RESUMEN
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.
RESUMEN
Recently, doubts were raised about the existence of the bilingual advantage in cognitive control. The aim of the present review was to investigate the bilingual advantage and its modulating factors. We searched the Medline, ScienceDirect, Scopus, and ERIC databases for all original data and reviewed studies on bilingualism and cognitive control, with a cut-off date of 31 October 2018, thereby following the guidelines of the preferred reporting items for systematic reviews and meta-analysis (PRISMA) protocol. The results of the 46 original studies show that indeed, the majority, 54.3%, reported beneficial effects of bilingualism on cognitive control tasks; however, 28.3% found mixed results and 17.4% found evidence against its existence. Methodological differences seem to explain these mixed results: Particularly, the varying selection of the bilingual participants, the use of nonstandardized tests, and the fact that individual differences were often neglected and that longitudinal designs were rare. Therefore, a serious risk for bias exists in both directions (i.e., in favor of and against the bilingual advantage). To conclude, we found some evidence for a bilingual advantage in cognitive control; however, if significant progress is to be made, better study designs, bigger data, and more longitudinal studies are needed.
RESUMEN
Background: Pharmacological treatment is still the key intervention in the disease management of long-term patients with schizophrenia; however, how it affects sleep and whether gender differences exist remains unclear. Methods: Forty-six long-term outpatients with schizophrenia entered the study. The numbers of antipsychotics, sleep medications, antidepressants, and anxiolytics were analyzed. Moreover, all patients were tested using the Pittsburgh Sleep Quality Index (PSQI) and the Epworth Sleepiness Scale (ESS). Correlation analyses were conducted between the medication used and the scores on the two subjective sleep inventories. Results: A large variability, ranging from 0 to 8, in the total number of psychiatric drugs per person was found between the patients. Despite ongoing pharmacological treatment, the patients scored high on the PSQI, but not on the ESS; this indicates that they report problems with sleep, but not with daytime sleepiness. A significant positive correlation between the use of antipsychotics and the ESS score, but not the PSQI score, was found; moreover, no gender differences were found. Conclusions: A large variability exists in the pharmacological treatment of long-term patients with schizophrenia. To date, patients' sleep problems have been insufficiently treated, and gender differences have not been adequately accounted for in the pharmacological treatment of schizophrenia. More and larger international clinical studies are warranted to verify the findings of the present preliminary pilot study before any firm conclusions can be drawn and before any changes to the drug treatment of male and female patients with schizophrenia can be recommended.