The decline of cognitive skills throughout healthy or pathological aging can be slowed down by experiences which foster cognitive reserve (CR). Recently, some studies on Alzheimer's disease have suggested that CR may be enhanced by life-long bilingualism. However, the evidence is inconsistent and largely based on retrospective approaches featuring several methodological weaknesses. Some studies demonstrated at least 4 years of delay in dementia symptoms, while others did not find such an effect. Moreover, various methodological aspects vary from study to study. The present paper addresses contradictory findings, identifies possible lurking variables, and outlines methodological alternatives thereof. First, we characterize possible confounding factors that may have influenced extant results. Our focus is on the criteria to establish bilingualism, differences in sample design, the instruments used to examine cognitive skills, and the role of variables known to modulate life-long cognition. Second, we propose that these limitations could be largely circumvented through experimental approaches. Proficiency in the non-native language can be successfully assessed by combining subjective and objective measures; confounding variables which have been distinctively associated with certain bilingual groups (e.g., alcoholism, sleep disorders) can be targeted through relevant instruments; and cognitive status might be better tapped via robust cognitive screenings and executive batteries. Moreover, future research should incorporate tasks yielding predictable patterns of contrastive performance between bilinguals and monolinguals. Crucially, these include instruments which reveal bilingual disadvantages in vocabulary, null effects in working memory, and advantages in inhibitory control and other executive functions. Finally, paradigms tapping proactive interference (which assess the disruptive effect of long-term memory on newly learned information) could also offer useful data, since this phenomenon seems to be better managed by bilinguals and it becomes conspicuous in early stages of dementia. Such considerations may shed light not just on the relationship between bilingualism and CR, but also on more general mechanisms of cognitive compensation.

No abstract

The processes tapped by the widely-used word association (WA) paradigm remain a matter of debate: while some authors consider them as driven by lexical co-occurrences, others emphasize the role of meaning-based connections. To test these contrastive hypotheses, we analyzed responses in a WA task in terms of their normative defining features (those describing the object denoted by the cue word). Results indicate that 72.5% of the responses had medium-to-high coincidence with such defining semantic features. Moreover, 75.51% of responses had medium-to-high values of Relevance (a measure of the importance of the feature for construing a given concept). Furthermore, most responses (62.7%) referred to elements of the situation in which the concept usually appears, followed by sensory properties (e.g., color) of the denoted object (27.86%). These results suggest that the processes behind WA tasks involve a reactivation of the cue item's semantic properties, particularly those most relevant to its core meaning.

The effects of long-term treatment in a demented patient were evaluated in this study. One individual diagnosed with Alzheimer's dementia (AD) was treated with neuropsychological rehabilitation techniques as well as drugs for a period of 2 years and 10 months. An A-B-A-B design was performed for the cognitive treatment. Neuropsychological treatment consisted of a combination of direct re-training and training in activities of daily living. Cognitive performance was monitored with the Mattis Dementia Rating Scale. Results showed improvement and a slower decline during the treatment phases (A) as compared to the no-treatment phases (B). The Conceptualisation and Attention subscales benefited most followed by the Memory subscale. Long-term treatment was shown to be effective in AD. Although cognitive drugs may have been beneficial neuropsychological rehabilitation played an important role in the success of this treatment, appearing as a necessary condition.