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.
10 September 2018 in Neuropsychological Rehabilitation
This study investigated whether a treatment programme for spoken word retrieval, supplemented with written naming, was beneficial for an individual with right-hemisphere dominant semantic variant of PPA (svPPA). Assessment and treatment were delivered remotely through Skype. Treatment consisted of two phases of lexical retrieval therapy (Repetition and Reading in the Presence of a Picture: RRIPP), with and without written responses (Phases 1 and 2 respectively), and a third treatment phase based on the procedures of Conceptual Enrichment (COEN) therapy. The first two phases of treatment resulted in short-lasting improvements in spoken and written word retrieval, with greater improvement in Phase 2 when written production was also required. Both treatment phases resulted in gains only for treated items, but generalised to different depictions to those treated. However, Phase 2 also resulted in significant improvement of treated items on a comprehension task. COEN treatment did not result in significant gains in word retrieval or comprehension. This study reinforces the value of a simple lexical retrieval treatment delivered remotely. It adds to the current evidence that anomia in svPPA can be responsive to treatment, but also shows that challenges remain regarding maintenance effects and the generalisation of treatment effects to connected speech.
2 January 2015 in Australian Journal of Learning Difficulties
The main aim of this study was to develop standardised tests that assess some of the most important spelling skills for children in primary school: sound-letter mappings (non-lexical spelling) and word spelling accuracy (lexical spelling). We present normative comparison data for children in Grades 1–7 as well as measures of validity and reliability for both tests. Another aim of this study was to assess the relative prevalence of spelling difficulties that only affect one skill selectively (only lexical or only non-lexical spelling) or both. We found that throughout Grades 1–7, children were as likely to have selective as they were to have mixed difficulties. This underscores the importance of measuring lexical and non-lexical skills separately. The tests presented in this paper provide teachers and clinicians with the necessary tools to do exactly that.
18 November 2014 in Neuropsychological Rehabilitation
This paper provides a comprehensive review of treatment studies of acquired dysgraphia and the occurrence of generalisation after this treatment. The aim is to examine what determines the occurrence of generalisation by investigating the link between the level of impairment, the method of treatment, and the outcome of therapy. We present the outcomes of treatment with regard to generalisation in 40 treatment studies. We derive general principles of generalisation which provide us with a better understanding of the mechanism of generalisation: (1) Direct treatment effects on representations or processes; (2) interactive processing and summation of activation; and (3) strategies and compensatory skills. We discuss the implications of these findings for our understanding of the cognitive processes used for spelling. Finally, we provide suggestions for the direction of further research into this important area, as a better understanding of the mechanism of generalisation could maximise treatment effects for an individual with acquired dysgraphia.
Background: Studies on the nature of processing within the spelling system have provided evidence for interactivity, where activation between levels of processing flows bidirectionally. In particular, activated letters at the level of the graphemic buffer feed activation back to the lexicon. As a consequence lexical neighbours are activated, which in turn reactivate the graphemic buffer, supporting target selection and leading to an effect of orthographic neighbourhood size in spelling. As a consequence of this feedback, treating words with many neighbours may be more beneficial, and generalisation may be more likely to occur. Aims: The current study aimed to further examine this interactivity, and in particular the role of orthographic neighbourhood size in both treatment effects and generalisation, in the treatment of two individuals with acquired dysgraphia. Two phases of copy and recall treatment were conducted to investigate if orthographic neighbourhood size modulates treatment effects: in the first phase, treated words had no orthographic neighbours, in the second phase, treated words had many neighbours. Untreated control sets were used to investigate the influence of neighbourhood size on potential generalisation across items. Main Contribution: Results showed that treated items improved, however neighbourhood size did not significantly influence the size of the treatment effect for either participant, and no clear evidence was found for generalisation to untreated items. Conclusions: It is argued that (1) the amount of feedback from the buffer to the lexicon was reduced in the participants in this study, and consequently the treated items provide insufficient activation to orthographic neighbours or (2) the effect of feedback from neighbours is small compared to effects of treatment, resulting in similar results for treated words with and without neighbours. This study informs the relationship between spelling impairment and effects of treatment. Furthermore, the absence of generalisation emphasises the importance of choosing functionally relevant items for treatment.
This study investigated the nature of graphemic buffer functioning and impairment, through analysis of the spelling impairment shown by GEC, a man with acquired dysgraphia and clear characteristics of graphemic buffer impairment. We discuss GEC’s error patterns in relation to different processes of orthographic working memory. This is the first study to show the contribution of these processes in one individual through performance on different spelling tasks. GEC’s spelling errors in writing to dictation showed a linear serial position effect, including deletions of final letters. These “fragment errors” can be explained as the result of information rapidly decaying from the buffer (reduced temporal stability). However, in tasks that reduced working memory demands, GEC showed a different error distribution that may indicate impairment to a different buffer process (reduced representational distinctiveness). We argue that different error patterns can be a reflection of subcomponents of orthographic working memory that can be impaired separately.