The aim of the study is to explore the differential effects of neurodegenerative disorders on cross-language interference and facilitation, by comparing the performance in a bilingual Stroop task of Catalan–Spanish bilinguals with different neurodegenerative disorders [Mild Cognitive Impairment (MCI), n = 16; Alzheimer's disease (AD), n = 16; and Parkinson's disease (PD), n = 16)] and healthy controls (n = 14). Interference is the difference in naming latencies between the incongruent (colour words not matching with their ink colour) and control (non-colour words) conditions. Facilitation is the difference between the control and congruent conditions (colour words matching with their ink colour).

The results showed that AD and MCI patients, but not PD, showed a larger interference effect than healthy controls. Nevertheless, the patient groups showed the same facilitation effect as healthy controls.

The contribution of cortical and subcortical brain areas to cross-language interference suppression is discussed in relation to the type of brain degeneration.

BAbSANT (Bilingual Abstract Semantic Associative Network Training) is a novel, theoretically motivated approach to anomia therapy for bilingual persons with aphasia (BPWA). We report on a Russian-dominant, Russian–English BPWA, who was trained on abstract English and Russian words. We hypothesized both within- and cross-language generalization when the non-dominant language was trained, and only within-language generalization when the dominant language was trained. We also hypothesized that cross-language generalization is modulated by nonverbal cognitive control. Results revealed that when English abstract words were trained, within-language generalization to concrete words and cross-language generalization to Russian abstract words was observed, confirming our first hypothesis. However, our second hypothesis was not confirmed. When Russian was trained, direct effects of treatment and within- or cross-language generalization effects were not observed. Our third hypothesis was confirmed. Results from cognitive control tasks from this individual suggest a role of nonverbal cognitive control on cross-language treatment outcomes.

Semantic feature-based treatments (SFTs) are effective rehabilitation strategies for word retrieval deficits in bilinguals with aphasia (BWA). However, few studies have prospectively evaluated the effects of key parameters of these interventions on treatment outcomes. This study examined the influence of intervention-level (i.e., treatment language and treatment sessions), individual-level (baseline naming severity and age), and stimulus-level (i.e., lexical frequency, phonological length, and phonological neighborhood density) factors on naming improvement in a treated and untreated language for 34 Spanish–English BWA who completed 40 hours of SFT. Results revealed significant improvement over time in both languages. In the treated language, individuals who received therapy in their L1 improved more. Additionally, higher pre-treatment naming scores predicted greater response to treatment. Finally, a frequency effect on baseline naming accuracy and phonological effects on accuracy over time were associated with differential treatment gains. These findings indicate that multilevel factors are influential predictors of bilingual treatment outcomes.

Bilingualism has been shown to contribute to increased resilience against cognitive aging. One of the key brain structures linked to memory and dementia symptom onset, the hippocampus, has been observed to adapt in response to bilingual experience – at least in healthy individuals. However, in the context of neurodegenerative pathology, it is yet unclear what role previous bilingual experience might have in terms of sustaining integrity of this structure or related behavioral correlates. The present study adds to the limited cohort of research on the effects of bilingualism on neurocognitive outcomes in Mild Cognitive Impairment (MCI) using structural brain data. We investigate whether bilingual language experience (operationalized as language entropy) results in graded neurocognitive adaptations within a cohort of bilinguals diagnosed with MCI. Results reveal a non-linear effect of bilingual language entropy on hippocampal volume, although they do not predict episodic memory performance, nor age of MCI diagnosis.

Bilingualism is thought to confer advantages in executive functioning, thereby contributing to cognitive reserve and a later age of dementia symptom onset. While the relation between bilingualism and age of onset has been explored in Alzheimer's dementia, there are few studies examining bilingualism as a contributor to cognitive reserve in frontotemporal dementia (FTD). In line with previous findings, we hypothesized that bilinguals with behavioral variant FTD would be older at symptom onset compared to monolinguals, but that no such effect would be found in patients with nonfluent/agrammatic variant primary progressive aphasia (PPA) or semantic variant PPA. Contrary to our hypothesis, we found no significant difference in age at symptom onset between monolingual and bilingual speakers within any of the FTD variants, and there were no notable differences on neuropsychological measures. Overall, our results do not support a protective effect of bilingualism in patients with FTD-spectrum disease in a U.S. based cohort.

The umbrella term cognitive reserve-enhancing factors refers to those experiential and lifestyle factors (such as intellectual activities, regular physical exercise, healthy nutrition, educational attainment, etc.) that may help individuals to compensate for age-related neural deterioration, thus enabling them to maintain relatively stable cognitive functioning during senescence. In the last 10 years, mounting evidence has shown that speaking a second language is a powerful cognitive reserve contributor, which could mitigate the consequences of healthy aging and contribute to the delay of dementia onset. In this piece, we argue that bilingualism may play a unique role among the well-known cognitive reserve-enhancing factors, thus contributing to the achievement of successful aging in a distinctive fashion. After reviewing behavioral and neuroimaging evidence for bilingualism-induced protection against healthy and pathological cognitive aging, we discuss theoretical reasons and experimental findings supporting the view that bilingualism should be granted an individual spot among reserve-enhancing life experiences.