dominant language and either-language naming scores classified bilinguals as patients versus controls equally well and adding nondominant language scores did not improve diagnostic sensitivity.

CONCLUSIONS

Testing primarily or exclusively in the dominant language is best for detecting AD naming impairments in bilinguals. However, AD affects the ability to access names in both languages, possibly for different reasons, and simple descriptions of language decline as "parallel" or "asymmetrical" (i.e., AD affecting one language more than the other) may be misleading in terms of the theoretical implications for bilingual language processing. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Inhibitory control of the dominant language: Reversed language dominance is the tip of the iceberg

Theories of speech production have proposed that in contexts where multiple languages are produced, bilinguals inhibit the dominant language with the goal of making both languages equally accessible. This process often overshoots this goal, leading to a surprising pattern: better performance in the nondominant vs. dominant language, or reversed language dominance effects. However, the reliability of this effect in single word production studies with cued language switches has been challenged by a recent meta-analysis. Correcting for errors in this analysis, we find that dominance effects are reliably reduced and reversed during language mixing. Reversed dominance has also consistently been reported in the production of connected speech elicited by reading aloud of mixed language paragraphs. When switching, bilinguals produced translation-equivalent intrusion errors (e.g., saying pero instead of but) more often when intending to produce words in the dominant language. We show this dominant language vulnerability is not exclusive to switching out of the nondominant language and extends to non-switch words, linking connected speech results to patterns first reported in single word studies. Reversed language dominance is a robust phenomenon that reflects the tip of the iceberg of inhibitory control of the dominant language in bilingual language production.

Intestinal Flora Balance Therapy Based on Probiotic Support Improves Cognitive Function and Symptoms in Patients with Alzheimer's Disease: A Systematic Review and Meta-analysis

Objective

The clinical value of intestinal flora balance therapy based on probiotic support in improving cognitive function and symptoms of patients with Alzheimer's disease was to systematically evaluate, so as to provide evidence-based medicine basis for the promotion and use of this therapy.

Methods

The randomized controlled trials (RCTs) were searched for the improvement of cognitive function and symptoms of patients with Alzheimer's disease by intestinal flora balance therapy supported mainly by probiotics in PubMed, EMBASE, ScienceDirect, Cochrane Library, China Knowledge Network Database (CNKI), China VIP database, Wanfang database, and China Biomedical Literature Database (CBM) online database (RCT). Data were extracted independently by two researchers, and the literature was assessed for risk of bias according to the Cochrane Handbook 5.1.0 criteria. The data were meta-analyzed using RevMan 5.4 statistical software.

Results

Finally, 5 randomized controlled trials were included, with a total sample size of 386 cases. The results of meta-analysis showed that Chi2 = 13.14, df = 2, P = 0.001, and I 2 = 85% showed significant heterogeneity in the inclusion of the study data. Probiotic-supported intestinal microflora balance therapy improves cognitive function in patients with Alzheimer's disease. Through meta-analysis of transient memory scores, it is concluded that intestinal flora balance therapy based on probiotic support can improve transient memory in patients with Alzheimer's disease. Meta-analysis of ADAS-COG score showed that intestinal flora balance therapy supported by probiotics could improve the cognitive function of patients with Alzheimer's disease. The ADL score was analyzed by meta, and the heterogeneity test result was Chi2 = 0.79, df = 1, P = 0.37 > 0.05, and I 2 = 0%, indicating that the intestinal flora balance therapy supported by probiotics can improve the ability of daily living of patients with Alzheimer's disease.

Conclusion

Intestinal flora balance therapy based on probiotic support can effectively improve cognitive function, instantaneous memory, and ability of daily life in patients with Alzheimer's disease. However, more studies and long-term follow-up studies with higher methodological quality are needed to further verify.

Domain-general conflict monitoring predicts neural and behavioral indices of linguistic error processing during reading comprehension

The ability to detect and respond to linguistic errors is critical for successful reading comprehension, but these skills can vary considerably across readers. In the current study, healthy adults (age 18-35) read short discourse scenarios for comprehension while monitoring for the presence of semantic anomalies. Using a factor analytic approach, we examined if performance in nonlinguistic conflict monitoring tasks (Stroop, AX-CPT) would predict individual differences in neural and behavioral measures of linguistic error processing. Consistent with this hypothesis, domain-general conflict monitoring predicted both readers' end-of-trial acceptability judgments and the amplitude of a late neural response (the P600) evoked by linguistic anomalies. The influence on the P600 was nonlinear, suggesting that online neural responses to linguistic errors are influenced by both the effectiveness and efficiency of domain-general conflict monitoring. These relationships were also highly specific and remained after controlling for variability in working memory capacity and verbal knowledge. Finally, we found that domain-general conflict monitoring also predicted individual variability in measures of reading comprehension, and that this relationship was partially mediated by behavioral measures of linguistic error detection. These findings inform our understanding of the role of domain-general executive functions in reading comprehension, with potential implications for the diagnosis and treatment of language impairments. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Older bilinguals reverse language dominance less than younger bilinguals: Evidence for the inhibitory deficit hypothesis

Inhibitory control is thought to play a key role in how bilinguals switch languages and may decline in aging. We tested these hypotheses by examining age group differences in the reversed language dominance effect-a signature of inhibition of the dominant language that leads bilinguals to name pictures more slowly in the dominant than the nondominant language in mixed-language testing blocks. Twenty-five older and 48 younger Spanish-English bilinguals completed a cued language-switching task. To test if inhibition is applied at the whole-language or lexical level, we first presented one set of pictures repeatedly, then introduced a second list halfway through the experiment. Younger bilinguals exhibited significantly greater reversed language dominance effects than older bilinguals (who exhibited nonsignificant language dominance effects). In younger bilinguals, dominance reversal transferred to, and was even larger in, the second list (compared to the first). The latter result may suggest that inhibition is partially offset by repetition in ways that are not yet fully understood. More generally, these results support the hypotheses that aging impairs inhibitory control of the dominant language, which young bilinguals rely on to switch languages. Additionally, inhibition is applied primarily at the whole-language level, and speculatively, this form of language control may be analogous to nonlinguistic proactive control. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Failure to stop autocorrect errors in reading aloud increases in aging especially with a positive biomarker for Alzheimer's disease

The present study examined the effects of aging and CSF biomarkers of Alzheimer's disease (AD) on the ability to control production of unexpected words in connected speech elicited by reading aloud. Fifty-two cognitively healthy participants aged 66-86 read aloud 6 paragraphs with 10 malapropisms including 5 on content words (e.g., "window cartons" that elicited autocorrect errors to "window curtains") and 5 on function words (e.g., "thus concept" that elicited autocorrections to "this concept") and completed a battery of neuropsychological tests including a standardized Stroop task. Reading aloud elicited more autocorrect errors on function than content words, but these were equally correlated with age and Aβ1-42 levels. The ability to stop autocorrect errors declined in aging and with lower (more AD-like) levels of Aβ1-42, and multiplicatively so, such that autocorrect errors were highest in the oldest-old with the lowest Aβ1-42 levels. Critically, aging effects were significant even when controlling statistically for Aβ1-42. Finally, both autocorrect and Stroop errors were correlated with Aβ1-42, but only autocorrect errors captured unique variance in predicting Aβ1-42 levels. Reading aloud requires simultaneous planning and monitoring of upcoming speech. These results suggest that healthy aging leads to decline in the ability to intermittently monitor for and detect conflict during speech planning and that subtle cognitive changes in preclinical AD magnify this aging deficit. (PsycInfo Database Record (c) 2020 APA, all rights reserved).