Developmental trajectories of metacognitive processing and executive function from childhood to older age.

The modern understanding of the term metacognition encompasses two levels of processing: a lower level awareness or knowledge of one's own thoughts and a higher level regulation or control of our thinking. Metacognition, therefore, bears conceptual similarity with executive function: both are concerned with top-down monitoring and control of cognition in the service of ongoing goal-directed behaviour. Previous studies have shown a possible executive function advantage in multilingual speakers but also a possible disadvantage in metacognitive processing. To progress theory on metacognitive processing and the relationship with executive function and linguistic experience across the lifespan, we conducted a study testing 330 healthy individuals in four age groups from 7 to 80 years old. All participants performed a metacognition task and two measures of executive function, which included the Simon task and the Tower of London task. Half the participants were multilingual speakers since birth. We built developmental trajectories of metacognitive and executive function across the lifespan. The best metacognitive efficiency was observed in mid-adulthood, whereas the best executive function processing reached its peak in young adulthood. A steep cognitive decline was observed in older age, while metacognitive efficiency was preserved. Exploratory factor analysis indicated that metacognition and executive function are served by different factors across all ages. Contrary to previous findings in the bilingual literature, a multilinguistic experience conferred neither any significant advantage nor disadvantage in both executive function and metacognitive processing across the lifespan.

A role for the cerebellum in the control of verbal interference: Comparison of bilingual and monolingual adults.

We evaluate brain structure sensitivity to verbal interference in a sentence interpretation task, building on previously reported evidence that those with better control of verbal interference show higher grey matter density in the posterior paravermis of the right cerebellum. We compare brain structure sensitivity to verbal interference control across two groups, English monolingual (N = 41) and multilingual (N = 46) adults. Using voxel-based morphometry, our primary goal was to identify and explore differences in regional patterns of grey matter sensitivity to performance on the sentence interpretation task, controlling for group variability in age, nonverbal reasoning and vocabulary knowledge. There was no group difference in performance but there was a significant group effect in grey matter sensitivity to task performance in our region of interest: stronger sensitivity in the paravermis in bilinguals compared to monolinguals in accuracy performance in the high (relative to low) verbal interference condition. This effect was observed when the linguistic interference was presented in an unfamiliar language (Greek) but not when presented in the familiar language (English). Our findings suggest that multilanguage acquisition mediates regional involvement within the language network, conferring enhanced functional plasticity within structures (including the paravermis) in the service of control of linguistic interference.

Developmental trajectories of control of verbal and non-verbal interference in speech comprehension in monolingual and multilingual children.

Research on speech comprehension in noise indicates that a multilinguistic experience may confer advantages in filtering out verbal interference, an effect observed both in children acquiring two or more languages since birth (Filippi, Morris, Richardson, et al., 2015) and in second language learner adults (Filippi, Leech, Thomas, et al., 2012). A possible interpretation for this advantage is that the multilingual mind is "trained" to control interference from the language not in use. This constant effort may support optimization of cognitive resources that are necessary for successfully selecting, processing and interpreting complex linguistic information. The present study aimed to extend this line of research by including a non-verbal interference condition. 209 typically developing children (132 English monolinguals and 77 multilinguals from different linguistic backgrounds) carried out a sentence interpretation task in the presence of verbal and non-verbal interference. We found no evidence for a reliable group difference in our data. Instead, findings indicated that background cognitive ability and socioeconomic status were the best indicators of successful control of interference, irrespective of whether participants were bilingual or monolingual. These findings are discussed in the light of previous research and, more widely, on the account of the current debate on the bilingual advantage.

Evidence against a cognitive advantage in the older bilingual population.

Recent evidence has challenged long-standing claims that multi-language acquisition confers long-term advantages in executive function and may protect against age-related cognitive deterioration. We assessed evidence for a bilingual advantage in older monolingual and bilingual residents matched on age, gender, and socioeconomic status. A comprehensive battery of tests was administered to measure non-verbal reasoning, working memory capacity, visuo-spatial memory, response inhibition, problem solving, and language proficiency. Analyses, including Bayes factors, revealed comparable performance in both groups, with no significant differences on any task (and the only trend, found for the Tower of London task performance, indicated a monolingual advantage). Overall, therefore, our findings run counter to the bilingual advantage hypothesis. We consider the implications of our study and offer suggestions for future work in this area.

The Importance of Socioeconomic Status as a Modulator of the Bilingual Advantage in Cognitive Ability.

Between-group variability in socioeconomic status (SES) has been identified as a potentially important contributory factor in studies reporting cognitive advantages in bilinguals over monolinguals (the so called "bilingual advantage"). The present study addresses the potential importance of this alternative explanatory variable in a study of low and high SES bilingual and monolingual performance on the Simon task and the Tower of London (TOL) task. Results indicated an overall bilingual response time advantage on the Simon task, despite equivalent error rates. Socioeconomic status was an important modulator in this effect, with evidence that bilingualism may be particularly important in promoting speed of processing advantages in low status individuals but have little impact in high status individuals. However, there was a monolingual advantage on the TOL test of executive planning ability. Together, our findings run counter to the central assertion of the bilingual advantage account, that the process of multi-language acquisition confers a broad cognitive advantage in executive function. We discuss these findings in the context of SES as an important modulator in published studies advocating a bilingual cognitive advantage.

Mortality Risk in Alcoholic Patients in Northern Italy: Comorbidity and Treatment Retention Effects in a 30-Year Follow-Up Study.

AIMS: To analyse the general and cause-specific mortality over the course of 30 years among subjects treated for alcohol use disorders (AUD) in Northern Italy. METHODS: Cohort of 2499 subjects followed-up for mortality until 31 December 2012. Standardized mortality ratios (SMRs) and 95% confidence intervals (CI) were computed to compare the mortality in the cohort with the general population. Cox regression was used to study the effect of psychiatric disorders, burden of physical comorbidity and retention in treatment on mortality, controlling for socio-demographic factors. RESULTS: During the follow-up, 435 deaths occurred. Compared with the general population, alcoholics experienced a 5-fold increased mortality (SMR: 5.53; 95% CI: 5.03, 6.07). Significant excess mortality was observed for a range of specific causes: infections, cancers, cardiovascular, respiratory and digestive system diseases as well as violent causes. In multivariate analysis, the hazard of dying was lower for female gender (hazard ratio [HR]: 0.62; 95% CI: 0.46, 0.84) and for increasing length of retention in treatment (HR for third tertile vs first tertile: 0.43; 95% CI: 0.32, 0.57). Burden of physical comorbidity was associated with increased hazard of dying (HR for 3+ comorbidities vs no comorbidities: 4.40; 95% CI: 2.91, 6.66). Psychiatric comorbidity was not associated with mortality. CONCLUSIONS: Despite the harmful effect of AUD, retention in treatment represented a protective factor against death, suggesting that strategies supporting primary medical- and social-care may effectively reduce premature mortality.